Water Heater Maintenance - Flushing the Tank

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How to flush your hot water heater to improve efficiency and prolong the life of the unit.

Unless you have an indirect or tankless hot water heater, periodic flushing is recommended by all water heater manufacturers. How often it should be done depends on the quality of the water supplied to your home. Domestic water supplies that have high mineral content be flushed more often.

Why you should flush your Hot Water Heater?

Your heater will accumulate sediment consisting of very fine sand and various mineral deposits. If left alone the resulting buildup of sediment can compact as it settles at the bottom of the tank reducing the efficiency of the heater, creates popping noises in gas fired units, and can become so deep that the sediment covers the lower heating element on electric hot water heaters.

Hot water heater sediment


You will need a bucket, garden hose (preferably one that is good for hot water, a flat head screwdriver (some drain valves don't have handle but ibstead have a slotted to prevent accidental opening) and a pair of pliers.

1. Turn off the heater. If you have a gas hot water heater, set the gas valve to "Pilot" to prevent the burners from coming on while you are flushing it. If your heater is electric be sure to turn off the circuit breakers.

Note: If the water level drops below the electric heating elements and the thermostat turns the elements on, the heating elements will crack and burn out.

2. Connect a garden hose to the drain valve at the bottom of the tank. Make sure the outlet of the hose is going to a floor drain or into a large 5 gallon bucket. Since the water will be very hot you should use a pair pliers to tighten the hose onto the drain valve.

3. Close the shut off valve on the cold water supply at the top of the water heater.

4. Carefully open the temperature/pressure relief (TPR) valve at the top of the tank by lifting the lever. Leave the valve open to prevent a vacuum from forming inside the tank. You can also open up a hot water faucet on a sink.

5. Open the drain valve at the bottom of the heater allowing the water to flow out through the garden hose.

a. If the sediment is clogging the drain valve then try closing the TPR valve or hot water faucet and turn the cold inlet valve back on to force the sediment out.

b. With tanks that have not been flushed previously the sediment may have hardened into chunks that can block the drain valve. The tank must be drained completely, then you can remove the garden hose and use a stiff wire or long screwdriver break to break up the clog.

6. When the water runs clear shut off the drain valve and remove the hose.

7. Close the pressure relief valve at the top of the tank and turn the cold inlet valve back on.

8. Open a hot faucet in your house, and let it run until no air comes out.

9. Turn the heater back on with the gas supply control valve or circuit breakers.

Flushing your water heater may only take 15 minutes, but it could take an hour if there is heavy sediment accumulation inside the tank. Either way, flushing the hot water heater will prolong the life of your unit, improve the quality of the hot water, and save you on your utility costs. It may also prevent a catastrophic failure that can flood your home.


Roberta Baxter
Posted on Aug 11, 2011
Francina Marie Parks
Posted on Aug 9, 2011