Selling hot water in power plants is to increase the water sales business on the basis of heating companies, and sell hot water to residents through the waste heat generated by heating.
Rebuilding the boiler in the original heating area is called secondary water supply, which has nothing to do with the original. Independent running tap water system is called direct drinking water station. These two methods are implemented only after approval by relevant local authorities, so the hot water sold is legal and compliant if it meets relevant regulations.