Authorities are facing an arduous task to restore water supplies to areas hit by last Monday's earthquake, an official has said.

Shao Yisheng, general secretary of the China Urban Water Association, said 7,800 km water pipes were damaged in the quake, although supplies in the worst-hit areas have been "basically" restored.

The association has called on its members across the country to dispatch professional repair teams to disaster areas, some of which have already arrived.

The Sichuan provincial construction department said 5,000 km of the damaged pipes served cities in the province. Also, 839 tanks and 1,281 water treatment works have been damaged, affecting 10.59 million people across the province.

The water supply to the 11 million people of Chengdu, the Sichuan capital, was largely unaffected, it said.

However, in medium-sized cities such as Dujiangyan, Mianzhu and Shifang, which are close to the quake's epicenter, supplies have been severely affected due to damaged equipment and contamination, the department said.