Selling water is permissible. Hence, there is no problem as per Shari’ah, for the companies who distribute filtered water and those who purchase water from water suppliers to distribute and sell water as a business as long as all legal requirements are fulfilled. However, it is not permissible for one to illegally attach his own pipe line to the government’s water pipes (from which water is directed to people's homes) and sell it to others. This must be avoided.
And Allah knows best.
