China's environmental watchdog wants more household sewage treatment plants built and upgraded to improve water quality.

Such treatment plants are not being built quickly enough to satisfy the demands of growing cities, said State Environmental Protection Administration official Liu Youbin Wednesday.

Therefore, the administration has called on local governments to adopt more realistic pricing for household sewage treatment services.

According to Liu, although there is a great demand for sewage treatment facilities, investors are still daunted by the gap between operational costs and scanty returns mainly due to the unreasonably low charges set for household sewage treatment, a legacy of the old planned economy.

"They (investors) are not blind to the fact that many of the country's sewage treatment plants are partly, if not completely, inactive because of the lack of funds to operate them," said Liu.

He said more economically advanced areas should charge for household sewerage treatment at market rates, raising prices to attract more investment into the field with a proper profit margin.

In special cases, private operators can also build and operate sewage networks for profit.

But in comparatively backward areas, the government should play a major role, gradually increasing household sewage treatment fees as local residents earn more.

By the end of 2001, China had 452 household sewage treatment plants, treating 36.5 per cent of the country's total sewage water, 17 per cent more than in 1995.

A total of 520 household sewage treatment plants will need to be constructed by the end of 2005, but so far work has begun on only 186 of them.