Beijing Waterworks Group, the capital's biggest supplier of tap water, said that the city's water quality meets the required standards and does not contain excessive heavy metals, Beijing Times reported Tuesday.

A man surnamed Qian said that his plumber tested the water in his home last week using a water detector and the results showed a level of heavy metals that was four times the accepted level. Qian told the group, which sent one of its own staff to test the water and found that it did meet the required standards.

The company also said Qian's water detector detects minerals, not heavy metals, and tests for heavy metals must be carried out by technicians.

It added that the group has a strictly scientific method to processing the water and maintaining the purity of the water source.

The technicians also said that some water purifier companies give the impression their products can measure water quality in a bid to increase sales.