It can be used as a water storage tank, but it is best not to use the water stored in the solar water heater for drinking.
The pipes of the water tank and the water system of the solar water heater are not designed according to drinking water standards. Drinking quality tap water will be subject to secondary pollution to varying degrees after being stored in the solar water heater. tank for a while, so it is not potable and can be used for other purposes in life.