How to Flush Your Water Heater


As water runs through your water heater, it leaves behind minerals that can build up in the tank, reducing your water heater’s efficiency. It creates a layer of sediment that makes heating the water in your tank difficult. This sediment can also clog your water lines if it isn’t cleared. You can avoid these problems and increase the life of your water heater by periodically flushing the tank. It’s a great idea to go ahead and check it at least once per year and flush the tank as needed. You know you need a flush if you release water from the spigot at the bottom of the tank and it comes out a milky color, full of sediment.

annual water heater flush

These instructions are designed to help the do-it-yourself homeowner take care of their own water heater. However, if you read the following instructions and feel like this might be a bigger job than you want to take on, call a plumber you trust to help.

Complete the following 4 steps FIRST before performing ANY maintenance on your water heater to avoid the risk of water damage, scalding burns, electrocution, or explosion:

  1. Disconnect power at the breaker for an electric water heater.  
  2. Shut off the gas valve for a gas water heater and make sure the pilot light is extinguished.
  3. Close the cold water inlet valve or main water supply. 
  4. Turn on the hot water at a faucet somewhere in the house. No water will come out of the faucet; this simply helps to relieve the pressure inside the water heater tank. 

To flush the tank, connect a garden hose to your spigot and make sure it leads to a drain. Be aware that the water coming out of the tank will likely be VERY hot and should not come into contact with people, pets, or plants. Open the spigot and let the water run.* If possible, turn the water off and stir up the sediment on the tank's bottom by briefly opening the cold-water supply valve. Drain and repeat until clean water comes out of the hose. You may want to empty the water into a large pan or bucket so you can accurately tell when there is clear water coming out of the hose. 

*Pro Tip: Most plumbers do NOT recommend completely draining your tank. Not only does it waste a lot of water, but reintroducing cold water back into a hot, empty tank could shatter the glass liner or otherwise compromise the structural integrity of the tank.

   red arrow For step-by-step instructions on how to flush your water heater, click here.


AFTER performing any water heater maintenance, you MUST remember these steps:

  1. Close the tank spigot, and disconnect the hose from the spigot. Next, close the pressure relief valve. Turn on a hot-water faucet in the house to regulate pressure. Finally, turn on the cold-water inlet and refill the tank.

  2. As water begins to flow from the hot-water faucet, you can turn it off.
  3. Tips for igniting the pilot light or turning the electricity back on: 
    • Gas Water Heaters - Making sure the gas valve is in the “on” position, set the control knob to “pilot.” Press the knob and then push the igniter button. You should see either a blinking light indicating the pilot light is lit or a small flame through the viewing window. The first time you light the pilot light, you may notice a lot of condensation. This is normal, and as the water temperature stabilizes, the condensation should go away. (Be sure to thoroughly read your user’s manual for detailed instructions on the manufacturer’s recommendations for lighting the pilot light on your particular water heater model.)
    • Electric Water Heaters - If you have an electric water heater, DO NOT TURN ON THE ELECTRICITY BEFORE THE WATER TANK IS FULL. If the heating elements in your water heater tank are not fully immersed in water, they could burn out if turned on. A burned out heating element will result in no hot water and will have to be replaced. So, before you restore power to the water heater, begin filling the tank and then turn on a hot-water faucet somewhere in the house and let the water run for about 3 minutes. This helps relieve the air pressure in the tank until it is completely full of water. When the tank is full, flip the breaker to turn the power back on. If you don't have hot water after two hours, check to make sure the unit is getting the correct voltage. Power information can be accessed by consulting the label on your water heater. No electricity or the wrong voltage can cause many problems with electric water heaters. If you feel like this might be the case with your water heater, call a licensed electrician to help you with your power or wiring problems.
    • Electric Water Heaters, continued - If you find that you have a burned-out heating element in your electric water heater, you’ll need to disconnect power to the water heater at the breaker panel and again drain the water heater. Once drained, go inside and disconnect the wires from the element and, using a wrench, loosen the element. Once it’s loosened, unscrew the element and pull it out. Replace with the new element and tighten it down with a wrench. Reconnect the wires and fill the tank, following the instructions above.

  4. Be sure the temperature on the water heater is set to 120F.

If at any time you feel overwhelmed, have questions or concerns, call a plumber you trust for help. If you don’t have a trusted, licensed plumber and are in the Utah market, call Any Hour Services and we’d be happy to send a plumber to your home to assess your system, perform any maintenance for you, and answer any questions you might have.

If water heater maintenance sounds overwhelming or like one more thing you don’t have time to do yourself, call Any Hour Services and we’ll have one of our licensed plumbers perform your annual water heater maintenance for you!

What if keeping track of your water heater’s annual maintenance seems overwhelming? That’s okay! Some of our customers will actually choose to enroll in our Comfort Assurance Plan (CAP) so they don’t have to remember these annual maintenance inspections at all. As part of your CAP membership, we will call and remind you and then come and do the tune-up and system check. As part of your plan, you can even add other systems to your CAP plan and have a licensed HVAC technician check and inspect your system or a licensed and certified electrician come and do an annual electrical inspection. Call if you have any questions about our CAP maintenance program.



Author: Amber Smith-Johnson
Copyright © 2019 by Any Hour Services


Aug 8th 2019

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