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Water quality of Sheung Chui Court within limit
     In view of media reports on the lead content found in drinking water in a unit in Sheung Chui Court, the Hong Kong Housing Authority (HA) said last Friday (July 14) that the HA would, upon seeking the owner's consent and with the Water Supplies Department (WSD)'s technical support, flush the water pipes thoroughly to reduce the amount of residual metals in the drinking water, conduct water sampling test after flushing, and announce the results when available.
     The government has sought the consent of the owner of the unit concerned at Sheung Chui Court and flushed the water pipes of the unit concerned thoroughly. Use of water was then suspended until a water sample was taken for testing the following day. The lead content of the water sample was within the World Health Organization's limit, which showed that the pipes in the unit had been thoroughly flushed, a Government spokesman said today (July 21).
     Since the "excess-lead-in-water" incident in 2015, the Government has taken various measures to enhance the regulatory control on the construction of inside service to ensure the safety of drinking water, the Government spokesman noted. The HA has also strengthened the monitoring of contractors and sub-contractors as well as the control and checking of materials, including soldering materials, through measures ranging from contract specifications, delivery and verification of materials, monitoring during construction to testing upon completion. According to the Waterworks Ordinance, inside service materials and fittings of all newly completed buildings, including Sheung Chui Court, must be submitted to the Water Authority (WA) for approval prior to the commencement of works. Upon completion of installation of Sheung Chui Court's inside service, the contractor conducted water sampling tests as required by the WSD, including tests on lead content. The test results were within limit. During inspection of the inside service, representatives of the WA also carried out lead content inspection for the solder joints. The results were also within limit. A completion certificate for the completed works was issued by the WSD in March 2017 to approve water supply.
     The WSD pointed out that there will generally be minute amount of lead leaching from new copper alloy fittings (e.g. taps and valves) during the early stage of use. This is a normal phenomenon and will only last for a short period of time. Under normal daily use, the minute amount of leached metal will be carried away quickly and the leaching of lead from the copper alloy fittings will reduce rapidly to a very low level after a week to a few months. 
     The Expert Committee on Plumbing Materials of the WSD pointed out that, "In order to improve the machinability and lubricity of alloys such as brass and bronze for the manufacturing of copper alloy fittings with different shapes, a small amount of lead will be added to the copper alloys by manufacturers. Casting or assembling of copper alloy fittings usually involve grinding process, during which the lead containing particles at the surface of the copper alloy will be loosened. Therefore, the lead containing particles at the surface of the new fittings will leach into water easily during the early stage of their use. Over time, the lead containing particles on the copper alloy surface will be gradually leached away. Together with the protective oxide layer gradually formed on the surface of the copper alloys, the leaching of lead from the copper alloy fittings will reduce rapidly to a very low level after a week to a few months. Under the situation of normal daily use, the lead leached from the fittings is not likely to accumulate in the pipework of the plumbing system."
     To further reduce the leaching of metals from new pipes and fittings, the WSD last year engaged a scholar of a local university to conduct a study and established a systematic flushing protocol to cleanse newly installed inside service to speed up the rate of reduction of leaching of metals from new pipes and fittings. The protocol is proved to be effective for reducing the leaching of metals (including lead) from new pipe and fittings through laboratory tests and field trials at new buildings (including private and public buildings). To rapidly reduce the leaching of metals of new plumbing systems, the WSD issued a circular letter in June 2017, requiring contractors and licensed plumbers to cleanse the new inside service according to the protocol before it is put into use.
     Nevertheless, if the water in the plumbing system has not been used for a long time, leached metals and other substances may accumulate in the stagnant water. Therefore, the WSD has always encouraged consumers to run the water taps for two or more minutes before taking water for cooking and drinking if the plumbing system has not been used for a long period of time. This will wash away the accumulated metals or other substances before water consumption. The flushed water can be stored and used for other purposes. Thorough flushing should also be carried out in existing premises where new pipes and fittings are installed.

     As testing of metal contents in water samples involves measuring trace chemicals in water samples, stringent sampling procedures and testing protocols shall be followed otherwise any contamination by the surrounding environment may affect the test result. Extra care should be taken during sample collection for such purpose to avoid the test results from being affected by contaminant in the surrounding environment.
Ends/Friday, July 21, 2017
Issued at HKT 20:03
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