I had to replace our home’s rental water heater around the 14 year mark – which is within range of its lifespan – after the bottom of the unit rotted out, gave way and started leaking on the floor of our basement, next to the drain fortunately.
I never knew that you should flush a water heater so I never did it and I suspect the previous owner of the home didn’t either.
Your home water heater can be emptied and rinsed with relative ease and it’s a job you can do yourself with a garden hose. Flushing a water heater at least once per year removes sediment from the tank and extend its lifespan while also improving its energy efficiency.
How to flush a water heater
Draining A Water Heater Steps
While the video below shows how to flush a water heater visually, here are the main steps involved so you can see ahead of time if it’s something you want to do yourself.
Turn off the cold water supply to the water heater. This is typically a ball valve on the top of the water heater tank.
Turn down the water heater thermostat. Check the pic above and look at the white round knob. If you have a propane or natural gas heater, you probably have a Holiday or Pilot mode that you can turn it down to. If you have an electric heater like I do, you can unplug it. I also turn down the knob to the lowest setting to be safe. If you turn the pilot light off, you’ll have to relight it afterwards.
Connect a hose to the water drain valve. Just like in the picture above. I have a floor drain right at the bottom of my water heater which is convenient as I can literally empty the tank into the drain. You might need to extend the drain out of your house depending on the circumstances.
Open the water heater drain valve. If you look at the picture above just above where the hose attaches to the valve, you’ll notice a brass fitting that can be turned to open the valve to drain water from the tank. NOTE: Remember the water coming from the tank will be very hot and can burn. You might consider waiting overnight or at least several hours for the water to cool down before draining it.
Open at least one hot water tap in your house. By opening the valve it lets air into the system and will enable water to exit the tank faster. As the water is exiting the tank, check to see how much sediment is coming out. It’s possible that the sediment may or may not drain on its own. Your water heater also has a pressure relief valve that can be opened to further let air into the tank. Watch the video below to see how this is done as it’s important to close it again if you open it.
Open the cold water valve again. Once the tank is empty (this could take 20 minutes depending on water tank size and how quickly it drains) open the cold water valve on the top of the water heater. This will flush the system out and remove sediment that has settled and needs a bit of forced water to push it out. Keep an eye on the water leaving the tank and once it runs clear with no sediment, you can be sure that it is clean. If needed fill a clean glass or jar with some drained water and take a close look for signs of sediment. You might need to keep the valve open for 15-20 seconds or longer until the sediment has run out completely.
Finish the process. Once the water runs clear shut off the drain valve by the hose. Then disconnect the hose. As the water tank is refilling, take a look at the hot water faucet that you opened and leave it open until the air has run out of the system. Some dirty water might exit the faucet.
Reset the water temperature. Turn the water temperature back to the normal setting and/or plug the water heater back again.
Draining A Water Heater Video
Flushing a water heater is one of those tasks that is better shown visually than simply discussed in words. The video below shows how to flush the water heater from beginning to end including discussing some of the features and parts of the unit such as the water drain valve and safety pressure release.
How often to flush a water heater
Depending on how hard the water is in your local area, you might need to flush your water heater once every 6 months or once per year.
Flushing your water heater once per year will help to clean out sediment that has accumulated since the last time you flushed it and can help to extend the heater’s life. It also ensures that the heater can perform properly as sediment can impair the energy efficiency of the heater.
All water has at least some mineral content and hard water has a particularly high calcium and magnesium content. When water is heated, there is some evaporation and sediment falls to the bottom of the tank and settles there. Over time it will accumulate randomly which can cause uneven heating of the water in the tank which may lead to leaks and the lower heating element inside the tank burning out.
If in doubt, check with your water heater supplier especially if it’s a rental unit to see what they recommend. If you own your water heater, take a water sample to a local water filter company and get them to run a test on the hardness of your water. The harder your water, the more frequently you may need to flush your water tank.
If you don’t have a water softener, it’s possible your water will be hard regardless.
What happens when you don’t flush your water tank?
The harder your water is, the more sediment you are likely to accumulate at the bottom of your water heater.
The more sediment that accumulates in your water tank the:
- Less hot water can be heated since sediment at the bottom reduces the total displacement of the tank.
- Less efficient your water heater works and the more energy it consumes.
- Greater the risk of unevenly heated water.
- Sooner your water heater may need to be replaced.
Check out the video below to see how much sediment can accumulate on a water tank that has (likely) never been flushed. You may be surprised at the amount of debris that builds up over time.
How do I know if my water heater has sediment?
Look for several symptoms and clues that suggest you might have sediment at the bottom of your water heater than needs flushing.
You’ve never flushed your water heater. If your water heater is over 2 years old and has never been flushed, it’s likely you have sediment built up.
Your hot water emits smells and is rusty. If your hot water has a bad smell, is discolored or you see sediment coming out, it’s most likely a water heater that needs to be cleaned. Check the faucet aerator filters on each tap to see if they have sediment built up and rinse them out.
Hot water isn’t hot. If your hot water isn’t as hot as what it used to be, it’s likely a problem emanating from sediment in your water heater. If the sediment is particularly bad it can cover the heating element like the picture at the very top of this article. This can negatively affect its ability to heat the water and reduce energy efficiency too.
Noises coming from the water heater
Your water heater may make a number of noises that you don’t recognize. Here are some common sounds to be aware of.
Clicking: A gas-fired water heater will occasionally make a single clicking sound when the heater is igniting which is normal.
Ticking: A ticking sound typically comes from the heat trap and is not something to worry about.
Popping: A popping noise indicates mineral and sediment deposits at the bottom of the tank that need to be flushed.
Hissing: In all likelihood the water temperature is set too high. The hissing sound is a result of extra pressure exiting from the safety release valve.
Screeching: A screeching sound typically indicates that the cold water valve is only partially open and restricting water flow into the tank.
Crackling: A crackling sound in a gas water heater – similar to when you put a wet pot on a heated stove element – may be water condensation on the burner and doesn’t require you to do anything.
Pipes: Pipes that are loose and aren’t securely fastened to the wall can vibrate especially as cold and hot water passes through the pipes. Locate where the sound is the loudest and ensure the pipes are fastened correctly. They may require spacers added to lock the pipes securely.