Beijing's water supply company said on Monday that the city's tap water quality is the best among Chinese mainland cities and safe enough to drink, following a media report that some residents in the capital do not drink tap water for the sake of their health.

The Beijing Waterworks Group cited several indices that show on the city's tap water meets national standards, the Beijing News reported.

The announcement came after a report by Southern Weekly that a Beijing couple, both water quality experts, has used filtered or bottled water for 20 years and only drink mineral water. They even use filtered water to wash their floors.

The couple said their personal choice doesn't mean tap water is not safe, adding that they do it to maintain their health.

The waterworks group confirmed to the Global Times Tuesday that it will post quarterly water quality reports on its official website starting January 15. It also said the piping system is strictly supervised with 243 monitoring stations, which will increase to 302 this month.

Despite the continued reassurances, few residents drink water straight out of the tap. Many families order 20-liter jugs of water that are delivered to their door. Others at least boil water before consuming it.

Chen Zhu, a resident in Tongzhou district, said he gives his 3-year daughter only bottled water, because of sediment he has seen in tap water. "I believe what I see."

The national standard on drinking water, which took effect in 2007, regulates sediment, nitrates and 104 other indices affecting quality.

However, a report by caixin.com showed that by May 2012, only half of more than 4,000 water suppliers in the country were producing drinking water at the national standard.

Ma Jun, chief of the Institute of Public and Environmental Affairs, told the Global Times that increasing pollution in water sources was partially to blame. "Water quality is determined by three major factors, the source, the water supplier and the pipeline system. In China, many cities are having trouble with polluted sources of water," Ma said.

Ma said one of Beijing's biggest water issues is a diminishing supply, as major reservoirs had less capacity or were abandoned due to pollution, and ground water supplies have been overexploited.

Beijing is expected to receive additional supplies of water in 2014, when the middle section of the South-to-North Water Diversion Project is scheduled to begin pumping water from Hubei Province.