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How To Flush Or Drain A Water Heater

It’s important to flush or drain a water heater tank periodically to so the water heater will heat efficiently and produce ample hot water. Save money and time by handling this project yourself. Plan to do it once every two years.

Why is it so important? Because of mineral deposits collect at the base of a water heater tank, these deposits can build up to a very thick, crusty coating. This coating diminishes the transfer of heat from the burner to the water in the tank. With a lapse of time, it additionally causes corrosion. Also, deposits can break free, clogging faucets, pipes, and the valve that is used to flush or empty the water heater tank.

Most water heaters employ a large, insulated holding tank to ensure there’s plenty of hot water on hand at all times for different purposes throughout the home. Over time, naturally occurring minerals in the water, as well as sand and grit flushed from municipal water lines, can settle in the bottom of the tank. This sediment build-up can potentially reduce the efficiency and capacity of your water heater. It can also plug the drain and interfere with ongoing maintenance, leading to early failure.

Simple Ways To Take Into Account:
1. Turn off electricity and water to the water heater; allow heater to cool.
2. Drain water from the heater's tank using a garden hose and pump.
3. Catch drained water in a bucket for inspection.
4. If water is filled with sediment, refill heater and drain again.
5. Continue to fill and drain heater as often as necessary until the water runs clear.
6. Disconnect the hose and pump.
7. Turn on the electricity and water to the water heater.

Let’s Take Deeper Doing It Step-by-Step:

Step 1. If you have an electric water heater, turn the electrical power to the water heater off at the breaker box. If you have a gas water heater, turn the thermostat to the vacation mode setting or the lowest setting possible without actually turning off the pilot light.

Step 2. Allow the water heater to cool. This can be done by waiting for the heater to cool down for a few hours or someone could take a shower, do laundry, or wash some dishes at this time causing all the hot water to be used up (after, all you already paid to heat it!) and replaced by cold water.

Step 3. Turn the cold water supply to the water heater off - this valve is normally located at the top of the water heater on the INLET side.

Garden hose connected to hot water heater
Step 4. Connect a garden hose to the drain outlet valve at the bottom of the water heater but do not open the drain valve just yet. Place the other end of the garden hose in a convenient drain location or someplace outside like onto your lawn or garden area. Note that the hose outlet must remain lower than the water level in the tank in order for the water to drain completely out of the water heater.

If you choose to not wait for the water heater to cool, then make sure you use a hose that can withstand hot water. The other end of the hose should be placed where hot water will not harm anything, like children, pets, plants or shrubs, and remember the hose and hose outlet may be too hot to handle with your bare hands.

You can also use a water heater drain pump to speed up the process. Depending on which water heater drain pump you use you can empty a 50 gallon water heater tank within 2-1/2 to 10 minutes instead of waiting for the water heater to drain by gravity.

Step 5. Open the hot water side of your kitchen faucet (or the hot side of any faucet close to your water heater). This will allow air to flow back to the water heater stopping any vacuum in the water heater that will keep the water from flowing out of the drain.

Step 6. Now go back to the water heater drain valve and open it slowly until it is fully open. If you are using a water heater drain pump, turn the pump on after you have opened the drain valve. As the water flows out of the water heater you can let it drain into a clean bucket to see how much sediment is being flushed out. This can help you determine how often you may (or may not) need to flush your system, and also whether or not you might want to consider installing a filtering system.

Turn off cold water supply
Step 7. Once the water heater is drained, turn the pump off, if using a pump, and close the drain valve. Open the cold water supply at the top of the water heater and let the water run for 5 to 10 minutes. This can help to dislodge more sediment that may still be in the bottom of the water heater.

Step 8. Turn off the cold water supply at the top of the water heater and again open the drain valve (turn the pump on again if pump is used) and let this water drain out of the tank. Examine the drain water to see if there is still sediment in the drain water or if it is clear. If the water still has some sediment in it then repeat Steps 7 and 8 until the drain water runs clear of any debris.

Step 9. Once you are sure all of the sediment has been drained from the tank then turn off the pump, close the drain valve and remove the garden hose.

Step 10. Now, while the tank is empty, may be a good time to check your Anode Rod and your T&P valve. We suggest you replace the Anode rod if the water heater is over 5-years old. We also suggest you remove and inspect the T&P valve for possible corrosion from certain water conditions and replace it if necessary. If you have a gas water heater you may also want to check the gas vent at this time.

Step 11. When you are ready to refill the water heater, open the cold water supply at the top of the water heater and begin to fill the water heater tank. Check to make sure the drain is closed and does not leak. If the drain valve leaks it could have sediment debris caught inside of it. Turn off the cold water supply at the top of the water heater and clean the debris out of the drain valve. Re-open the cold water supply at the top of the water heater to fill the water heater.

NOTE: If the drain valve is not functioning properly it may also need to be replaced. You can normally use a regular 3/4" fipt inlet hose bibb with a short pipe nipple. The length of the pipe nipple will depend how much insulation is used between the water heater tank and the cosmetic exteror cover. Remove the existing drain valve to determine the length of nipple needed to clear the cosmetic cover.

Step 12. As the water heater fills up, go back to the faucet used in Step 5 to let air into the water heater and let the hot side run until water runs freely through the faucet without releasing air with the water. Turn on a few more faucets (hot side) in the house and let them run until water runs freely there too. If you have a two story house then be sure to open a faucet in an upstairs room as well.

Step 13. Once you are positive all the air has been purged from the water lines and the water heater, you can again start to heat up the water. If your water heater is electric, simply turn the electricity back on to the water heater. If your water heater is natural gas or propane, just turn the thermostat back up to your desired temperature setting.


Flushing a water heater is more of a maintenance item that a repair. It can be a repair for a electric hot water tank. Sediment can burn out the elements.

Ten minutes to set it up, fifteen tops and another fifteen to clean up. That was all the work involved. You were probably able to do other things while the water was flushing out the tank. This won't be so bad, less than and hour once a year. Congratulations for completing your hot water heater flush.