LCQ22: Water main burst incidents
3.5.2023

Following is a question by the Hon Joephy Chan and a written reply by the Secretary for Development, Ms Bernadette Linn, in the Legislative Council today (May 3): Question: It has been reported that in the evening of March 4 this year, a fresh water main at Lei Shu Road in Kwai Chung burst. As the Water Supplies Department (WSD) needed to carry out emergency repair, the fresh water supply to a number of housing courts in Kwai Tsing and Tsuen Wan districts was suspended for almost 10 hours, and the number of residents affected was estimated to be as many as 300 000. It is learnt that similar situations often occur in Southwest New Territories. In this connection, will the Government inform this Council: (1) of the following information of the fresh water main involved in the aforesaid incident: (i) the year in which it was last replaced, (ii) the time when last repair was carried out, and (iii) the expected time when the next repair will be carried out; (2) of the major reason(s) for the burst of the fresh water main involved in the aforesaid incident; the measures put in place by the WSD to prevent the recurrence of water main burst incidents in the same districts; (3) in order to tackle fresh water main burst incidents that may occur in the future, whether the WSD has designated locations in Tsuen Wan and Kwai Tsing districts for parking water wagons/placing water tanks for providing emergency temporary fresh water, and released the relevant information to the public, so as to facilitate the affected residents to get water; (4) as it is learnt that the WSD is implementing the Water Intelligent Network (WIN) project under which about 2 400 discrete District Metering Areas (DMAs) and associated Pressure Management Areas will be established within the fresh water distribution network in Hong Kong to monitor the situation of water loss, whether the WSD has established DMAs in Tsuen Wan and Kwai Tsing districts; if so, of the effectiveness of WIN in monitoring water main bursts in the two districts; if not, when the WSD expects to complete establishing DMAs in the two districts; (5) apart from WIN, whether the WSD has other methods in place to monitor the situation of fresh water loss, so as to give advance warning of potential water main burst incidents; if so, of the details; if not, the reasons for that; and (6) as it is learnt that in the past, a salt water main burst incident occurred in a Tenants Purchase Scheme estate in Kwai Tsing district, and since the water main involved did not serve to supply salt water to that estate but to a Home Ownership Scheme court nearby, the relevant Owners' Corporations of the estate/court concerned, the Housing Department and the WSD were unable to reach a consensus on the repair responsibility, of the new measures put in place by the Government to coordinate the repair works of water mains which are located within the precincts of a housing court but do not supply water to the residents of the housing court concerned, as well as clarify the responsibilities of various parties (in particular, to avoid the repair progress being slowed down by a lack of coordination among government departments)? Reply: President, The Water Supplies Department (WSD) strives to provide citizens with reliable and adequate supplies of high quality water and to this end, assures the health condition of the water mains networks by continuously improving asset management and making the best use of technology. After the WSD substantially completed the replacement and rehabilitation programme for approximately 3 000 kilometres of aged water mains (including fresh water and salt water mains) in 2015, the health condition of water mains networks has improved significantly. The WSD is currently implementing a risk-based water main asset management strategy to assess the risks of water main bursts and leaks and accord priorities to those with high risk for improvement works with a view to maintaining the health condition of the water mains networks and reducing the risk of water main bursts and leaks. Moreover, the WSD also establishes the Water Intelligent Network (WIN) to monitor water mains leakage and implements targeted measures for carrying out repair works in a timely manner. With these measures in place, the number of bursts in Government water main has dropped substantially from the peak of about 2 500 cases in 2000 to about 40 in 2022. The leakage rate (Note) of the Government fresh water mains has also decreased from more than 25 per cent in 2000 to 14.4 per cent in 2022. The replies to various parts of the Hon Chan's question are as follows: (1) and (2) On March 4, 2023, a section of fresh water main at Lei Shu Road, Kwai Chung, burst as a result of ageing. The WSD carried out emergency repair works immediately and completed the replacement of that section of water main the following day. According to records, the concerned water main was installed in the 80s of the last century and there had been no burst case involving it prior to the incident. In light of the incident, the WSD has included the fresh water mains in the vicinity in the mains replacement and rehabilitation programme with works commencing progressively within this year for reducing the risk of burst of nearby water mains. (3) To facilitate citizens' swifter access to temporary water supply during emergency water supply suspension incidents in future, the WSD has, in consultation with relevant estate management offices, established locations for emergency deployment of water wagons or water tanks at some of the large private and public housing estates in the Tsuen Wan and Kwai Tsing districts. Whenever a water suspension incident occurs, giving rise to the need for water wagons or water tanks to be put in position at the established locations, the WSD will inform the concerned residents through relevant estate management offices. (4) The WSD will establish about 2 400 District Metering Areas (DMAs) of the WIN within the fresh water distribution network in the territory. As at the end of March 2023, the WSD has established about 1 800 DMAs. Amongst a total of 280 DMAs to be established in Tsuen Wan and Kwai Tsing districts, about 240 DMAs have been commissioned. Some 40 DMAs remaining are under construction and are anticipated to be put into operation progressively by the first quarter of 2025. Establishment of the WIN aids identification of leakage areas and speedy repair of leaking water mains. Besides, we are further strengthening data analytics capability for more effective identification of leakage areas, speedy repair of leaking water mains and increasing the overall effectiveness of WIN. (5) As mentioned in the introductory paragraph, apart from the establishment of the WIN, the WSD has concurrently implemented the risk-based water main asset management strategy to assess the risk of water main bursts or leaks taking into account various factors, including the age and material of the water mains, past records of bursts or leaks, the impact of bursts or leaks, and the surrounding environment, etc, so as to formulate and implement the Risk-based Improvement Programme covering the replacement or rehabilitation of the water mains to minimise the risk of main bursts or leaks. (6) In general, the deed of mutual covenant (DMC) and land lease of each premises have already clearly defined the demarcation of responsibilities for the maintenance of the communal part of the inside service. Pursuant to the Waterworks Ordinance, the registered consumer or agent is responsible for the custody and maintenance of the inside service serving his/her own flat and communal service of the premises. If an individual consumer or agent encounters great difficulty in coordinating and arranging the required inside service repair works in an emergency situation, a request may be made to the WSD for assistance. In this connection, the concerned consumer or agent needs to bear the relevant cost of repair. It is believed that the case in Kwai Tsing district as mentioned is about the burst case in January 2021 of a salt water pipe of 150 mm diameter passing through Cheung Fat Estate for supply to the adjacent Ching Tai Court. In accordance with the related DMC and land lease, the owners of Cheung Fat Estate are responsible for repairing and maintaining the facilities within the estate premises, including the burst salt water pipe concerned. In respect of this case, the WSD, having considered the situation, carried out emergency repair and, in accordance with the Ordinance, demanded repayment of the repair cost from the relevant agent. Note: According to the Water Balance Method of the International Water Association, the Government fresh water mains leakage rate is the estimated proportion of real water loss against the system input quantity.