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Following is a question on the standard of drinking water in Hong Kong by Mr James TO Kun-sun and a written reply by the Secretary for Works, Mr Kwong Hon-sang, in the Legislative Council meeting today (Wednesday) :
Question¡G
At present, Hong Kong adopts the standards stipulated in the World Health Organisation Guidelines for Drinking Water Quality (1993) (WHO standards). It is reported that according to the recent territory-wide test on drinking water samples carried out by the Water Supplies Department, of the samples collected from public housing, the iron rust level of 8% of them exceeded the standard; of those from private housing, 18% exceeded the standard. In this connection, will the Government inform this Council:
(a) whether it knows the countries which adopt the WHO standards and the countries which adopt more stringent standards;
(b) whether it will, in conducting regular testing of the water quality of drinking water meets the standards, consider using domestic tap water instead of freshly treated drinking water from water treatment works; and
(c) whether it has plans to conduct comprehensive sample tests on the water quality of domestic tap water, and notify those households whose water samples have iron rust levels exceeding the WHO standard?
Reply¡G
Madam President,
(a) Singapore and New Zealand are some of the countries that adopt the Guidelines for Drinking-water quality recommended by World Health Organisation (WHO) (1993).
The attached table compares number of parameters under WHO's guideline values (GVs), United States Environmental Protection Agency's (USEPA) Maximum Contaminant Levels (MCLs) and European Communities' (EC) Parametric Values (PVs). It is difficult to say which standard is better than the other.
The WHO Guidelines are the consensus opinion of over 200 authoritative experts from some 40 countries based on worldwide scientific and medical information. There are 94 parameters in the WHO Guidelines and 68 in the US Standard, while the EC Standard has 26. It is noteworthy that there are 48 parameters for which WHO has set guideline values and the US did not set any, and 38 parameters for which WHO has set guideline values and the EC did not set any. We can only come to the conclusion that there can be no direct comparison between standards, and the USEPA and the EC Standards are not better than the WHO Guidelines in all respects.
(b) The quality of water supplied to the consumer is strictly controlled at all times through regular sampling from treatment works to connection points to ensure compliance with the stringent requirements of the WHO. There is also a water quality monitoring programme covering water samples taken at catchment intakes, pumping station receiving Dongjiang water, storage reservoirs, treatment works, service reservoirs and distribution systems as well as consumers' taps.
The quality of water drawn from consumers' taps may be affected in certain aspects by the condition of the internal plumbing owned by consumers. Our investigation on the 1,800 water quality complaints in 1998/99 revealed that almost all of these complaints arose from problems of internal plumbing, such as corroded piping and dirty water tanks.
(c) The existing water quality monitoring programme already covers the water at consumers' taps. In 1998/99, 15,888 treated water samples were taken from consumers' taps as part of the monitoring programme. If the iron levels in the tap water samples have exceeded the WHO guideline value, we will notify the consumers for necessary actions.
In addition, we have commissioned a consultancy study on the quality of potable water supply within residential buildings in Hong Kong. The conclusion drawn by the consultant is that the quality of potable water in residential buildings in Hong Kong is generally satisfactory. The problem of discoloured water is noted and it is mainly due to the rust from corroded inside plumbing, mostly unlined galvanized iron (GI) pipes. The use of unlined GI pipes in new buildings and in large scale renovation in existing buildings has been banned since December 1995.
End/Wednesday, June 9, 1999
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Table Comparing Chemical Parameters
of WHO GVs, USEPA MCLs and EC PVs
Comparison No. of Chemical Parameters
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WHO GV more stringent 25
than USEPA MCL
WHO GV exists for which 48
USEPA MCL not set
WHO GV same level 1
as USEPA MCL
WHO GV less stringent 20
than USEPA MCL
USEPA MCL exists for 19
which WHO GV not set
WHO GV more stringent 4
than EC PV
WHO GV exists for which 38
EC PV not set
WHO GV same level 10
as EC PV
WHO GV less stringent 42
than EC PV
EC PV exists for which 13
WHO GV not set
WHO GV = World Health Organisation Guideline Values
(1993)
USEPA MCL = United States Environmental Protection
Agency (1998) Maximum Contaminant Level
EC PV = European Communities Parametric Value (1998)