I travel to China at least 6 times a year. But like stated above all tap water in any hotel not just in china but asia is not drinkable. You won't contact any diseases so brushing your teeth is fine just its not drinking qaulity. Everyone will boil water first before consumption.

From a personal point of view i would never drink tap water even in Australia or the US although bottled water could be just tap water in the US for all i know lol