Also, shut off the valves on any water lines leaving the house, such as an outside faucet. Water in the hot water tank or a pressure tank represents many gallons of safe water for use in an emergency. If there is advance warning of the emergency, assure the freshest water supply by flushing the tank. Turn off the gas or electricity to the hot water tank, so that there is no risk that the heating unit could come on while the tank is being emptied. Draw water as needed from the drain valve at the bottom of the tank.
Water stored in the plumbing system is safe for only a limited time.
Most experts agree that this water will stay safe for only a few days. After a longer time, it must be disinfected before it is used for drinking or cooking. Depending on what has happened, you may need to flush or decontaminate your plumbing system before returning it to normal use. Storing Water Water can be stored for short-term use in clean, sanitized containers with covers or lids. If there is advance warning of an emergency, clean large pots, pans, and jugs with hot water and dish detergent.