How to Clean Water Heaters in 4 Simple Steps

Christine Herrington

Christine is our Chief Editor and a contributing writer to the site.

Last Updated on May 8, 2021

Among all the home appliances people maintain, the water heater is often overlooked. It’s recommended that you clean your water heater at least once every year to get rid of debris and mineral deposits that can slowly accumulate inside.

Cleaning a water heater helps it run smoothly and makes it a lot more durable. Even though it might sound complicated, cleaning a water heater is simple, and it can be done in less than 30 minutes

To clean a traditional water heater, it’s important to be systematic and follow a series of simple steps to keep it in perfect condition. 

How to Clean Water Heaters in 4 Simple Steps
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Table of Contents

How Does a Water Heater Work?

A traditional water heater stores hot water that is used and then refilled. Underneath the tank, there’s a heating element that warms up water as it comes through the bottom. As the water heats up, it rises to the top of the tank due to the reduced molecular density, where another pipe takes it to your faucet or shower when you need it. 

Some people today have what is called a tankless water heater. A tankless water heater creates hot water on demand instead of continuously storing it throughout the day. The tankless water heater system is more complicated, which makes it difficult to clean. 

Why it’s Important to Clean a Water Heater

Like any other piece of machinery, your water heater also needs some maintenance. It’s recommended to clean a water heater once a year, but every two years will also be fine. 

The main reason for cleaning a water tank is that minerals such as calcium and magnesium settle and stick to the bottom and sides over time. This is a particularly pernicious problem in areas that experience hard water. When the sediment buildup becomes too big, people start experiencing different problems, such as:

  • Loss of heating power.
  • Sudden changes in water temperature.
  • Heater becomes energy inefficient, resulting in rising utility bills. 
  • Cloudy water from the faucet.
  • Possible health issues for those using the water. 


If you haven’t cleaned your tank in more than five years, it’s recommended that you be careful when draining it. The problem is, over many years, sediments that accumulate at the tank’s bottom create hotspots. When these are overheated, the steel can start to break down, creating a tiny hole. If you suddenly scrub off all the sediment by draining and flushing, that hole can cause a small leakage. 

How to Clean a Traditional Water Heater

Cleaning a traditional water heater isn’t difficult. There are only four basic steps you’ll need to follow, and you won’t need any special tools except for a long brush, a hose, and a wrench. 

Step 1: Turn off the water heater 

The first thing you need to do is turn off the water heater. Everything should be turned off without any water coming in or leaving the tank. The three things you’ll need to turn off are the thermostat, the gas or electricity connected to the heater, and the cold water supply. 

The thermostat is located near the bottom of the water heater. Some people set it on pilot mode, but it’s better to turn it off completely. The gas pipe is connected to the thermostat. In the case of an electric water heater, the power has to be turned off with the switch in the breaker box. Finally, you’ll find the valve for the cold water supply near the top of the heater. 

Step 2: Drain all the water out

This step is fairly simple. The old water has to be drained out of the tank in order to clean the interior. To avoid a vacuum effect in the pipes when draining water out, open a hot water faucet in the house and leave it on during the whole process

Usually, near the thermostat, you’ll find a small metal valve with a tube connecting to the tank. This is the tank’s drainage point. Connect a garden hose, and before turning on the valve, make sure the hose leads all the way outside or into a large bucket. 

When you turn on the drainage valve, the water that starts coming out of the hose will be brownish. This is because of the sediment inside the tank. Keep the spigot open until the water runs clear. Once the tank is completely drained, remove the garden hose.

Step 3: Cleaning the tank

For this step, you’ll need a long narrow brush. This step of how to clean water tanks takes a bit of hard scrubbing. It’s possible to use the same brush that is used to clean refrigerator coils. You’ll also need a wrench to remove the drainage valve.

If the drain valve is made of plastic, you can use this time to change it for a more durable one, such as a new brass valve. Once you have removed the drain valve, use the long brush to clean the bottom of the tank and the sides as much as possible. The idea is to break loose all the buildup that is stuck on the tank’s sides. 

Do not put the drain valve back on yet; there’s one more important step to take. 

Step 4: Flush the tank

For this step of how to clean water tanks, you’ll need one more simple tool. A drain valve is unsuitable for flushing because it gets easily clogged. For flushing, use a ¾” plumbing nipple. Screw it on the drainage opening and connect the garden hose to it once again. Also, make sure the other end of the hose is outside the house or in a bucket. 

Turn on the cold water valve on top of the heater and let the water run until it becomes clear. Finally, repeat the process of draining, scrubbing and flushing until there is no more sediment, and remember to turn off the hot water faucet that was running the whole time. 

Enjoy Clean, Hot Water in Your Home

Cleaning a tankless water heater is a bit different than cleaning a traditional one. For this type of water heater, people usually use a submersible water pump. This is because, unlike a traditional tank, you don’t have large volumes of water to help you remove the sediments. There are also tankless water heaters cleaning kits which include all that’s needed. 

In general, learning how to clean water heaters is easy and the process doesn’t involve a lot of extra materials. For just 30 minutes every year, it’s a great time investment to maintain the efficiency of the tank and improve its durability. 

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