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Why do you need to flush your water heater? Your water heater is one of those “out of sight, out of mind” appliances you count on every day. It’s a workhorse and can run for years without a problem, but once it quits, you’re looking at quite a large cost to replace it. 

But even if it does keep performing its behind-the-scenes duties, unless your water heater is periodically maintained, it could be literally draining your money as it begins to run less efficiently. 

One reason why your water heater may start to perform poorly is because calcium and magnesium deposits – also known as limescale – accumulate and build up in the tank. Flushing your water heater can remove those deposits before they can cause damage, and make the appliance more energy-efficient. When you periodically flush your water heater, you can extend the life of this expensive appliance and also save on your monthly water bills.

How Often Should You Flush Your Water Heater?

A licensed plumber can flush your water heater during your annual service call – and you should definitely plan to have your water heater inspected every year to replace the anode rod (which prevents corrosion), to check for leaks and rust, and to ensure that the thermostat and valves are in good shape. 

But it may be necessary to flush the water heater more than once a year. You may need to do it once every six months, or as often as every few months if your local water supply contains a lot of mineral content.

If you don’t flush your water heater at least once a year, water pressure can drop, mineral buildup will begin to clog toilets and faucets, and the water tank will start to deteriorate. 

How to Flush Your Water Heater

The good news is that it’s relatively simple to flush your water heater on your own. See the easy-to-follow instructions below for a conventional tank water heater:

    1. Turn off electricity or gas: If the heater is electric-powered, at the main breaker panel, turn off the circuit breaker to disconnect power. If gas, turn the control knob to the “pilot” position.
  • Turn off water supply: Manually close the cold water supply valve to the water heater. 


  • Turn off the water heater thermostat: You shut this off to avoid having the heater turn on when all of the water drains out. That could damage the tank.


    1. Connect a garden hose: The hose should connect to the drain valve, which is at the bottom of the water heater. The other hose end should either flow into a drain or outside of the house far enough away from the foundation or any plantings.
  • Turn on the hot water at a nearby faucet: This prevents a vacuum from forming and will allow the water to drain more easily.
    1. Open the water heater’s drain valve: You may need to use the flathead screwdriver to loosen it. Now, the draining process should begin. However, if you don’t see any water coming out, the valve could be clogged by sediment. If that’s the case, first open the temperature pressure release to drain any water in the pipes before you use a wet/dry vac to suck out the sediment blockage enough for the water to start flowing. Let the water flow out completely.
  • Turn on the cold water supply: This begins the flushing process and will get rid of any sediment in the bottom of the tank. Let the cold water run until the output at the end of the hose looks clear. Turn off the cold water supply.
    1. Disconnect the hose from the drain valve: Use the wet/dry vac to clear any remaining sediment away from the valve. Then close and tighten the valve. Once the valve is closed, turn the cold water supply back on.
    2. Hot water faucets remain on until there’s not rust or sediment flowing: Once clear, you can turn off the faucets.
  • Turn on the power source for your water heater: Follow the manufacturer’s directions and make sure you fill the tank with water before turning on the gas or electrical connections.

Cooper Plumbing Provides Expert Services in Houston, Texas

The technicians at Cooper Plumbing are all licensed and certified plumbers, and we invest in their training so that their knowledge and skills are kept up-to-date. We know that any kind of plumbing issue can be stressful, so you can count on our expert staff to treat you with the respect and professionalism you deserve while we provide the excellent service and workmanship you expect. Contact us to request service or call 832-441-9683.