Independent tests show higher levels of lead in water supply at Hong Kong public housing estates
Expert report to commission of inquiry, based on different testing method from that used by government, says problem was worse than first thought
The extent of lead contamination in the city’s drinking water is significantly greater and more widespread than previously suggested, according to an expert report submitted to a government-appointed commission of inquiry into the scandal.
This is because testing was conducted using fully flushed water samples instead of first-draw ones, the report states.
The findings also reveal lead-tainted tap water was found in 11 samples at five more public housing estates previously labelled as “unaffected” by the contamination scandal.
These are the Shui Chuen O, Yee Ming, Choi Tak, Tin Ching and Kwai Chung estates.
Yesterday, Democratic Party legislator Helena Wong Pik-wan accused the government of deliberately playing down the contamination levels by using the fully flushed samples.
“I demand the government provide remedial measures for residents in these five estates including the supply of water tanks, water filters and blood tests to ease residents’ worries,” she said.
The report was prepared by Professor Joseph Lee Hun-wei of Hong Kong University of Science and Technology who conducted independent sampling in December on first-draw tap water samples from 43 buildings in 11 “affected estates” and six “unaffected”.
“[The government’s sampling method] does not reflect the actual and sometimes high lead concentrations to which the residents are exposed,” said the chair professor of HKUST’s department of civil and environmental engineering.
Straight-from-the-tap testing was carried out to compare with the government’s method of using fully flushed water samples.
The government had earlier taken samples after running the tap for at least two minutes. The test confirmed that the drinking water at 11 estates exceeded the World Health Organisation’s guidelines of less than 10 micrograms of lead per litre.
Independent sampling revealed 47.2 per cent of the “first- draw” samples had excess lead compared with 8 per cent of the fully flushed samples using the government’s method.
The report to the commission of inquiry also identified 25 buildings, most of them in affected estates, as “significantly lead-contaminated” with a “building concentration” greater than the WHO standard.
Lee, however, admitted lead concentration in most cases drop rapidly within 30 to 60 seconds. “A flushing time in the order of 0.5 to 1 minute appears to be adequate for guarding against risks of lead contamination,” he said.
The Housing Authority stated in response that it would examine the report findings in detail.
It explained that the Housing Department and Water Supplies Department, which conducted water sampling tests in public housing estates, suspected that some samples might have been contaminated and they would be discarded if they were found to have been affected by environmental factors.
In the case of Shui Chuen O Estate, which was among the five extra estates with lead-tainted water, the government said there was initially no contaminated water, as samples taken from three blocks did not exceed the limit, even though one taken from a vacant unit was found to have an excessive level of 14 micrograms per litre. That sample was discarded as officials concluded it had been affected by environmental factors.
The authority also said that samples would be discarded if the fresh water supply systems inside flats had been installed by the tenants themselves.
The authority said it would continue follow-up work in the 11 estates found with excessive lead.
