The top water authority has ordered companies to make public the results of their monitoring of drinking water quality, after a serious case of pollution affected the water supply in Shanxi and Hebei provinces.

The Ministry of Housing and Rural-Urban Development, in charge of water supply urged all water supply enterprises to set up a system to release information on water quality and be supervised by the public by the end of 2013, Xinhua News Agency reported.

Water supply enterprises need to have the capacity to examine all quality indicators, which increased from 36 to 106 since July 1, 2012.

Tons of aniline from a chemical plant in North China's Shanxi province leaked into the Zhuozhang River on Dec 31, affecting a downstream city in neighboring Hebei province. Handan, the affected city suspended its water supply on Saturday, but the water supply was gradually restored on Sunday after it switched its water source to groundwater.