LCQ11: Water mains bursts

Following is a question by the Hon Lau Kong-wah and a written reply by the Secretary for Development, Mrs Carrie Lam, in the Legislative Council today (October 31):


Will the Government inform this Council:

(a) of the respective monthly average numbers of incidents, in the past two years, in which fresh water and salt water supplies were suspended because of pipe burst; the public housing estates ("PHEs") particularly affected by such incidents and the reasons for that;

(b) whether it will take measures to alleviate the inconvenience caused by suspension of fresh water or salt water supply to residents of individual PHEs estates which are particularly affected; and

(c) of the latest progress of the comprehensive Replacement and Rehabilitation Programme of Water Mains being implemented in phases by the Water Supplies Department?


Madam President,

(a) In respect of water mains managed and maintained by the Water Supplies Department (WSD), there were on average 111 incidents of water mains bursts per month in the past two years resulting in temporary suspension of water supply.  Of these incidents, 50 and 61 cases involved fresh and salt water mains respectively.

Some of the water mains bursts affected public housing estates.  The estates more frequently affected, in terms of the average number of cases per year, were Tai Wo Hau Estate in Tsuen Wan (3.5 cases), Lower Wong Tai Sin Estate in Kowloon (2.5 cases), Lek Yuen Estate in Sha Tin (2.5 cases), Shun Lee Estate together with the adjacent Shun On and Shun Tin Estates in Sau Mau Ping (1.5 cases), and Shek Lei Estate in Kwai Chung (1.5 cases).  The majority (about 75%) of these incidents resulted in disruption of salt water supply, while the remaining 25% involved fresh water supply suspension.

WSD will continue emergency repair works on fresh water mains burst into the night if necessary to ensure early resumption of water supply.  Records show that fresh water supply was resumed within 6.8 hours on average.  With regard to salt water supply, the emergency repair works will usually be suspended during the night, to avoid noise nuisance to neighbouring residents.  As a result, it takes a longer time to resume salt water supply.

Aging of water pipes is the main cause of the bursts.  The problem could be accentuated by external factors such as heavy vehicles on the road and adjacent trench works.

(b) Staff of WSD and staff of Housing Department's estate management office work closely in the emergency response to water mains bursts.  Temporary water supply points are established using facilities such as water tankers and water tanks, for use of the affected estate residents.  Staff of the estate management office would also keep residents informed of details of the temporary water supply and progress of water mains repair works.

After resumption of water supply, WSD would assess the need for quick improvement to the water mains network through minor works, to reduce potential mains burst nuisance.  These may include, for example, replacing individual sections of the worst-aged water mains to reduce the likelihood of further mains burst, or install valves at appropriate locations of the pipelines to facilitate isolation of bursts to reduce the area of suspension of water supply.

(c) WSD is implementing a four-stage programme to replace and rehabilitate 3,000 km of aged water mains throughout the territory.

Works for the first two stages of the programme have commenced, and the rest will start in 2008 and 2011 respectively.  To date, works have been completed on about 370 km of water mains, and are in progress on about 980 km of water mains.  The lengths of water mains under design and planning are 800 km and 850 km respectively.  It is estimated that all works will complete in 2015.

Ends/Wednesday, October 31, 2007
Issued at HKT 14:30