So said the Beijing Youth Daily newspaper recently.

Statistics show Beijing has more than 40,000 of the wells, which provide 2.5 billion cubic metres of water, or three quarters, of the capital's annual water supply.

The rest of the city's water comes from water companies.

Most of the wells are located in the suburbs rather than the city centre. Legal individually-dug wells are those built by industrial enterprises and some rural areas sponsored by local governments. Originally the water from the wells was mainly used for irrigation and industrial purposes. But later on, with no official approval, local residents began to drink the water.

The capital city's efforts to control the water supply from the wells came after some illegal wells posed a potential threat to public health.

They account for about half of the individually-dug wells in the city, starting up with no legal approval and avoiding annual water-testing fees.

Recently, hundreds of local people were affected by drinking water from illegally-built wells.

"With the completion of the South-to-North Water Diversion Project in 2008, the city will gradually close the wells down," Dai Yuhua, the director of water resources management at the Beijing Water Affairs Bureau told China Daily.

Last month more than 50 residents in Tongzhou District were hospitalized after drinking unsafe water.

On August 31 more than 500 people in Haidian District vomited and had fevers after drinking polluted water from the community well.

In order to search for illegal wells, health departments in Beijing have been using GPS systems and local authorities have also conducted surprise inspections.

Meanwhile, to solve rural residents' drinking water shortage, the Beijing Tap Water Company has been extending its water pipelines.