LCQ19 : Measures to reduce water mains bursts

Following is a question by the Hon TAM Yiu-chung and a written reply by the Secretary for Works, Mr Lee Shing-see, at the Legislative Council meeting today (June 26) :


In view of the several cases of burst potable water mains and salt water mains recently, will the Government inform this Council of:

(a) the number of cases of burst water mains, and the respective numbers of them which resulted in disruption of water supply and traffic congestion, in each of the past three years;

(b) (i) the total length of underground water mains replaced by the Water Supplies Department ("WSD") for preventing pipe-burst; and

(ii) to prevent road excavation works from endangering the water mains nearby, the respective numbers of times WSD issued instructions and warnings to the contractors concerned before the works commenced and during the progress of the works, in each of the past three years; and

(c) the specific measures, apart from the proposed plan to replace and repair aged water mains of about 3 050 km in length by phases within 20 years, to prevent the pipe-burst problem from getting worse?


Madam President,

(a) In the past three years, there were a total of 5 618 cases of burst water mains, among which 4 825 cases resulted in interruption of water supply to the affected premises, and 1 519 cases led to traffic congestion. The number of cases by financial year is as follows:

1999/00 2000/01 2001/02 Total
Burst Cases 1,813 1,924 1,881 5,618
Cases Resulting in Interruption of Water Supply 1,577 1,652 1,596 4,825
Cases Leading to Traffic Congestion 462 484 573 1,519

(b) (i) To prevent main bursts, the Water Supplies Department (WSD) replaced 77, 66 and 83 kilometres of aged water mains in the 1999/00, 2000/01 and 2001/02 financial years respectively.

(ii) To prevent road excavation works from endangering the water mains nearby, WSD has published and distributed the booklet-Guidelines for Excavation near Water Mains, which explains in detail the points to note when undertaking such works. The Guidelines are also available on the WSD website for reference by contractors, organizations concerned and the public. In fact, before the works commence, the contractors or utility undertakers will generally approach the WSD for the latest information on the existing water mains near the site of the proposed works. Apart from providing the required information, WSD will repeatedly remind them to implement suitable precautionary measures before carrying out the works. In the 1999/00, 2000/01 and 2001/02 financial years, WSD issued 891, 782 and 700 warnings respectively to the contractors concerned during the progress of the works.

(c) In addition to the long-term Water Main Rehabilitation Scheme, WSD has put in place the following measures to reduce the number of main bursts:

(i) Using stronger and better quality pipe materials, such as ductile iron pipes, mild steel pipes and polyethylene pipes to replace the cast iron pipes, asbestos cement pipes, galvanized iron pipes and uPVC pipes in new water main works.

(ii) Setting up Roadwork Inspection Teams to step up the surveillance of roadwork activities which may affect water mains, and giving advice to the contractors on the proper protection of water mains. Warnings will be issued if necessary.

(iii) Undertaking territory-wide leak detection tests regularly to identify leaks in water mains at an early stage so as to prevent them from developing into bursts.

(iv) Enhancing the knowledge and awareness of contractors and all parties concerned, including government departments, large organization, utility undertakers and consultants, on the importance of avoiding damage to water mains by issuing to them various publicity materials.

(v) Converting existing water mains record plans to digital format and making full use of the computerised mapping system to facilitate the updating of and access to information, as well as information exchange with other utility undertakers and government departments.

End/Wednesday, June 26, 2002