How to Flush a Water Heater

Flushing a water heater involves draining sediment buildup from the tank through the drain valve at the bottom, which improves efficiency and extends the unit's lifespan.

1. Kill the Power First. Shut off electricity at the breaker for electric units or turn the gas control to pilot for gas units. Close the cold water supply valve at the top of the tank. This prevents new water from entering while you work.
2. Route the Runoff. Attach a garden hose to the drain valve at the bottom of the tank. Run the other end to a floor drain, outside area, or large bucket. Make sure the hose slopes downward so water flows freely.
3. Let Air In. Turn on hot water taps throughout your home, starting with the highest faucet and working down. This allows air into the system and helps water drain faster from the tank.
4. Drain the Tank. Open the drain valve fully using pliers if needed. Water will start flowing out along with sediment. The first water out will be dirty and may contain chunks of mineral buildup.
5. Stir and Clear. Once the tank empties, turn the cold water supply back on briefly. This will stir up remaining sediment. Let it run until the water coming out of the hose runs clear, then shut off the water supply again.
6. Restore and Restart. Close the drain valve and remove the hose. Turn on the cold water supply and let the tank fill completely. Close all hot water faucets once water flows steadily from them. Restore power or relight the pilot light.