Water heaters should be flushed at least every 1 to 3 years, depending on make and models, to help control the build-up of mineral deposits. Flushing will help the water heater operate more efficiently and usually extend its life. It's a good idea to flush the water heater if 1) the water becomes a yellow or brownish color from an accumulation of rust; 2) you notice sand-like mineral sediments; or 3) calcium build-up causes white flaky particles in the fixtures.
1. Turn off the electricity or gas to the water heater.
2. Shut off the cold water inlet to the tank.
3. Attach a garden hose to the tank drain valve located near the bottom of the tank. The drain valve usually looks like a regular garden faucet or a round dial with a threaded hole in the middle.
4. Extend the garden hose to a place where the water can safely exit the heater.
5. Open the pressure relief valve or turn on a faucet in the house to allow air in the tank.
6. Open the drain valve to allow the water to exit the tank. Caution: water leaving the heater will be hot and under normal household water pressure.
7. After five minutes of flushing, fill a bucket with the still flushing water.
8. Allow the water in the bucket to stand for a minute. See if the water is clear or if any sand-like material settles to the bottom. If the water is clear, go to step 9. If the water is discolored or you see sand-like material at the bottom of the bucket, repeat steps 6 and 7 until the flushed water is completely clear and free of sediment.
9. Close the drain valve and remove garden hose. Turn off inside the faucet and close pressure relief valve. Turn on the cold water inlet.
10. Don't forget to turn on the gas and electric power to the tank.If you are not comfortable flushing the hot water heater, another option is to hire a licensed plumber.