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The Task Force on Investigation of Excessive Lead Content in Drinking Water today (October 31) submitted its final investigation report to the Secretary for Development, Mr Paul Chan. It concluded that excess lead in drinking water in Kai Ching Estate and Kwai Luen Estate Phase 2 was caused by the use of leaded solder materials in the solder joints. Copper alloy fittings also leached lead but did not result in excess lead in drinking water.
"We agree to the findings of the report and will actively study and follow up on the recommendations. We are very grateful to the Task Force for its hard work over the past three months and its professional advice on the measures to prevent recurrence of similar incidents in future," Mr Chan said.
During the investigation, the Task Force dismantled more than 100 components of pipes and fittings from the three water supply chains in Kai Ching Estate and Kwai Luen Estate Phase 2 and conducted leaching tests, elemental analyses, lead isotopic analysis and mathematical modeling. In coming to the above conclusion, it also made comparison with the actual situation at Hung Hei House at Hung Fuk Estate in Yuen Long which uses stainless steel pipe that does not require solder jointing. Lead content in the water samples collected from the water supply chain of Hung Hei House was found to comply with the World Health Organization's provisional guideline value. The results were suitable for comparison.
The Task Force also examined the inside service of nine other public rental housing development projects with excess lead in water samples. It was found that the design of the inside service and the specifications of the pipes and fittings in these projects were similar to those of Kai Ching Estate and Kwai Luen Estate Phase 2. Leaded solder materials were also used in the solder joints. The Task Force considered that the cause of excess lead in drinking water in Kai Ching Estate and Kwai Luen Estate Phase 2 should be applicable to these nine housing projects.
Separately, the Task Force noted that there was leaching of nickel in some taps dismantled from the two water supply chains of Kai Ching Estate, but it could be flushed away within one to two seconds after turning on the taps. The amounts of chromium and cadmium leached from all the components were very low.
The Task Force also found that the brands and models of some valves and taps among the pipes and fittings dismantled from the three water supply chains in Kai Ching Estate and Kwai Luen Estate Phase 2 were not those submitted to the Water Authority before the commencement of construction of the inside service (although they were on the Water Authority's directory list of pipes and fittings). Some of the copper alloy valves and taps did not comply with the British Standard (BS) requirements in respect of lead content, but the leaching test results of these copper alloy valves and taps were comparable to those complying with the requirements. In other words, these valves and taps would not result in excess lead in drinking water.
The Task Force considered that the excess lead in drinking water incidents reflected inadequate awareness of the stakeholders in the construction industry on the use of leaded solder materials and its consequences on drinking water quality. To prevent recurrence of such incidents, the Task Force made a number of recommendations to prevent use of leaded solder materials and non-conforming pipes and fittings, and recommended the Water Authority to explore the use of pipe materials free from the risk of misuse of leaded solder joints in plumbing works, and to review relevant legislation. It also recommended the Housing Authority to consider requiring the adoption of central procurement for solder materials.
Regarding the case of Legionnaires' Disease in Mun Ching House at Kai Ching Estate reported on May 28, the Task Force followed up on the progress of disinfection work in Mun Ching House carried out by the working group of the Housing Department. It noted that the water samples taken after disinfection of the entire water supply system of Mun Ching House tested negative for Legionella pneumophila, and therefore considered that no further follow-up action was required.
The full report is available on the Development Bureau's website (www.devb.gov.hk/filemanager/en/Content_3/TF_Final_Report.pdf).
Ends/Saturday, October 31, 2015
Issued at HKT 14:30
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