❄️ Are You Ready For Winter? CLICK HERE for our guide to winterizing your sprinkler system »
How To Flush A Water Heater - Plumb University

How To Flush A Water Heater

by Trevor Woods | Last Updated: August 18, 2020

Your home’s water heater is easy to take for granted. It sits out of sight and out of mind quietly warming your water over the years. And a water heater will continue to run for years without much maintenance required.

But, a neglected water heater might keep your hot water flowing for a long time however, its performance will slowly degrade and cause your utility bills to creep up. Sediment gathering inside your hot water tank can cause a number of other problems and greatly reduce a water heater’s lifespan.

Luckily draining and flushing your water heater is an easy way to keep it performing the way it should!

Why Should I Drain My Water Heater?

Believe it or not, all tap water has some degree of minerals in it. In some areas where there is a lot limestone, chalk, or gypsum deposits beneath the soil the water can pick up these minerals and become quite “hard”. Hard water creates sediment in the form of lime and calcium scale as the minerals settle out of the water.

In electric water heaters, this buildup can stick to heating elements and inhibit the elements’ ability to warm water. This reduces the water heater’s efficiency as well as shortens the life span of the now harder working elements.

Gas-powered heaters with sediment buildup will have uneven and less efficient heating. You can sometimes hear a gas water heater with a lot of buildup on the bottom as it rumbles and rattles during a heating cycle. Noisy water heaters are a result of the hot water bubbling up through the sediment on the bottom of the tank.

And if enough sediment accumulates on the bottom of either electric or gas water heaters the drain valve can become clogged. This means your water heater can’t be readily serviced and can result in water heater failure, yikes!

You spent good money on your water heater and you can protect your investment by periodically draining and flushing your water heater. This maintenance will help rid the tank of sediment buildup and increase its efficiency and lifespan.

How Often Should I Flush My Water Heater?

Most homeowners should flush their water heater annually as part of their routine maintenance plan. But depending on the quality of your water you may have to drain your hot water tank more frequently.

You may have to flush your water heater twice a year or once every few months if you have extremely hard water. Having your water heater serviced this often can really add up so learning how to drain your hot water tank can save you a lot of money over time.

You can gauge how often you need to flush your hot water tank based on the amount of sediment you catch when you follow our step by step instructions below.

Tools And Materials Needed

No specialized plumbing tools are required to complete this water heater maintenance. You will need:

Flexzilla Garden Hose
$18.47

Extremely flexible and durable!

All-weather flexibility makes it easy to maneuver around tree, bushes, and other obstacles. Flexible hybrid polymer material allows the hose to lay flat with no memory. Durable and abrasion-resistant outer cover and crush resistant anodized aircraft aluminum fittings.

Buy Now
We earn a commission if you click this link and make a purchase at no additional cost to you.
02/17/2024 04:28 pm GMT

How To

1. Turn Your Water Heater OFF

Before you start draining your tank, you need to turn the water heater off so you don’t accidentally do any damage to the unit. You can turn electric water heaters OFF at the power supply located at your home’s circuit breaker panel.

Gas water heaters can be shut off at the gas control valve or by turning OFF the gas supply.

2. Attach The Garden Hose

Next, you’ll want to attach a length of garden hose to the drain valve located at the bottom of the hot water tank. Run the other end of the hose to the nearest floor drain or somewhere safe outside.

If you’re letting the water drain outside, make sure it’s far enough from your foundation so it doesn’t flow back into your home or the crawl space. Also, it’s a good idea not to drain your water heater into flowerbeds, gardens, or shrubs. The hot water can damage seeds and kill your plants, whoops!

Stain And See The Sediment

Slide a paint strainer or a pair of knee-high stockings over the end of the garden hose. Then secure it in place with a rubber band or twist tie. This will collect all the sediment you drain from your water heater so you can check to see if you’re on the right maintenance schedule.

Pack Of 25 Paint Strainers
$1,999.99

High quality, fine mesh filters.

These filters are made of a durable nylon mesh that won't rip or tear easily. Designed to filter out particles that are larger than 200 microns makes them perfect for a variety of applications including paint, beer brewing, and protecting plants from pests.

Buy Now
We earn a commission if you click this link and make a purchase at no additional cost to you.
02/17/2024 06:07 pm GMT

3. Turn OFF The Water

Now you can CLOSE the cold water inlet valve to the water heater. If you can’t locate the shut-off valve, you may have to turn OFF the main water valve to your home.

Then open a faucet somewhere in the house to relieve the system pressure inside the hot water tank. This will allow the water to easily pour out of the water heater and prevent creating a flow-stopping vacuum.

4. OPEN the Drain Valve

Now OPEN the drain valve with a flat blade screwdriver. Remember to be careful if you are near the end of the garden hose as the water draining from the tank will be hot! This water can exceed temperatures of 125°F and can scald or cause severe burns instantly.

Continue to drain the water heater and monitor the end of the garden hose. Keep checking for a steady flow of water and make sure the hose does not get clogged with sediment or debris.

Increase Your Flushing Efficiency

OPEN and CLOSE the water supply valve several times if you really want to blast out the sediment inside your water heater. The increased water pressure will stir up and flush out any lingering debris or sediment. The water will flow quickly, so be ready for it at the end of the garden hose!

5. CLOSE the Drain Valve

You will typically only need to drain 3 to 5 gallons of water to do a proper flush of your water heater. There is no need to completely drain the hot water tank.

Once enough water has been flushed from your hot water tank you can turn OFF the water heater’s drain valve. When the water stops flowing from the garden hose, it can be disconnected from the drain valve.

6. Turn ON The Water

It’s time to turn the water back ON to the water heater. Start by opening a hot water faucet somewhere in your home. This will allow the air trapped inside the tank a place to exit as it refills with water.

OPEN the cold water inlet valve or your main water valve and you’ll hear the water heater start to fill up, whoosh!

The faucet you opened will cough and sneeze as it expels all the air from inside the water heater. Once you have a steady stream of water flowing from the faucet, it can be turned OFF.

7. Turn Your Water Heater Back ON

Once the water heater is full of water again you can turn the water heater ON. Switch the electrical power back ON at the circuit breaker for electric water heaters and turn the gas supply back ON for gas-powered models.

You may need to relight your pilot as per the instructions on your hot water tank or follow our guide here.

Allow your water heater an hour or so to heat back up. It’s a good idea to recheck the drain valve one more time to make sure it’s tightly closed. Tighten the drain valve as necessary. Done!

https://www.youtube.com/watch?v=TCFCwldQHAs

Preventative Maintenance

It’s a good idea to flush your heater regularly. I keep an old garden hose attached to the drain valve rolled up and ready to go to speed up my water heater flushing.

We recommend that you flush your water heater annually but you may need to do it more often based on how hard the water is where you live.

You can judge how often you need to flush your hot water tank based on the sediment you remove. If you use a paint strainer on the end of your drain hose you can monitor your sediment buildup.

When you flush your water heater and you have about a cup of sediment, increase the number of times per year you flush the hot water tank. If you only notice a tablespoon of sediment, you’re on the right schedule!

How Do I Drain My Tankless Water Heater?

Excellent question, the above maintenance guide is for conventional tank water heaters only. Tankless water heaters are susceptible to mineral and sediment buildup but require an entirely different process to properly clean tankless heat exchangers.

Flushing a tankless water heater requires a pump to circulate a descaling solution through the system. You can purchase descaling kits that will come with detailed instructions to properly clean your tankless water heater.

Tankless Water Heater Flushing Kit
$159.99

Perfect for maintaining any tankless-style water heater!

This tankless water-heater cleaning kit includes everything you need to fully maintain your water-heating system. And it comes with step-by-step instructions that are easy to follow.

Buy Now
We earn a commission if you click this link and make a purchase at no additional cost to you.
12/18/2023 09:51 am GMT

Conclusion

Flushing your water heater and discovering the schedule that keeps your hot water tank happy and healthy is easy! If you are new to an area you can always ask a neighbour about the local water quality or contact your water provider for information on how hard the water is.

Being able to flush your own water heater will save you money on your utility bill and prevent costly repairs or premature replacement. Flush on!

Happy Plumbing!

Trevor Woods is the founder of Plumb University® and he started in the plumbing and construction industry in 1997. Since then, his mission is to make plumbing repair and maintenance easy for everyone. And each year, he continues to help more people with their plumbing installation, care, and troubleshooting.