Note: Leaking natural gas can be dangerous. If you smell natural gas (it smells a bit like garlic) near the water heater, shut off the pilot light, close the gas shutoff valve, and call a plumber or your gas utility company for assistance. See our information on gas leaks.
How to Flush & Drain a Water Heater
Before draining and flushing your water heater, turn off the gas or electric power (depending on whether it is a gas or electric water heater) and let the water cool a little. Close the incoming water valve and attach a hose to the drain valve to run the water into a large bucket or to a drain or the outdoors. Open the drain valve and open one hot water faucet somewhere in the house to let in air. When all water has drained from the water heater, turn the cold water valve on and off until the water from the drain runs clear. Then close the drain valve and the hot water faucet, open the cold water valve, and turn the water back on.
This is also a good time to test the temperature-pressure relief valve, which keeps pressure in the boiler from building up too much. Lift or lower its handle. Water should drain from the overflow pipe.
Water heater tips
Water heater problems normally become self-evident: A hot water faucet fails to summon hot water, you see dripping or puddles near the water heater, or the tank emits strange gurgling or popping sounds.