Water Supplies Department
Water Authority issues guidelines including Hong Kong Waterworks Standard Requirements for Plumbing Installation in Buildings and Water Supplies Department Circular Letters to Licensed Plumbers and Authorized Persons to set out the normal requirements, practices and procedures for the construction, installation, alteration or removal of inside service and fire service.
With an aim to providing more comprehensive information in a user-friendly manner to the practitioners, this Handbook on Plumbing Installation for Buildings summarises the current normal requirements that the practitioners are expected to observe as set out in the Waterworks Ordinance (Cap 102), the Waterworks Regulations (Cap 102 A), the Hong Kong Waterworks Standard Requirements for Plumbing Installation in Buildings and Water Supplies Department Circular Letters issued to Licensed Plumbers and Authorized Persons.
In all circumstances, it is the responsibility of the applicants, Authorised Persons and Licensed Plumbers to ensure that the applications comply with the statutory requirements and the requirements of the Water Authority. This book is compiled by the Water Supplies Department to serve as a handy reference only. It is therefore important for the applicants, Authorised Persons and Licensed Plumbers to refer to the original publications and to make reference to the latest information on new or modified requirements issued by the Water Authority and relevant British Standards before they submit their applications. In case there is any discrepancy between the original publications and this book, the original publications should take precedence.
The definitions used in this booklet are as follows:
A person who is approved under Section 7 of Waterworks Ordinance as an agent of a communal service.
An Authorized Person registered under the Buildings Ordinance.
That part of a fire service or inside service which is used in common by more than one consumer in the same premises.
Connexion to the Main
The pipe between the main and the control valve which is nearest to the main and which regulates the flow of a supply from the main into a fire service or inside service, such control valve and all fittings between such control valve and the main.
A person who is approved under Section 7 of Waterworks Ordinance as a consumer of a fire service or inside service.
Direct Supply System
A plumbing system which conveys water directly from the government water mains to the point of usage without any transit water storage tanks.
The pipes and fittings in premises, and any pipes and fittings between the premises and a connexion to the main, which are used or are intended to be used for a supply solely for the purposes of fire fighting.
Any apparatus, cistern, cock, equipment, machinery, material, tank, tap and valve; and any appliance or device other than a meter, which is installed or used in a fire service or inside service.
Indirect Supply System
A plumbing system which conveys water from the government water mains to the point of usage through a transit water storage tank.
The pipes and fittings in premises, and any pipes and fittings between the premises and a connexion to the main (other than the pipes and fittings forming part of a fire service) which are used or are intended to be used for the purposes of a supply.
A person licensed under the Waterworks Ordinance to construct, install, maintain, alter, repair or remove fire services or inside services.
Main includes a connexion to the main and any pipe owned by the Government and maintained by the Water Authority for the purposes of a supply.
An appliance or device owned by the Government and maintained by the Water Authority for the purpose of measuring water consumption.
Any building or structure or any part thereof and any place in which there is a fire service, inside service or any part of the waterwork; or in which a fire service or inside service is intended to be constructed or installed.
The Director of Water Supplies
Any property occupied, used or maintained by the Water Authority for the purpose of water supply, including all water gathering grounds.
Commonly Used Waterworks Fittings
The functions of some commonly used waterworks fittings are described below:
a valve in a water service that opens to admit air if the pressure within the water service falls below atmospheric pressure.
a valve that controls the entry of water into a storage cistern or flushing cistern, closing off the supply when the water level in the cistern has reached a predetermined level. It is sometimes called a ball cock or float-operated valve.
an enclosed vessel in which water is heated by the direct application of heat
a valve in which a disc is rotated about a diametric axis of a cylinder to vary the aperture. It is used where space is limited or more sophisticated control is required.
a storage vessel, not open to the atmosphere, in which a supply of water is heated. The vessel contains an element, such as a coil of pipe, through which is passed a supply of hot water or steam, in such a way that the two supplies do not mix, heat being transferred through the walls of the element.
a closed vessel for accommodating the thermal expansion of water in a pressurized hot water heating system
a device incorporating a float that operates a switch in response to changes in the level of a liquid.
a valve that provides a straight-through passage for the flow of fluid and in which the passage can be closed by a gate. It is used where the water pressure is low and on distribution pipework from a storage cistern. This valve is sometimes referred to as a fullway gate valve because when it is fully open, there is no restriction of flow through the valve.
Loose Jumper Type Stopcock
a screwdown pattern valve with horizontal inlet and outlet connections. It incorporates a loose jumper valve permitting flow in one direction only. It is used for isolating the supply of water in a high pressure pipeline. In case the supply main is shut off and drained down for any reason, the ‘non-return’ action of the loose valve plate will stop any backflow from the service pipe.
a valve that prevents reversal of flow in the pipe of a water supply by means of the check mechanism, the valve being opened by the flow of water and closed by the action of the check mechanism when the flow ceases, or by back pressure. It is also known as check valve.
Pressure Reducing Valve
a valve that reduces the pressure of a fluid immediately downstream of its position in a pipeline to a preselected value or by a predetermined ratio.
Responsibilities of Water Authority and Consumers/Agents
Divisions of Responsibilities
The division of responsibilities for Water Authority, consumer/agent on the maintenance of water supply systems are as follows
Obligations of Consumers/Agents
The obligations of a consumer/agent under the Waterworks Ordinance are as follows:
The liability of a consumer/agent in respect of a supply will continue, until another consumer/agent is approved by the Water Authority in his/her place or an undertaking given under Section 7 of Waterworks Ordinance is cancelled by the Water Authority.
General Principles for Installing Plumbing Works
The general principles for installing plumbing works are as follows:
- all pipes and fittings shall comply with the requirements of Waterworks Ordinance, Cap. 102 and Waterworks Regulations, Cap. 102A; and
- all plumbing works, except those works of a minor nature, shall be carried out by a licensed plumber.
As far as practicable, it is advised that the communal service should not be run through the individual premises because access to the communal service for routine inspection, maintenance and repair of the communal service may be restricted and obstructed by individual premises.
Application for New Water Supply
Plumbing installation that receives water supply from the Waterworks has to comply with the Waterworks requirements under the provision of the Waterworks Ordinance/Regulations, Hong Kong Waterworks Standard Requirements for Plumbing Installation in Buildings (HKWSR), and Water Supplies Department Circular Letters issued to Licensed Plumbers and Authorized Persons. Approval from the Water Authority is required in order to construct, install, alter or remove a plumbing installation.
Plumbing installation that is not to receive water supply from the Waterworks does not need the approval of the Water Authority. However, it is advisable for the plumbing installation to follow the Waterworks requirements such that when a supply from the Waterworks becomes necessary, the modification of the plumbing installation to comply with the Waterworks requirements will be minimized.
Minimum Residual Pressure
The Water Authority maintained a minimum residual pressure of 30-metre head in most existing fresh water supply zones except at their extremities. To tie in with various national standards and international practice, the Water Authority has decided to lower the minimum residual pressure to 20-metre head, except at the extremities of supply zones for new developments in new or existing supply zones or re-developments in existing supply zones, for plumbing proposals first submitted to the Water Authority on or after 1 April 2008.
Application for Water Supply for two- storey Warehouse through One Stop Centre (OSC)
Applicant may apply for water supply for 2-storey warehouse through the OSC operated under the Efficiency Unit (EU) of Chief Secretary for Administration’s Office with effect from 1 December 2008. The OSC is an option in addition to the existing channels of application. It aims to streamline the application process by setting a centralized office for receiving submissions of building plans and related applications (including technical audit for water supply connection works) and coordinating joint inspections for two-storey warehouses.
Household-Scale Solar Water Heater System for Village House
The Electrical and Mechanical Services Department (EMSD) provides general guidelines for the intending purchasers, owners and installers of household-scale solar water heating system to be installed at village houses. The guidelines help the above people to understand the installation requirements and application procedures associated with the installation, operation and maintenance of the aforesaid solar water heating system.
The applicant should obtain from the Water Authority such information as are relevant to the design of the plumbing installation and submit the plumbing proposal to the Water Authority for approval. The Water Authority will as far as practical provide the information to the applicant such as location and size of connection points, water pressures, single or double-end fed supply.
WSD pledges to vet submissions of plumbing proposals for new building developments in 20 working days. Sometimes it may take a longer time for the applicant to clarify on points not clearly mentioned in the proposal. Therefore, it is advisable for the applicant to submit the plumbing proposal to the Water Authority for approval early in order not to delay the plumbing works. No plumbing work shall commence before the plumbing proposal has been approved by the Water Authority. It is important for the applicant to bear in mind the need to accommodate all the inside service and fire service, which include water storage tanks, break pressure tanks, meter rooms etc. together with the associated access, in the layout and structural design of the development.
Prior to carrying out replumbing works within private buildings, approval from the Water Authority must be sought. Failing this is in contravention of Section 14 of the Waterworks Ordinance and the offenders are liable to prosecution.
The Water Authority would like to replace the old meters of the buildings in conjunction with the replumbing works. For better co-ordination of work, it is considered more appropriate to have the meter replacement works to be carried out by the same licensed plumber engaged in the replumbing works. In our approval to the application for replumbing works, the licensed plumber will be invited to carry out the meter replacement works and our District staff will inform the licensed plumber of the detailed arrangement.
Applicants should submit Application Form WWO 542 together with plumbing proposals as listed in Appendix A3.
One set of the plumbing proposals is required. All drawings shall be:
identified by drawing numbers and drawing titles;
folded to a plan size not exceeding the A4 size (i.e. 297 mm by 210 mm) and in such a way to display the drawing numbers and drawing titles.
For revised drawings, details of all the amendments shall be listed as notes to the drawings and the amendments shall also be highlighted or coloured in the drawings for easy identification. The submission, whether approved or not, will not be returned to the applicant. Once approved, no details in the submission shall be altered without the written approval of the Water Authority.
Application for New Water Supply - Response Time
The Water Authority has provided target response time for completing the key activities in respect of the application for new water supply in WSD Circular Letter No. 3/2010. The Water Authority from time to time reviews the target response time to look for improvements.
In case an application is not processed within the target response time or the applicant wants to discuss the way in which an application has been handled, the applicant can contact the responsible staff of WSD’s Regional Office to which the application has been submitted. The list of case officers and business facilitation officers can be obtained from webpage
Excavation Permit Fee Under the Land Ordinance (Miscellaneous Provision)
According to Chapter 28 Land (Miscellaneous Provisions) Ordinance, any person who wishes to make any excavation in unleased land must apply for an excavation permit. Under the Ordinance, a fee is required for the excavation permit. To recover the cost, the Water Authority will issue an additional and separate demand note on the estimated excavation permit fees to applicants. This demand note is subject to adjustment according to the actual final excavation permit fees incurred for the work.
Commencement of Work
The licensed plumber, who is employed by the applicant, should submit Parts I, II & Annex to the Form WWO 46 - “Application for Constructing, Installing, Altering or Removing an Inside or Fire Service” to the Water Authority for approval before commencement of plumbing works. Part I shall also be signed by the Authorized Person for new building project. On completion of the processing, the licensed plumber will receive Part III of Form WWO 46 with a form serial number printed on it. A copy of Parts I and II of Form WWO 46 will also be returned to the licensed plumber.
The licensed plumber and the Authorized Person (if applicable) shall certify that the pipes and fittings to be installed and any materials to be used for the construction, installation, alteration or removal (construction etc.) of the Approved Plumbing Works covered by the submitted Form WWO 46, including those as listed on the attached Annex and those not listed, shall be as prescribed by the Waterworks Regulations, Cap. 102A.
Before commencement of plumbing works, when signing Form WWO 46, the licensed plumber should take all necessary steps to ensure that the pipes and fittings to be installed and any materials to be used shall be as prescribed by the Waterworks Regulations. Similarly, when the Authorized Person (if applicable) signs the Form WWO46 and Form WWO 132, he / she shall ensure that there is an effective internal checking system to help him / her certify that the pipes and fittings installed or to be installed and any materials used or to be used are in full compliance with the relevant provisions in the Waterworks Regulations.
Form WWO 46 Submission Practice
WWO46 (excluding explanatory notes) can be mailed or faxed to the Water
Authority. WWO46 form should be in A4 size.
WWO46 will be scanned into the EDMS. The original will be disposed of and will not be returned to the LP.
Staff of Water Authority will return a printout copy of WWO46 with Part III endorsed.
For reporting completion of whole or part of plumbing, LP needs to complete and sign Part IV before submission to the Water Authority.
If a schematic drawing is necessary to indicate the completion of a part of plumbing, the drawing should be of A4 size.
Whenever there is any minor alteration initiated by the LP, LP can mail or fax a copy of previous WWO 46 with his/her signature and date on each entry of such alteration(s). This needs to be done before staff of the Water Authority conducts inspection.
Staff of Water Authority will return a printout copy of WWO 46 with Part V endorsed on site if the plumbing is found generally in order.
If the plumbing is found not in order, staff of Water Authority will return a printout copy of WWO 46 with Part V signed for rejection and will attach a WWO 1008.
When LP has rectified the irregularities, LP needs to re-date WWO 46 and submit it to the Water Authority.
Interim Inspections and Final Inspections
After completion of plumbing works, the licensed plumber concerned is required to report completion to the Water Authority and requests the Water Authority to inspect the completed works via the submission of Form WWO46 Part IV. The inspection will be an interim inspection when the completed works are only part of the plumbing works such as underground pipeworks or an inside service or a fire service to be concealed. On the other hand, when the completed works are the whole of the plumbing works, the inspection conducted by the Water Authority will be a final inspection.
The interim inspection will be carried out on a random basis and applied a risk based approach. The inspection should be such that approximately 10% of the total plumbing works will be inspected except that for those underground pipeworks without a meter (not a master meter or check meter position), full inspection will be carried out. Upon receipt of Form WWO46 Part IV, the staff of Water Authority should arrange the interim / final inspection within 7 clear working days.
Completion of Work
After completion of plumbing works, the licensed plumber should report completion of work on Part IV of Form WWO 46 and request the Water Authority to arrange for final inspection. Water supply will only be effected after the inside service / fire service has been checked in order and the necessary requirements such as satisfactory water sampling test results are fulfilled.
Given that WSD’s inspections shall include but not limited to carrying out spot-check of the pipes and fittings at the premises and random sampling of the water supply on the Approved Plumbing Works, attention of the licensed plumber is drawn to the licensed plumber’s duty to construct. etc of the Approved Plumbing Works covered by the submitted Form WWO 46 in compliance with the approved plumbing proposals and the Waterworks Regulations.
A licensed plumber can be assisted by workers in carrying out the works, but under no circumstances should a licensed plumber use his licence to enable non-licensed persons to undertake plumbing works without involving himself/herself in the supervision of the work.
Furthermore, neither the approval of the plumbing proposals nor the granting of the connection to the main and the installation of the part of the fire service or inside service on land held by the Government shall be construed as a ratification of any contravention of any of the provisions of the Waterworks Ordinance or the Waterworks Regulations.
Category of Grades
A licensed plumber (LP) is categorised into two grades
Awareness of Anti-corruption Laws
Licensed Plumber should always be aware of the anti-corruption laws and avoid to contravene them during their course of works.
Works of a Minor Nature
Pursuant to Section 14 of the Waterworks Ordinance (WWO), no person shall, unless with the permission in writing of the Water Authority, construct, install, alter, or remove a fire service or inside service. Besides, Section 15 of the WWO also stipulates that, no fire service or inside service shall be constructed, installed, maintained, altered, repaired or removed by a person other than a licensed plumber or a public officer authorized by the Water Authority.
The Water Authority (WA) may waive the requirement of permission under Section 14 of the WWO in the case of alterations to a fire service or inside service which are, in his opinion, of a minor nature. Moreover, under Section 15 of the WWO, alterations or repairs to a fire service or inside service which are, in the opinion of the WA, of a minor nature, may be carried out by a person other than a licensed plumber.
Examples of alterations or repairs to inside services or fire services satisfying the following 5 conditions are considered as works of a minor nature:
- do not change the purpose of supply (e.g. from domestic purpose to trade purpose) or the existing usage (e.g. from fire fighting to vehicle washing or internal cleansing in building, from irrigation to air-conditioning) of the plumbing installation already approved by the Water Authority (WA);
- do not change from the indirect supply of the plumbing installation already approved by the WA to direct supply;
- do not require dismantling and reinstallation of the water meter installed by the WA;
- do not involve soldering for connecting copper pipes; and
- do not require provision of backflow preventive devices for water using apparatus [other than washing machine, dish-washing machine or water filter (faucet or countertop type).
.“Domestic purpose” means a purpose connected solely with the occupation of a dwelling-house and does not include a purpose connected with a garden, lawn, playground or swimming pool appurtenant to a dwelling-house. “Trade purpose” means water supplied for use for any purpose connected with a trade, manufacture or business, other than a construction purpose, shipping purpose or domestic purpose.
.“Fitting” means any apparatus, cistern, cock, equipment, machinery, material, tank, tap, valve and any appliance or device other than a meter installed by the Water Authority, which is installed or used in a fire service or inside service.
Minor alterations and repairs to inside services or fire services shall conform to waterworks requirement in respect of quality of workmanship and material. It is in the interest of the consumer/agent that in case of doubt to notify the Water Authority of his intention, so that the Water Authority can give advice to the consumer/agent.
Renewal of Plumber’s Licences
For renewing plumber’s licences, licence holders may come, in person, to WSD Customer Enquiry Centres at Wan Chai or Mong Kok to renew their licence for a new term no earlier than three months before the expiry of the current licence. A licence holder has to bring
along his/her identity card, one recent photograph in size of 38 mm by 25 mm for payment of licence fee and collection of the new licence at any one of the following Customer Enquiry Centres: The payment of licence fee is prescribed in latest enactment of paragraph 6 in Part I, Schedule 1 of the WWR. The addresses and office hours of Customer Enquiry Centres are:
Metering is required to measure water consumed for billing purposes. Meter position shall be provided by the LP (employed by the applicant) for meter installation while water meters will be provided by the Water Authority. Water meters may be installed either by the Water Authority or the licensed plumber.
The size and location of the water meter will be determined by the Water Authority. For domestic supply, a meter size of 15mm is usually recommended. For trade and industrial supply, the meter size is determined based on the actual water consumption.
However, a check meter position and/or a waste detection chamber shall be provided at the inlet pipe to the communal service for consumption check and waste detection purposes. The check meter position and/or a waste detection chamber shall be close to the lot boundary or close to the point of connection from the internal distribution mains whichever is applicable.
Collection of Large Quantity of Water Meters (200 or more)
- At the time of notifying commencement of plumbing works using Parts I & II of Form WWO46, AP/LP is required to submit a meter acquisition programme giving the number and size of water meters and the time that the meters are expected to be available for installation.
- AP/LP will receive a reply letter. If the programme is not acceptable, it should be revised and re-submitted for consideration.
- AP/LP need to confirm the acquisition of each batch of water meters in writing at least three weeks before the proposed date of collection of the meters.
- AP/LP will then receive a reply letter (Form WWO465) giving the arrangement and contact staff for collection of the water meters. AP/LP will also receive an Undertaking (From WWO466) for completion and return when he collects the meters.
- AP/LP should make appointment with staff stipulated in Form WWO 465 to obtain “Collection Note” as well as the softcopy and/or hardcopy of the Meter Installation Table.
- AP/LP should bring along the “Collection Note” together with the duly completed Undertaking (Form WWO466) to the designated WSD Regional Stores to collect the water meters. AP/LP or his authorized representative is required to sign on the
Stock Issue Note with the company chop and hand in the duly completed Undertaking (From WWO466) at the time of collecting the meters.
- LP should return the softcopy and/or hardcopy of the completed Meter Installation Table to the Document Management Centre at 43/F Immigration Centre 7 Gloucester Road Wanchai Hong Kong when reporting completion of plumbing works using Part IV of Form WWO46.
Collection of Small Quantity of Water Meters (Less than 200)
- LP can proceed to make appointment with staff stipulated in approval letter to obtain “Collection Note” as well as the softcopy and/or hardcopy of the Meter Installation Table after receiving Part III of Form WWO46.
- AP/LP should bring along the “Collection Note” together with the duly completed Undertaking (Form WWO466) to the designated WSD Regional Stores to collect the water meters. AP/LP or his authorized representative is required to sign on the Stock Issue Note with the company chop and hand in the duly completed Undertaking (Form WWO466) at the time of collecting the meters.
The meter position for a 15 mm diameter meter shall be constructed to include 20 mm x 15 mm bushes at both sides of the meter position with a 200 mm (clear effective length) distance piece of 15 mm tube placed in between (refer to Fig 3). The tube shall be hollow with conspicuous holes drilled through the body. A long screw connector shall be provided immediately after the bush at the delivery side. The meter position for meter of all sizes shall also be similarly provided with corresponding fittings of appropriate sizes. The length of the distance piece should be as follows (refer to Fig 4):-
If a section of copper pipe is used either before or after a water meter position, the section of copper pipe between the water meter position and the first pipe clamp should be jointed by screwed joints.
When the applicant submits the vertical plumbing line diagrams (VPLD), he/she will also be required to submit the layout and elevation plans of the meter rooms/boxes with dimensions, including the width and height of the entrances (door openings in case of meter boxes) for the
Water Authority’s approval. All water meters, including vacant meter positions and check meter positions, shall be arranged in groups and housed in meter rooms or meter boxes. The meter rooms/boxes shall be used solely for housing water meters to protect them against exposure to weather, falling objects and other undue external interferences. They shall not be used as store rooms/boxes, etc. No other building services such as drainage systems, fire hoses, E&M installations (equipment, cables and ducting, etc.) shall pass through or be placed inside the meter rooms/boxes except lighting, ventilation and drainage, etc. solely to facilitate meter reading and maintenance of water meters. Unless otherwise accepted by the Water Authority, a typical meter room/box shall comply with the following requirements:
- for meter rooms, the minimum distance between the outward face of the meter group and the wall/door opening directly opposite the meter group shall be 1000mm and there shall be no obstacles in between. Besides, if the door to the meter room is to be opened at an inward position and it is at the opposite side of the meter group, the minimum perpendicular distance between the outward face of the meter group and the door (the point on the door that is nearest to the meter group) when it is fully opened shall be 600mm;
- the clear width and height of the door entrance to the meter room shall not be less than 800 mm and 2000 mm respectively. The arrangement of the meter position(s) and the door opening of the meter box shall be arranged in such a manner that staff of the Water Authority would not be required to lean inwards to take meter readings or carry out maintenance works. For meter boxes, the clear depth measured from the outside face shall not be more than 800mm;
- when the meter room is occupied for taking meter readings and/or maintenance of water meters, the illumination shall not be less than 120 lux at meter positions and the mechanical ventilation shall not be less than 6 air-changes per hour;
- an entrance located at communal area for safe, free, and uninterruped access to the meter room/box shall be provided;
- provision of adequate drainage inside the meter room and the meter box positioned at floor level shall be made;
- the door(s) to the meter room/box shall not be equipped with any self-closing device. The lock of the door to the meter room shall be located at a level between 0.9m and 1.1m above the finished floor level. The door to the meter room shall be equipped with handle to facilitate door opening. The door handle shall be either in the form of long cylindrical or spherical shape to facilitate handling. Covered or flat sectioned handles shall not be used;
- If there are more than one water meter room/box inside a building block, master-key locks shall be used at all meter rooms/boxes and a duplicate master key for the Water Authority or his/her staff’s sole use shall be kept at the management office. In case there are more than 300 water meters or 30 meter rooms/boxes, two duplicate master keys shall be kept for the sole use of the Water Authority.
- for high-rise building blocks, water meters shall be installed in meter rooms/boxes. For low-rise buildings with fenced-off area, water meters shall be installed in meter room(s)/box(es) located at the boundary and shall be accessible from the public area;
- meter rooms/boxes inside market/commercial complex shall be positioned in areas with clear access and with no risk of being obstructed by hawkers, etc.
Upon completion of the water meter installation inside a meter room/box, the LP shall install a permanent display board at the wall/door inside the meter room/box showing the location and elevation of the meter positions. The top of the board shall not be higher than 1500 mm above the floor level and the bottom of the board shall not be lower than 500 mm for an individual meter above the floor level. This display board shall be constructed of durable plastic or corrosion-resistant plate engraved with words and diagrams in black on light colour background. The wordings should be of font size not less than 18 pt. Details of this display board shall be submitted by the applicant as part of the VPLD for the Water Authority’s approval. This requirement can be waived for small meter boxes accommodating 3 meters or less.
Within two weeks after completion of the water meter installation, the LP shall submit as-built plans of the meter arrangements, the completed Meter Installation Table (MIT) and Part IV of the Form WWO 46 where amongst others the LP undertakes the correctness of the meter positions. The applicant/developer and the Authorised Person shall also countersign in Part IV of the Form WWO 46 to indicate their satisfaction of the correctness of the meter positions.
For meters arranged in groups, no meter position shall be lower than 300 mm nor higher than 1500 mm above the floor level. This requirement is also applicable for water meters installed inside meter boxes. For Housing Department estates where corridor meter arrangement is chosen and accepted, individual meter positions shall be at a suitable height not less than 750 mm but not more than 1500 mm above the floor level.
The meter position of a building supply to a construction site shall be provided within a meter room or meter box located at the hoarding recess area so that reading and maintenance of the meter can be carried out outside the construction site. Safe, free and uninterrupted access to the meter room/box should be provided and maintained at all time. Same meter room or meter box location arrangement should be applied to other sites which may induce unnecessary safety risk on meter reading, such as car dump sites, sites for recycling works and sites for short term tenancy. The door of the meter room or meter box shall be made of chicken-wire or provided with see-through glass panel. Details of the meter room or meter box are subject to the approval of the Water Authority.
For a meter installed in a landscape area, it should be installed above ground level with a clear working headroom not less than 2m. A safe pedestrian access to the meter position should be provided.
When the meters are sited at roof level, fullway gate valves shall be fitted before meter positions. For connections up to and including 40 mm diameter, a loose jumper type stopcock shall be provided and placed with spindle in the vertical position at each meter position on the inlet side of the meter where the meter is not sited at roof level and where the pressure is considered adequate. For connections larger than 40 mm diameter, a fullway gate valve shall be provided before the meter position and a non-return or check valve fitted on the delivery side as close as possible to the meter position.
The following practice should be adopted in plumbing work design for meter positions:-
- the fittings at the meter position should facilitate easy installation and removal of the water meter without the need to work on other pipes;
- the pipework at the meter position should be securely fixed to support the weight of the water meter and to resist any torsion, bending and tension during the installation and removal of the water meter.
The Water Authority had implemented the master metering policy after 31 December 2005. The purpose of introducing master metering is to detect water leakage and unlawful taking of water before meters. A master meter room to house the master meter and its by-pass arrangement should be provided as close to and within the boundary lot as possible. The details of implementation of the policy are as follows:
- For all new developments, except single detached village type buildings and single block buildings, plumbing designers shall be required to provide master meter room with master meter position(s) in the plumbing, submit undertaking Form WWO 542 for the consumership(s) of master meter(s) and arrange licensed plumber to install master meter(s). These requirements shall apply to all plumbing proposals first submitted to the Water Authority after 31 December 2005.
- Notwithstanding the paragraph (a)(i) above, for development with more than 1 detached village type building, master meter is not required if the total length of underground and concealed pipes does not exceed 15m.
- The water supply connection arrangement for fresh water supply, fire service supply and Temporary Mains-water for Flushing (TMF) supply will be as shown in the Fig. 27 and 28.
- The master meter will substitute current requirement of check meter positions in all fresh water and TMF inside service and fire service. There will be 1 master meter installed in each set of connection points at the lot or building boundary. Twin or dual main connections are regarded as one set of connection points.
Downstream of the master meter,
- for fresh water supply
all individual domestic premises, water usage points or group of water usage points shall be metered with separate meters.
- for fire service
there shall be no other meter.
- for TMF supply
there shall be 1 communal TMF meter to each individual block of buildings.
- To ensure accuracy of master meter, the plumbing designer shall provide two lengths of straight pipe, one upstream and one downstream of the master meter. The length upstream and downstream should not be less than 10 times the nominal diameter of the master meter and 5 times respectively.
- To facilitate replacement of master meter(s), a 100mm diameter by-pass arrangement should be provided for future maintenance of water supply during meter replacement. (refer to Fig. 28 and Fig. 30).
- To facilitate installation, inspection, reading, service, and replacement of master meter(s), the plumbing designer shall house master meter(s) and associated by-pass(es) in meter room(s) preferably with at-grade access where feasible. Please refer to Fig. 29-33 which indicate the design considerations for the at-grade master meter room.
- If the watermain is to be laid underneath internal roads which is scheduled to be handed over to government within 5 years after completion, master meters should be installed for each separate connection group for the buildings/podia at their respective boundaries.
- If the handing over is scheduled longer than 5 years after completion, the said master meter positions mentioned in (h)(i) are still required but temporarily bridged over by short pieces. On top of this, master meters are also required at the estate’s boundary (refer to Fig. 34)
- Fire service supply needs to be unaffected by potable supply interruption as far as practicable. Also, the metering characteristics of both supplies are different. Therefore, fire service needs to be separate from the potable supply right at the lot boundary. A typical configuration of master meter is shown in the Figs. 27 and 28.
Check meter positions shall be provided in fresh water and TMF inside service and fire service.
For check meter of 100 diameter or smaller, a straight length of pipe of 5 x D (where D is the nominal bore of the meter) should be provided upstream of the check meter position and a straight length of pipe of 2 x D at downstream. For check meter of diameter larger than 100mm, the straight lengths upstream and downstream are 10 x D and 5 x D respectively.
The designer should provide minimum horizontally perpendicular and longitudinal working clearances at each check meter position. The table below stipulates the minimum horizontally perpendicular working clearance, meaning the shortest distance between the longitudinal centre line of the check meter position and a wall or any edge of a door when opened.
The minimum longitudinal working clearance between both ends of meter flanges of the check meter position and a wall or any obstruction should be 200 mm.
Pipes and fittings shall conform to the relevant British Standard as listed on WSD webpage. The following table summaries the different pipe materials that are commonly used in water supply systems:
The use of unlined GI pipes and fittings as fresh water inside service in new buildings and upon renewal of the plumbing installations in existing buildings is prohibited. However, this requirement does not apply to pipes and fittings installed prior to 23 December 1995, i.e. before the enforcement of the relevant section provided in Regulation 19 of WWR. .
The Water Authority may also accept pipes and fittings of other standards equivalent to the British Standard.
Application for Approval of Water Supply Pipes and Fittings
Every pipe or fitting shall be of the British Standard in accordance with the WWR.
Water supply pipes and fittings accepted by the Water Authority for installation in inside services or fire services should be under one of the following categories:-
- Water supply pipes and fittings marked in accordance with the appropriate British Standard and bearing British Standards Institution Kitemark;
- Water supply pipes and fittings accepted by the Water Regulations Advisory Scheme of
U.K. for compliance with the requirements of The Water Supply (Water Fittings) Regulations/Scottish Water Byelaws in UK.;
- Water supply pipes and fittings accepted by this Authority as suitable for use locally in conformity with the WWO and WWR.
To obtain approval for the installation and use of pipes or fittings in inside service or fire service covered by the WWO/WWR from this Authority, the applicants are required to produce one set of certification or test reports confirming their compliance with the relevant British Standard as listed on WSD webpage from either (a) the British Standards Institution,
(b) the U.K. Water Regulations Advisory Scheme or (c) accredited laboratories acceptable to this Authority.
The acceptance letters for pipes and fittings are issued against the products irrespective of the suppliers or suppliers' agents. For a change in the supplier or supplier's agent for a product by the same manufacturer, it is not necessary to make a re-submission.
Fresh Water Supply
The treated fresh water provided by the WSD complies fully with the drinking water standard according to the guidelines of the World Health Organization. However, in order to ensure that consumers can enjoy good quality of water at the taps, building owners have to maintain their plumbing systems properly as well. To encourage the building owners to do this, the WSD launched the Fresh Water Plumbing Quality Maintenance Recognition Scheme (which has been renamed Quality Water Recognition Scheme for Buildings (QWRSB) since January 2008). QWRSB were re-titled "Quality Water Supply Scheme for Buildings - Fresh Water" in March 2015.
All fresh water supplies to inside service shall be metered. All domestic supplies and concessionary supplies shall be separately metered. For different usages of concessionary supplies, please see Section 6.2.9.
Cleansing and Disinfection of Newly Installed Fresh Water Inside Service
Under the provision of Regulation 7 of WWR, a consumer or the agent shall be responsible for keeping an inside service clean. To this end, the consumer or agent concerned shall clean and disinfect newly installed fresh water inside service before it is put into use. Besides, after repair or maintenance of fresh water inside service, if there is a possibility that extraneous materials can get into the inside service, the inside service shall be cleaned and disinfected before water supply is resumed. The guidelines on how to clean and disinfect the fresh water inside service and the requirement of water sampling test are set out in WSD Circular Letter No. 2/2012, 1/2015 and 5/2015.
Water supply to premises can be effected in one of two ways:-
- direct supply system, where it is feasible to supply water by gravity from the mains.
- indirect supply system, where it is necessary for the water supplied to the inside service in highrise buildings be boosted in some ways like a sump and pump system or a hydro pneumatic pump system which is usually provided to the topmost floors after a roof storage tank.
All plumbing works before meter positions shall be exposed or laid in a proper service duct to facilitate inspection and repairs. Provision shall be made for checking leakage from any plumbing work laid underground.
If the connection is not laid in an exposed manner at the lot boundary, then it shall be laid underground with an adequate cover. For carriageway a minimum cover of 1000mm is usually required. Watermains located in Industrial Area or beneath footpaths/verges/cycle tracks whenever there is a possibility of vehicles parking or running on them should be laid with the same cover as those under carriageways. All underground plumbing works (government projects are exempted except projects of Housing Authority) will be inspected by the Water Authority before it is backfilled or covered up.
Direct Supply System
The meters shall be sited at convenient locations in communal area.
Indirect Supply System
The meters shall be sited at roof level or at other convenient locations.
Use of Water Purifiers / Filters
The quality of the water supplied by the WSD up to the customer's building or the lot boundaries of the building conforms to the Guidelines for Drinking-water Quality recommended by the WHO and is stringently monitored through extensive sampling at treatment works, distribution networks and customers' taps. The WSD does not normally approve nor recommend installation of water filters. The reason is that they may become an ideal breeding ground for bacterial growth giving rise to health hazards if they are not properly maintained.
Water purifiers / filters shall not be used without the permission in writing of the Water Authority. As the treated municipal water supply to the whole territory of Hong Kong conforms chemically and bacteriologically to the Guideline Standards for Drinking Water of the World Health Organisation and is monitored closely by extensive sampling at treatment works, distribution networks and consumers' taps. the Water Authority does not normally approve nor recommend the installation of water filters in domestic premises because they can give rise to health hazards if they are not properly maintained.
Domestic water purifiers / filters must not be connected directly to the mains supply because of the possibility of contamination. They may be installed in an indirect supply system via the storage tank where there is no possibility of contamination of the mains supply, or of the supply to other premises, e.g. in a communal inside service a separate storage tank would be necessary.
As contaminated water in the filter can backflow to communal water supply system or upstream, the Water Authority does not recommend the installation of any water filter. When there is installation of any domestic filter or water filter incorporated in water using apparatuses (such as drinking fountain etc.), precautionary measures should be taken to ensure proper backflow prevention incorporated or installed where appropriate. The Water Authority does not require any test results of the filters before installation, i.e. "general acceptance" is not required and will not be given.
Despite the above, customers should carry out proper maintenance of water tanks and pipes in their buildings so as to maintain the water quality and to reduce the possibility of pollution arising from the use of water filters. Regular maintenance of domestic water filters is also equally important.
Use of Washing Machines / Dish-washing Machines
Where there is no possibility of back siphonage resulting in contamination of the water supply, washing machines / dish-washing machines may be connected directly to the mains. Washing machines / dish-washing machines with submerged inlets must not be connected directly to the mains and should be supplied with water via a storage tank. A ventilation valve and reflux preventer shall be installed at the supply inlet at a level above the top edge of the washing machine / dish-washing machine.
Provided that the construction site is within easy reach of the Waterworks distribution system, metered supply may be given for construction purposes.
For individual construction sites, metered water supply may either be tapped directly from the mains or from a fire hydrant. In cases of boring works for site investigation and location of sites are not confined to one particular area or the limit of the works area makes it technically impracticable for the installation of building supply meters, the applicant may apply for a meter adaptor to draw a supply from any fire hydrant near to the works area.
Supply to Temporary Structures and Modified/Converted Structures
Metered supply will be given to temporary structures and modified/converted structures, provided that:
- The water supply is adequate and available in the proximity;
- The inside services are designed and constructed properly, such that the requirements under Waterworks Ordinance are satisfied; and
- The consumer/agent gives an undertaking to pay and accept the responsibility for the custody and maintenance of the inside service.
In addition, in order to enable the Water Authority to carry out its functions under WWO and WWR, the premises shall have individual access, proper drainage system and bear a proper postal address.
In all cases, the provision of metered water supply by the Water Authority will not confer any legal implication on the structural status of the premises nor carry any effect of precluding action being taken in respect of the structure by another authority.
Supply for Cooling / Air-conditioning / Humidification Purposes
Water supply shall not be used for any heating, cooling or humidification purposes except with the approval of the Water Authority. Uses of mains (fresh or salt) water may be given for cooling / air-conditioning / humidification purposes to meet the following requirements:
- closed circuit cooling systems for any purpose where operational losses are negligible and no water is rejected to waste;
- cooling systems involving no loss through evaporation and where all the water is re-used after cooling for an industrial process; (The normal trade requirement must not be less than that required for air-conditioning/cooling purposes at peak load);
- evaporative cooling systems essential to an industrial process, whether this be for cooling or for air-conditioning purposes and provided that system losses arise from evaporative only;
- evaporative cooling/air-conditioning/humidification systems for essential purposes other than industrial processes provided that system losses arise from evaporation only;
- humidification essential to an industrial process(e.g. the spraying of a fine mist in textile weaving plants).
The use of mains water in evaporative type plants for essential purposes other than industrial process is limited to those cases where the cooling / air-conditioning / humidification system is absolutely necessary. An example of such case is the use of mains water for the evaporative type air-conditioning system to serve those areas in hospitals, such as the operating theatres, intensive care units, mortuary etc., where air-conditioning is essential for operation requirement. Other examples are the provision of evaporative type cooling system for cold storage purpose or laboratory testing; and air-conditioning / humidification system for major computer facilities, art gallery or testing laboratory. The type of evaporative plant used should be of an enclosed design from which wastage of water by splashing is prevented.
Prior to installation of the fresh water cooling towers, the contractors should apply for participation in the “Fresh Water Cooling Towers Scheme for Air Conditioning Systems” (the Scheme) operated by the EMSD. In the design and installation of the fresh water cooling towers and the making of the associated water supply connection, the contractors are required to comply with the “Code of Practice for Water-Cooled Air Conditioning Systems” of the Electrical and Mechanical Services Department (EMSD) and the requirements of the WSD respectively. For more updated information, please refer to EMSD's website http://www.emsd.gov.hk/
Concessionary Usage of Mains Water
Approval to use government water supply for the purposes listed below can normally be given on concessionary basis when the territory is on full supply, subject to adequacy of the local water supply and distribution system. Such approval will be withdrawn if in the opinion of the Water Authority the supply situation requires it.
The concessionary usages are as follows:
- initial filling of swimming pools and paddling pools and subsequent annual refilling and make-up purposes, provided that the water is fully re-circulated.
- initial filling of model boat pools and subsequently refilling once in every two months in summer and once in every three months in winter.
- initial filling of fountains and water features and subsequent make-up purposes, provided that the water is fully re-circulated.
- initial filling of artificial lakes in public recreation areas and subsequent make-up purposes.
- watering flower-gardens at public housing estates, Home Ownership Schemes, Private Sector Participation Schemes, schools, institutes, community service centres, large private developments, amenity areas alongside highways, and gardens maintained by government departments, including traffic islands and sitting out areas, where the aggregate area of the flower beds is not less than 30 m2.
- point supply: the layout of the supply points should be such that each point will serve an area within the sweep of a 20 m-long hose, and the number of supply points shall be kept to a minimum.
- ‘drip feed’ irrigation system: where the aggregate area of flower beds exceeds 30 m2, one connection point should normally be given. Additional connection point may be given only when physical barrier exists preventing extension of the drip feed irrigation system and the distance of two successive connection points exceeds 40 m. This category of concessionary usage must be supplied off tank.
- watering plant nurseries.
- irrigating large landscaped areas in new towns. This category of concessionary usage must be supplied off tank.
- watering large area of grass in sports fields such as tennis courts, bowling greens, cricket pitches and football pitches. Supply may be permitted only if there is no practical alternative.
- internal cleansing in buildings such as washing down floors and staircases, refuse chutes and lifts in large blocks of flats and offices; for essential floor cleansing in factories, hawker bazaars, markets, abattoirs and public latrines; and for washing down buses, railway rolling stocks, aircraft, cargo containers and government refuse vehicles, bins and handcarts; for car-washing in garages and car-parks. This category of concessionary usage must be supplied off tank.
- operation of mechanical washing vehicles such as mechanical street-cleaners belonging to government departments.
- cleansing for the purpose of air pollution control in respect of smoke or gas emitted from plants or equipment provided that water loss is due to evaporation only. This category of concessionary usage must be supplied off tank.
- dust suppression essential to an industrial process either from an operation standpoint or on grounds of air pollution control. Recycling of water is required unless it is demonstrated to be impracticable. This category of concessionary usage must be supplied off tank.
The purpose of having some of the concessionary supplies to be supplied off tank is to prevent contamination of the supply source through back siphonage. Similar provisions should also be considered for other categories. For concessionary supplies under (v)(a),(vi),(vii) & (viii), where the installation takes the form of supply standpipe and that a hose will only be connected to the draw-off point when water is drawn, an anti-vacuum valve and a non-return valve may be installed at the draw-off point in lieu of a water storage tank for preventing back siphonage because the potential hazard of water contamination is relatively low. However, every draw-off tap that is freely accessible by the general public should be kept under lock and key.
Installation of water points for internal cleansing of open yards and for other miscellaneous domestic purposes in private houses of bungalow type or the like can be permitted as part of the domestic supply. This will not be taken as a concessionary supply.
Wheel-washing for lorries in construction and reclamation sites is categorised as construction supply. This use is permitted provided the water is fully re-circulated.
Hot Water Systems
A loose jumper type valve shall be fitted on the inlet of the water heater if a non-return valve is not incorporated in such water heater, but this requirement does not apply to an electric water heater of the thermal storage type satisfying HKWSR Clause 5.11.
Every system incorporating an unvented electric water heater of the thermal storage type shall be provided with:-
- a supply pipe that branches off from the feed pipe at a point above the top of the water heater, or some other device to prevent the water from draining down from the water heater if there is a failure at the source of water supply;
- an anti-vacuum valve or some other device to prevent heated water from being syphoned back to the supply pipe; and
- a vessel to accommodate the expansion of heated water where that expansion is constrained by a non-return valve or some other device, incorporated at the inlet of the water heater.
Pressure type thermal storage heaters other than unvented electric thermal storage water heaters shall be supplied from a separate mains water storage cistern, no matter what the pressure at inlet point should be, except these are installed in flats supplied through the indirect or sump and pump system. They shall be provided with a vent or an expansion pipe taken from its highest point and discharge in the atmosphere above the storage cistern at sufficient height to prevent a constant outflow of hot water therefrom.
When the factory test pressure of the heater is less than 1½ times the maximum static water pressure at the mains water supply point then, for premises on direct supply, a separate mains water storage cistern of 45 litres capacity shall be provided for each flat to supply the hot water apparatus.
For flats supplied from the roof storage cistern (of an indirect or sump and pump system), no separate storage for hot water apparatus will be required but the supply to the apparatus shall be by a separate down feed supplying the apparatus only unless the flats on the indirect system are supplied through an oversized down feed pipe, for which case the pipe supplying the hot water apparatus shall be branched from the down feed at a point above the top of the apparatus.
Some heaters, such as gas geysers and instantaneous type electric water heaters, may require a minimum pressure and flow for their proper functioning. When these heaters are to be installed, their suitability shall be checked against the available pressure and flow, especially for the uppermost floors served by the direct system or the indirect system.
If mixing valves, water blenders or combination fittings are to be used, the cold water supply to these fixtures shall be drawn from the same source that supplies the hot water apparatus in order to provide a balanced pressure and to obviate the risk of scalding should the supply at the source fail or be restricted for any reason.
The Electricity (Wiring) Regulations require that installation of unvented electric thermal storage type water heaters shall be carried out by a Grade R registered electrical worker. The safety devices of unvented storage type electric water heaters are under the control of the Electric Products (Safety) Regulations administered by the Electrical and Mechanical Services Department.
For the installation of unvented electric thermal storage type water heaters, the drain pipe provided for the relief valves shall be installed in such a manner that the water released from the valves shall be discharged to a safe and visible location.
The Water Authority may consider acceptance of plumbing installation and a supply to be given without heaters installed on the following conditions:
- If VPLD indicates that heaters will not be installed but plumbing details are shown to provide supply points for heaters, a written undertaking must be obtained from the architect/developer with full description of the type of heaters intended to be installed in future so that VPLD should be checked and approved to comply with Waterworks requirements for the installation of the particular heaters.
- If heaters are shown on VPLD but cannot be installed in place ready for final inspection, an advance written undertaking should be obtained from the architect/developer giving a prescribed date for the heaters to be installed.
- A warning plate should be secured in a proper and conspicuous place as near to the heater position as possible and etched with the following instruction in both English and Chinese:
The Water Authority shall carry out re-inspections to the premises 6 months after the installation of meters to check if the correct type of heaters have been installed.
Centralized Hot Water System
All centralised hot water systems utilising a boiler and cylinder (direct system) (Fig 12), or calorifier (indirect system) (Fig 13), shall be provided with a vent or an expansion pipe taken from the highest point of the cylinder or calorifier, or if a secondary circulation system, from the highest point of such system. In either case the vent or expansion pipe shall discharge to the atmosphere above the storage cistern at sufficient height to prevent a constant outflow of hot water therefrom. Under no circumstances shall safety valves, air valves or relief valves be used as a substitute or replacement for a vent or expansion pipe nor should any control valve be installed on the vent or expansion pipe between the highest point of the cylinder or calorifier, and the free end of such pipe.
When a centralised hot water system of the boiler/cylinder or calorifier type is installed, in addition to the vent pipe as required above, a safety valve or pressure relief valve shall be provided to the boiler or to the primary flow pipe as close to the boiler as possible. Such valve shall be set to discharge when the pressure in the boiler exceeds 35 kPa above that of the static pressure of the system.
The cold feed pipe to the boiler/cylinder or calorifer shall not be used for other purpose. If mixing valves, water blenders or combination fittings are to be used, the cold water supply to these fixtures shall be drawn by a separate down feed from the same water storage cistern supplying the hot water system. This outlet shall be slightly lower than the feed to the hot water system in order to provide a balanced pressure and obviate the risk of scalding should the mains supply fail or be restricted.
A screwed plug with a removable key shall be provided at the lower part of the system for the purpose of draining down or emptying the system. No stop valve shall be installed in the primary flow or return pipes except when a vent pipe is connected to the boiler and such installation shall only be made under skilled supervision.
No tap or other means of drawing off water (other than a screwed plug with a removable key for emptying the system for cleansing and repair) shall be connected to any part of the hot water system below the top of the hot water cylinder in such a way that the level of water in the cylinder can be lowered. In a hot water system comprising more than one storage cylinder at different levels, this requirement should apply to the lowest cylinder.
The hot water taps shall be fixed at a distance from a hot water apparatus or from a flow and return system not greater than 12m for pipes up to and including 20 mm diameter, 8m for pipes up to 25mm diameter, and 3m for pipes above 25 mm diameter.
To avoid waste of water when repairs are being effected, a stop valve shall be fitted on the cold feed pipe at the outlet from the storage cistern. If the storage cylinder is installed at a lower floor, and additional stop valve shall be fitted near the inlet to the cylinder. Such stop valve as provided shall have loose keys or hand-wheels which shall be kept in a safe place to prevent unauthorized interference.
To ensure proper installation, a licensed plumber should be engaged to install the dispenser and conduct a lead check on the soldering material at the inlet inside the dispenser to confirm that it is lead-free before the installation of the dispenser. Lead check is a simple method to test the presence of lead on metal, wood or paint by using lead test swabs or papers.
Flushing supply may be obtained from the government supply system or from other sources. For inside service using government water supply for flushing, it should comply with the Waterworks requirements. The inside service for flushing water supplied from privately owned wells, nullah intakes, stream intakes or other water source need not comply with the Waterworks requirements. If it is foreseen that flushing supply from government supply system is likely to be required, the flushing system should comply with the Waterworks requirements in order to minimise the modification work required at a later stage.
All flushing water supply systems shall be kept separate from water supply systems. A water meter shall be installed at each flushing system receiving a temporary mains fresh water (TMF) supply. TMF flushing supply is normally given to the entire building through a communal meter. Individual units with independent flushing supply systems will involve a very complicated plumbing arrangement which is both expensive and technically difficult because of the need to comply with the off-tank supply requirement. Hence, application for flushing supply should be submitted by a representative of the building and application for individual units is not entertained.
Salt water flushing supply is also subject to the bulk application but it is not metered. However, a meter position shall be provided for consumption check and waste detection purposes. It shall be close to the lot boundary or close to the point of connection from the internal distribution mains whichever is applicable.
A separate water storage tank shall be provided for flushing purpose. Every water closet, latrine shall be provided with a flushing cistern which shall have an overflow terminating in a conspicuous position.
For existing buildings for which permission is given to use government water supply in lieu of private supply for flushing purpose, any existing unsuitable flushing apparatus shall be replaced with proper apparatus within a reasonable period before a government supply is given.
It is the requirement under Buildings Ordinance that all new buildings shall be provided with a system of plumbing for the supply of water for flushing purposes and every part of such system of plumbing (including the storage tank) shall be constructed of material that is suitable for use with salt water.
Salt Water Supply
Salt water supply to premises can be effected in two different ways (Fig 14).
Direct Supply to a Roof Storage Tank
This system is used when the mains supply pressure is adequate. The storage tank is used to guard against contamination, accidental interruption of supply and to even out peak demands.
Sump and Pump System
This system is used when the mains pressure is insufficient to effect a direct supply to the roof tank. In this system, salt water is supplied from the mains to a sump tank from which it is pumped to a high level storage tank whence it gravitates to the draw-off points. Direct boosting from salt water mains is not permitted.
Temporary Mains Fresh Water for Flushing (TMF)
Mains fresh water may be given for flushing only in cases where the Water Authority is satisfied that there is no suitable alternative. Such flushing supply should be given on a temporary basis and shall revert to salt water supply when this becomes available.
When salt water becomes available in areas containing premises using fresh water as a temporary alternative, the Water Authority will inform the consumers that permission to use fresh water will be withdrawn in 3 months' time and salt water will be provided in lieu. Consumers will also be informed of the estimated cost of the salt water connection.
In the case of a TMF supply to be provided as the alternative source to augment an existing non-government supply, the water storage tank shall be constructed in accordance with Fig 15 (Drawing No W1543/5B).
Flushing devices can be classified broadly into 2 main types viz. the valveless syphonic type and the valve type. The current WWR require that flushing cisterns shall be of the valveless syphonic type capable of giving a flush between 7.5 and 15 litres. The practice of accepting only valveless syphonic type cisterns is mainly to prevent leakage of water into the toilet bowl, as in the past, the water-tightness of most valve type flushing devices was often a problem. However, a disadvantage of valveless syphonic type cisterns is that they require a comparatively larger volume of water to generate the necessary flushing effect and a cistern volume of 7.5 litres is seen as the practically minimum requirement. With the improvement in design and material, valve type flushing devices have become more reliable in their performance. A major advantage of valve type flushing devices is that they can give instantaneous flushing even with a relatively smaller volume of flushing water. This helps reduce water required for flushing. Valve type flushing mechanism also permits the design of "dual-flush" cisterns in which the volume of water to be discharged from the cistern can be selected by choosing either a "full-flush" or a "half-flush" depending on need. This allows further reduction in flushing water requirement.
Therefore, by means of the WSD Circular Letter No. 4/2000 of 31 October 2000, the Water Authority relaxes the waterworks requirements in respect of the flushing mechanism and minimum flushing volume, as follows:
- the use of valve type flushing devices (mechanical or sensor type with single flush or dual flush) in addition to valveless syphonic type flushing apparatuses; and
- the use of flushing devices which are capable to give a single flushing volume of less than 7.5 litres.
An essential requirement on the relaxation on the use of valve type flushing devices is that the design flushing volume should be compatible with the bowl to ensure effective clearance of waste by a single flush. A good management system ensuring frequent inspection and cleaning of filters of the flushing valves is required. In case the flushing valve with a built-in strainer in place of a filter is adopted, the designer must ensure that the strainer can be readily inspected and cleaned. Otherwise, the installation of a filter readily accessible for inspection and cleaning is suggested.
Identification of Internal Fresh and Salt Water Mains within Large Developments
To avoid connecting the internal fresh water pipe to salt water pipe by mistakes, the following guidelines shall be closely observed:
- when designing the plumbing proposals of large developments with internal fresh and flushing water mains to be laid at the same location, different pipe materials and/or different sizing for the fresh and flushing water mains should be used so that each of the two pipes systems can be easily identified and distinguished from the other on site.
- before connecting newly completed pipes to internal fresh or flushing watermains under supply, utmost care should be exercised in identifying and distinguishing each of the two pipe systems. The identification can be done by following step by step a planned operation procedure and test methods such as chemical tests. It is also important that any newly laid pipework should not be put into use before it has been inspected and approved by the Water Authority.
These good practices should also be applied to other similar types of multi-system pipeworks such as those with a private sea water cooling system.
The Director of Fire Services is responsible for approving proposals for installations of or alterations to fire services. The fire service in a building such as the choice of the fire-fighting system and its capacity must satisfy the requirements of the Fire Services Department (FSD). Only the plumbing system of the fire service is subject to the requirements of the Water Authority.
For installations which are to be connected to government mains, the method of supply and the materials used must be subject to the approval of the Water Authority and their installation should comply with the Waterworks requirements. The fire service should be designed to guard against contamination, waste and misuse.
As no charge is imposed on the consumption of water used for fire fighting and hence no chargeable meter will be installed for the fire service. However, check meter positions shall be provided for consumption check and waste detection purposes. It is also to remind that use of water from fire service for purposes other than fire fighting is prohibited.
The check meter position shall be close to the lot boundary or close to the point of connection from the internal distribution mains whichever is applicable. A fullway gate valve and a non-return valve have to be installed on the fire service as close as possible to the government water supply connection.
Every pipe or fitting shall be of the British Standard in accordance with the Waterworks Regulations, Cap. 102A.
Pipes on a fresh water fire service shall be made of ductile iron, galvanized wrought iron, galvanized steel or copper of approved standards. Consideration can be given for the use of wrought iron pipe and black steel pipe without being galvanized, upon application, for a fresh water fire service after a positive air break (i.e. fire service tank or sump tank). Pipes and fittings on a salt water fire service shall be ductile iron or galvanized steel with suitable lining and fittings capable of withstanding the corrosive effect of salt water.
Supply Types and Arrangements
Fire service supply may be from a fresh water or salt water source and it must be from an independent connection. The fire service must be entirely independent of other water supply arrangements within the building or development concerned. A salt water installation may be “primed” with fresh water to inhibit corrosion etc. Such priming arrangements must be approved by the Water Authority prior to installation.
All pipeworks before check meter positions shall be exposed or laid in a proper service duct to facilitate inspection and repairs. Provision shall be made for checking leakage from any pipeworks laid underground. If the connection is not laid in an exposed manner at the lot boundary, then it shall be laid underground with an adequate cover. For carriageway a minimum cover of 1000mm is usually required. Watermains beneath footpaths/verges/cycle tracks should be laid with the same cover as those under carriageways.
The followings are some commonly used types of fire service systems:
Sprinkler / Drencher System
Sprinkler system (Fig 16) is an automatic system which comes into operation at a predetermined temperature. It is designed to:
detect a fire;
give an alarm;
attack and contain an outbreak of fire until the arrival of the Fire Services.
Drencher system is a system of pipes designed to operate either automatically or manually and provide a curtain of water over buildings which constitute a particular dangerous fire hazard e.g. tanks containing highly imflammable liquids.
A dual connection from the Government unrestricted supply ring main shall be provided for a fire service sprinkler / drencher system situated in the recognised Waterworks unrestricted industrial supply zone. Twin connections, one from an unrestricted supply main and one from a distribution main, will be provided for a fire service sprinkler / drencher system situated outside the recognised unrestricted industrial supply zone, where practicable.
Where it is not practical to connect the fire service sprinkler / drencher system to an unrestricted supply main, FSD may require the provision of fire service tank to serve as secondary source for the fire service installation. Depending on FSD’s requirements, a single or dual connection can be given to serve the fire service tank of secondary source.
No part of any fire service sprinkler / drencher system supplied from the Government mains shall be used for supplying any other services including other fire services including other fire service installations, e.g. hose reels, except that a common suction tank can be used for both sprinkler and hose reel systems. Any exemption from this requirement should have the endorsement of the Director of Fire Services.
Where direct connections to a sprinkler / drencher system are to be from the government mains, an additional butterfly valve, without stop screw and lock nut on handle and strapped in open position, shall be installed at a point on the supply pipe before the fire service inlet and as close as possible to the control valves of the connections.
Application for improvised sprinkler systems should be first submitted to the FSD for endorsement before it is submitted to the Water Authority for processing.
Hydrant/Hose Reel System
This system ensures that an immediate supply of water is available to any floor of a multi-storey building. Supply must not be fed directly from the government mains and the outlet should be housed in a glass-fronted cabinet secured under lock and key. The glass panel shall be of a frangible type and shall not exceed 1.5 mm in thickness, and that it shall be of such size and design so as not to cause any undue obstruction to the free use of the hose reel. Furthermore, a metal or plastic striker shall be provided in the vicinity of the cabinet for the purpose of breaking the glass panel in case of emergency.
Common tank arrangements for fire-fighting and flushing or other purposes are not acceptable when a government supply is involved. Where a building is to be provided with a non-government flushing supply and where it is proposed to feed the fire service from that supply, the applicant is advised to install an independent fire service system if it is envisaged that the fire service system may require to be connected to the government main at a later stage.
Street Fire Hydrant System
A street fire hydrant system serves as the secondary water supply for firemen during fire fighting operation. The system consists of standard pedestal type street fire hydrants installed along emergency vehicular access to a building.
Fire Service Ring Mains
Where in large industrial complexes a fire service ring main is required, this should be connected to an unrestricted supply main, if practical. In cases where this is not practical, a “dual” connection from the government ring main should be provided.
Fire service ring mains shall not be connected to or used for supplying any other service, except with the approval of the Water Authority.
Fire Service Installations for the New Territories Exempted Houses (NTEH)
FSD Circular letter No. 4/2006 has provided three sets of guidelines on specifications, installation and maintenance of fire service installations and equipment for the new fire safety requirements for NTEH applications.
Installation of Sprinkler System for Specified Commercial Buildings (SCB) / Prescribed Commercial Premises (PCP) under the Fire Safety (Commercial Premises) Ordinance Cap. 502 and Composite Buildings under the Fire Safety (Buildings) Ordinance Cap. 572
In line with the FSD's requirement to improve the fire service system of SCB, PCP and non-domestic portion of composite building with total floor areas exceeding 230m2, the following three options are acceptable to the FSD:
- addition of a new sprinkler system with water supplies in accordance with the requirements stipulated in para. 5.24 and para. 5.28 of the FSD’s Code of Practice for “Minimum Fire Service Installations and Equipment (revision 1994)”;
- addition of an improvised sprinkler system with its supply drawing from an existing FH/HR tank;
- addition of an improvised sprinkler system with direct connection to government mains.
For applications to install the improvised sprinkler systems stated in (b) & (c) above, the endorsement and referral from the FSD are required before any input is made by WSD’s District staff to process such applications. The FSD in thus the first stop in processing such applications.
For SCB, PCP and non-domestic portion of composite building with total floor areas exceeding 230m2, the provision of an automatic sprinkler system has been included as one of the requirements under the Fire Safety (Commercial Premises) Ordinance and Fire Safety
(Buildings) Ordinance. For those existing buildings/premises without such a provision, the 3 options above are acceptable for the provision of a sprinkler system. Installation of an improvised sprinkler system is often required due to structural and spatial constraints of the existing buildings.
Storage Cisterns,Water Pumps and other Miscellaneous
Storage Cisterns (or Water Tanks)
Storage cisterns may be made of fibre glass, reinforced concrete or other materials approved by the Water Authority. Reinforced concrete is the most common material used. Prior approval by the Water Authority must be sought when fibre glass tank is to be used. Fibreglass storage cistern for potable water shall be of an approved type or certified to contain no toxic materials and suitable for storage of potable water.
A water storage cistern shall be fitted with a ball valve and a fullway gate valve at the inlet in the case of a gravity supply. In the case of a pumped supply to a single cistern, the cistern shall be fitted with an automatic control switch and without any stop valve. In the case of a pumped supply to twin cisterns, each cistern shall be fitted with an automatic control switch and a stop valve for temporary isolation purpose. The ball valve or control switch shall shut off the supply when the water level is 25 mm below the invert of the overflow pipe or the warning pipe if there exists one. The invert of the inlet pipe or the face of the outlet nose of the ball valve shall be not less than 25 mm above the top of the overflow pipe. All overflow and warning pipes of potable water storage cisterns shall be constructed of non-metallic pipe materials. The invert of an outlet pipe from a water storage cistern with capacity less than 5,000 litres shall be at least 30 mm above the bottom of the cistern; this distance shall be increased to 100 mm if the capacity is 5,000 litres or more. The outlet pipe of every water storage cistern shall be provided with fullway gate valve. Provision shall be made for a drain-off pipe to enable the cistern to be emptied. The drain-off pipe shall be properly plugged or adequate means shall be provided to prevent any unauthorized operation of the control valve at drain-off pipe.
An overflow pipe shall be provided which shall discharge overflow water to a conspicuous position in a communal area easily visible and accessible by the occupants. The overflow pipe shall be at least one commercial size larger than the inlet pipe and shall in no case be less than 25 mm in diameter. No part of the overflow pipe shall be submerged inside the storage cistern. A grating and a self-closing non-return flap shall be provided at the overflow pipe outside the storage cistern. A warning pipe may be installed in addition to an overflow pipe. Except that a warning pipe can be of any size not less than 25 mm in diameter, it shall comply with all other requirements of an overflow pipe. The warning pipe shall be installed at a level below the overflow pipe and shall be extended to outside of the building periphery for roof cistern or outside the pump room for sump cistern.
Double sealed covers with locking devices so constructed as to prevent the ingress of surface water shall be provided for all storage cisterns other than cisterns for flushing and fire-fighting purposes. Storage cisterns shall be so positioned that they are free from obstruction and readily accessible via safe access for cleansing and to facilitate repairs. It shall be located so as to minimise the risk of contamination of the stored water.
When the storage cistern for potable water is to be placed adjoining to a storage cistern for non-potable water, a physical break shall be provided between the two cisterns, i.e. walls and slabs of the two cisterns must be separated while tie beams linking the cisterns for structural requirements are acceptable. The tie beams shall be constructed in such a manner that cross contamination of two cisterns via the tie beams is not possible.
All outlet pipes from the storage cistern should, whenever possible, be positioned at the opposite side to the inlet supply pipe to prevent stagnation of water.
Structural design of the cistern and its supports should be subject to the requirements of the Building Authority.
Cleaning of Storage Cisterns
Potable water storage cisterns should be cleaned regularly at least once every three months, or more frequently if necessary, in order to prevent the accumulation of dirt and rust which may lead to discoloured water and chokage of water meter. To facilitate cleaning of water storage cisterns, all internal surface of floors, walls (to full height) and soffits (except the cistern openings) of potable water storage cisterns should be lined with a white non-toxic smooth finish such as ceramic tiles. A notice plate/board should be provided to record the dates of cleaning of the water cisterns. The notice plate/board together with the cleaning dates records should be securely fixed at a conspicuous location easily accessible and visible by the residents and the building management staff.
The following steps outline the general procedures for cleaning of the potable water storage cisterns in buildings:
- the management office shall notify the affected occupants the date and time of cleaning, duration of supply interruption and expected supply resumption time at conspicuous location easily visible by the occupants.
- close the outlet valve of the cistern.
- empty the cistern through the washout pipe.
- thoroughly scrub and clean the cistern with fresh water.
- drain away the water.
- scrub out the cistern thoroughly with a solution of chloride of lime or bleaching power containing not less than 50 parts of chlorine in one million parts of water.
- rinse the cistern thoroughly with fresh water.
- refill the cistern with fresh water.
- the cistern is ready for use after the outlet valve is open.
Size of Storage Cisterns
The storage capacities of water tanks must be approved by the Water Authority. The proportion of capacity of sump tank to roof tank shall be in the order of 1:3 or as advised by the Water Authority.
In general the storage capacities are recommended as follows:
- Flushing Supply
- Domestic Water Supply Sump and pump system
- Trade/Commercial Water Supply
For industrial buildings, the entire internal service shall be supplied from storage tanks with separated outlets/downpipes feeding independent systems to serve separately the industrial and processing purposes and the other general and ablution appliances. These independent systems shall not be interconnected. The recommended capacity of storage tanks for industrial use is one-day demand.
For office buildings, theatres and other places of entertainment the provision of storage tanks will not be obligatory, and if storage is to be provided, this shall not exceed the capacity determined by the Water Authority.
Where a sump-and-pump system is used, it shall be provided with a duplicate pumpset. The pumping capacity of the pumps shall not be less than the designed out-flow rate of the storage tank being supplied.
All pipework connections to and from pumps should be adequately supported and anchored against thrust to avoid stress on pump casings and to ensure proper alignment. Consideration should be given to minimise noise nuisance to adjacent consumers when choosing a pump system.
Valves and Taps
Individual stop valves shall be provided at all draw-off points or at a series of draw-off points if situated close together.
Use of Pressure Reducing Valves (Fig. 21)
No part in the internal pipeworks shall be subject to excessive high pressure. In case of excessive high pressure, the provision of break pressure tanks at a suitable level of the internal supply system would be a positive and reliable means to reduce the water pressure. Alternately, pressure reducing valves may be provided in lieu of break pressure tank. Application for the installation of pressure reducing valve should be submitted to the Water Authority for approval on the basis of the merits of each individual case.
Whenever a pressure reducing valve is installed, a bypass arrangement shall be incorporated with the provision of a second pressure reducing valve, except for fire service installations, to enable isolation of any defective pressure reducing valve for repair and replacement when necessary. A pressure indicator shall be provided for pressure monitoring and the associated pipes and fittings shall be able to withstand the maximum pressure that may arise upon the failure of the pressure reducing valve.
A tee-branch valve refers to an isolation valve at a branch pipe and which is located close to the main pipe. To facilitate maintenance and repair, tee-branch valves shall be provided:
- for all underground water pipes.
- if the main pipe is a communal inside service.
- in a flushing system if the main pipe serves more than one domestic unit or commercial floor.
Hot Water Mixing Valves
Installation of hot water mixing valves may be approved provided that both the cold and hot water are drawn from the same source, i.e. both hot and cold water supplied from a common storage cistern, or under direct mains pressure.
When infra-red sensor operated automatic taps are used as inside services, a stop cock or gate valve must be installed at the upstream of each fitting for manual isolation of water supply.
Self-closing taps, of non-concussive type and of approved pattern, shall be used for the public or communal lavatory basins except for those in private clubs in which the use of screw-down tap is permissible.
The metal work of an inside service shall not be used as an earth electrode. The use of non-metallic pipes or fittings should not have had any effect on the earthing arrangement of the building. However, for some old buildings metallic water pipes might have been used to form part of the earthing arrangement. Under such circumstances, whenever an electrical insulation is to be introduced in the inside service, the applicant or his/her licensed plumber is advised to consult the registered electrician to confirm that the earthing arrangement in the premises/building is acceptable. If the earthing arrangement becomes substandard, then actions should be taken to comply with the Electricity (Wiring) Regulations.
Separate Metering in Existing Premises
The inside service shall be constructed from each flat to the existing common meter positions. The existing sump-and-pump system, if any, shall be provided with a standby pumpset unless this proves to be impracticable.
In an occupied building, a temporary by-pass arrangement as close to the delivery side of the meter as possible shall be provided to maintain water supply to various units of accommodation when plumbing work is being carried out on separate meter conversion. The temporary arrangement shall be such that the consumption is still measured by the bulk meter. This by-pass arrangement must be removed immediately after the new separate meters are fixed. The bulk meter shall also be removed if no longer required.
Authorizing Private Developers/Authorized Persons to Undertake Water Supply Connection Works
Developers and Authorized Persons are encouraged to employ approved contractors to carry out all or any of the following works:
- connection to the public drainage;
- provision of water supply connection;
- construction of run-in and repair of damaged footpaths.
This will improve developer's control of their development programmes. As reflected from a survey with Authorized Persons, the issue of Occupation Permits under this arrangement could be advanced by up to three months.
The common problems in the internal water supply systems are water quality complaints, weak supply pressure and seepage / leakage of water. The main causes of these problems are usually due to corroded pipes and/or uncleaned storage cisterns, choked pipes and/or unauthorized alteration of inside service, and leaking pipe or pipe burst respectively.
In this respect, the management office or the agent is recommended to:
- thoroughly clean every fresh water storage cistern and scrub with a solution of chloride of lime or bleaching powder at least once every three months;
- to conduct regular checks to the plumbing system to ensure that it conforms to the approved conditions;
- to rectify any corroded pipes and irregularities immediately.
No system can be guaranteed forever but its service life can be greatly improved by proper maintenance and identifying initial signs of defects before they have a chance of further propagation.
Regular maintenance of the internal water supply system will not only help ensure that the plumbing system performs as it is intended but also minimize the cost of repair work required to rectify the damage to the plumbing system.
A typical maintenance schedule is shown below for reference:
Pressure reducing valves
Check the pressure at the upstream and downstream of valve within acceptable limits
Clean the potable water storage cisterns under a proper cleaning procedure once every three months, or more frequently if necessary ensure no cross connection between water storage tanks of different natures
look for signs of leakage or overflow
check for stagnant water, e.g. dust on surface of water check conditions of cistern supports
confirm operation of overflow and warning pipes
ensure the cover is of double sealed type, under lock and effective in preventing ingress of water.