Water Heater - DO NOT use if the tank or fixtures have been submerged in floodwater!
(1) Turn off the gas or electricity to water heater (turn off electricity at the fuse or breaker box, turn off gas by locating the valve supplying the hot water heater and turning the valve handle so that it crosses – is not lined up with – the gas line)
(2) Turn off the water intake valve (should be located near the water heater)
(3) Open the drain at the bottom of the tank
(4) Turn on a hot water faucet (water will drain from the tank, not the faucet)

Discard the first few gallons if they contain rust of sediment. Do not turn the gas or electricity back on until the tank is refilled.

Pipes
(1) Turn off main water valve where the water comes into the house (usually near the water meter if you have city water).
(2) Let air into the pipes by turning on the highest faucet in your house.
(3) Get water from the lowest faucet in your house (never get water from faucets that have been submerged in floodwater).

Ice - If you have freezer space, consider freezing part of your water supply. This has the added advantage of keeping food in the freezer cold longer during a power outage.
 

Learn how to provide a safe supply of drinking water for your household in a disaster.