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How To Drain A Clogged Water Heater

draining a hot water heater

How to drain a clogged hot water heater is not difficult to do when you follow these steps. If your drain valve is completely open but you still only have a small dribble of water coming out it’s usually because of sediment build up in the bottom of your tank.

Over time, especially if not flushed on a regular basis, mineral deposits accumulate in the bottom of the tank which is a combination of calcium, lime scale, and iron that are present in the water. If you’ve waited too long to flush it out the sediment blocks the drain plug.

Sometimes, if your hot water heater has reached its lifespan (8 -10 years on average), it may have so much sediment inside and so corroded to the point it needs to be replaced. Replacing a hot water heater can be very costly so here’s a simple solution that you can try that won’t cost you anything.

It’s a good idea to flush your hot water heater at least twice a year depending on your hard water to help it operate more efficiently and increase the lifespan of tank.

How to clean the inside of a hot water heater

Items needed

  • Flathead screwdriver or channel locks
  • Water hose
  • Garden hose quick connect
  • Electrical wire
Step 1

Make sure you turn off the cold water supply to the hot water heater at the main water valve. If the unit is refilling it will take forever to drain. You don’t want any water flowing back into the hot water heater.

Step 2

If you have a gas heater turn the gas to the pilot setting and for an electric hot water heater turn off the corresponding circuit breaker.

Step 3

Open up the hot water faucet closest to the hot water heater so that the air can circulate through the pipes. The unit may be draining slow due to the low air pressure inside the tank.

Step 4

Grab your garden hose and use a quick connect (see below). These couplings are the perfect answer to threading and unthreading hoses and hose attachments. They just snap in and they’re ready to go. Put the quick connect on the valve, tighten it and snap on the garden hose.

garden hose quick connect

Step 5

Open your drain port with the flathead screwdriver or the channel locks depending on what type of water heater you have. The hose needs to be placed in some type of landscape or sink.

Please keep in mind that hot water is coming from your heater so keep your children and pets away so no one gets burned. The process to completely drain the hot water heater should take 20 -30 minutes.

Step 6

If the hot water heater is not draining or the water is not flowing out freely you’ve got a clogged drain. One thing you can try is to see if you can shoot water back into the tank by stepping on the garden hose a few feet away to see if this will loosen the clog.

You can also try to unclog the heater with a wire (see video below) but be careful that you have given the water time to cool before trying the method shown below.

If this still doesn’t work then close the valve and contact a plumbing professional or handyman to flush the tank for you.

Step 7.

Close off the drain port and turn the water supply back on. Open the cold water valve so water can flow back into the tank.

Step 8.

Turn off the faucet that you opened that is closest to the hot water heater. At first, the faucet will be filled only with air but as soon as you see a stream of water flowing out then you can turn it off.

Step 9

If you have a gas heater you can now turn the thermostat back to the on position. If you have an electric heater you will need to turn the breaker switch back on.


If you talk to 10 different plumbing professionals you will get ten different answers on how often you should perform a hot water heater sediment flush. We recommend doing a flush twice a year but at the very least do it annually to maintain the highest efficiency and to help extend the life of your heater.

You’ll know that you need to flush more often if when you flush you see that there’s a lot of sediment buildup in your water.

Be extremely careful when you are doing the heater sediment flush yourself because the water is scalding hot and can cause serious burns.

We hope this article has given you enough information on how to drain a clogged water heater.


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