Skip to Content
This post may contain affiliate links. Please see our full disclosure policy for details.

How to Flush a Water Heater

Do you want to learn how to flush a water heater? Or, maybe you’re wondering “why flush out a water heater at all?” This is an important maintenance task because if a water heater is not flushed out periodically, it loses efficiency because of the excess build-up of sediment.

Sediment build-up slows down the transfer of heat by absorbing it. These sediments cause harm to the water heater (such as a water heater leak or create a clogged water line. The way to avoid this is to flush the water heater. 

 

How do I know if my water heater needs to be flushed?

If you are not sure if your water heater needs to be flushed, here are some clues that it may need it done: 

  • There is no hot water. If your water heater stops heating water, you either have a huge sediment build-up or a faulty burner. 
  • Weird odors are emitting from the water. This is a clue that bacteria is building up within the tank due to extreme sedimentation. 
  • The unit is starting to make odd noises. 
  • Hot water is coming out in the color of rust (this could mean your close to having water heater leaking from the bottom). 

 

What happens if you neglect to flush your water heater?

Your water heater might continue to produce hot water even though you fail to flush it.

When the heat increases from too much sediment build-up, you might notice steam bubbles. Also, excessive amounts of sediment in the tank can cause it to rattle around. When this happens, decrease the water pressure. Otherwise, it can cause the lower heating element to burn out.

The water heater is the appliance most ignore and take for granted. As long as it produces hot water, we hardly know it is there. It can function well for several years without upkeep. Yet, when it fails due to negligence, it can cause significant problems! 

No one wants to take a cold shower because the water heater is not functioning. Calling a licensed plumber is the best protection you can offer your water heating unit, as well as having it serviced once a year. 

The plumber will inspect the unit for any leaks and rust and verify that the thermostat and valves are functioning. To avert corrosion, sometimes the anode rod needs replacing, and finally, they will flush the water heater.  

You can save money by learning how to do the annual water heater flushing yourself. The object of this article will tell you how to do just that and protect your household investment. 

 

How long does it take to flush it?

How to flush a water heater

Once a year, for about 10-20 minutes, is all it takes to flush your water heater tank of sediments and mineral sediment. If you use a hose, you should continue running water through until it comes out clean. Regular flushing prevents sediment from building up. 

 

How often should I drain my water heater?

Flushing out water heaters advances the efficiency and life of the water heater unit. If not, the sediments will build up and calcify, resulting in the water heater not functioning correctly or failing completely.

It becomes an expensive issue if you wait too long because you will have to pay money to replace it. You should drain a water heater periodically to ensure optimum performance.

It is imperative to flush your water heater because of the minerals contained in water. Some areas have limestone underground, the water will gather deposits containing magnesium and calcium, resulting in hard water.  

This hard water becomes sediment and limescale that builds up and settles at the bottom of the heating unit. If you have a heater powered by natural gas, it creates uneven heat, which can make the tank leak. Electric water heaters have their own issues, causing the scaling to burn out. With both types of heaters, sediment builds up can clog the valves. 

 

How do you flush a water heater?

The first step in how to flush water heaters involves verifying the drain valve is not leaking at the water tank’s bottom. Turn off the water to do this. You will need to open the drain valve several times and close it. This is done in case there is any remaining sediment in the drain causing a blockage. Opening all faucets makes sure the water flows to prevent air trapping. You want to keep the heater turning on when water is drained.

You should see some water draining while alternating the valve from open to close as you do this. If this technique is not successful, you must shut the cold water supply off on the tank and call a professional. 

You will need to turn off the water supply prior to starting this project. In addition, if there is a water softener connecting the mainline and water line, this must also be shut off. 

Turning off the thermostat to the water heater is the next step. Should the heater turn on when the tank is empty, it can be damaged. If you have an electric water heater, you may need to turn off the circuit breaker.

 

The importance of turning off the main water supply

Turning down the water temperature to the water heater is an important step. If you have a water heater with a “vacation” mode, you should set it to that setting. The primary objective is to avert the heater from coming on after draining the water. This is particularly important if you have a natural gas heater because you can harm the tank if it heats up without water in it. Before moving on to the next step ensure to close off the valve that supplies gas. 

 

Connecting a Garden Hose to the drain valve

This step involves using a garden hose. First, you need to connect the end of the hose to the tank drain valve. Next, ensure to keep the drain valve open to allow the removal of sediment and mineral deposits. The opposite hose end should be pointed toward the floor drain or outdoors. Then open the drain valve to allow water draining to remove any sediment left.

Ensure the hose’s end is placed in the drain or a bucket to prevent your house from flooding.

Ensure that it flows in an area apart from your home. For example, keep the faucets for hot water opened until water starts to flow from them. Doing this averts the trapping of air in the pipes. 

Turn the cold water valve to mix the sediment remaining at the bottom of the tank. Any remaining scale or sediment plugs the drain valve.

 

How to flush a water heater

The first step is to turn the heating element to the off position. This allows the unit to cool down. Next, the water heater thermostat needs to be turned down or off. Ensure no one is taking a shower or doing laundry or dishes prior to turning off the heating element.

When draining old water from the hot water heater, don’t be shocked if you see rust and sediment coming out. It normally takes a couple of minutes for the water to become clear, and then you can then turn off the faucets. However, for extreme blockage you might need first to take off the temperature-pressure release valve to suck the water out with wet/dry vacuum.

This next step is about setting the thermostat for the water heater to a setting you prefer. For example, with a natural gas heater, you should reopen the gas supply valve and relight the pilot light. This is a process the manufacturer of your water heater recommends. In about 15 to 20 minutes after the tank is full there should be enough available water. 

The process also applies to tankless water heaters, as they are prone to mineral sediments’ harmful build-up.

 

Verify the faucets are open

Now you must verify you have hot water flowing. Allow the water to become clear first, because there may be sediments and rust coming out from the bottom of the tank. Shut off the hot water tap once you recognize the water is flowing steadily.

To keep a vacuum from developing, ensure a minimum of one hot water faucet is running. Permit the hose to empty the tank, while you are open the water heater’s drain valve. Release what’s left of pressure in the hot water pipes downstream.

A vacuum will retain any trapped liquid within the tank until you remove your finger. Next, open up the drainage valve to the water heater and allow it to continue to drain. Make sure you verify the water is flowing from the hose. Keep your eye on the amount of sediment flowing out as well. If you have pets or small children, ensure they stay away from the drainage valve. 

When you flush a water heater, there are different instructions for a gas water heater and an electric water heater. First, you need to open the hot water faucets throughout the house, so no air is trapped in the pipes. Leave these hot water faucets open until water begins to flow out clear.

 

Turn off the cold water supply

You can shut off the faucets once the water appears clear. Then set the thermostat to the water heater to your preferred setting. Finally, call a professional and turn the cold water supply off if you notice any water draining.  

Set your gas water heater to pilot or vacation mode if you have an older system. You might need to completely turn the water heater gas off prior to draining the heater. 

 

If you aren’t sure how to do it, calling a licensed plumber is the best bet. You can find a plumber in your area here.

 

Related: How Long Does it Take to Install a Water Heater?

This post may contain affiliate links which go towards keeping this site running. Please see our Disclaimer and Privacy Policy for more. We are a member in the Amazon Affiliate Program. Thank you for your support!