Water Heater Flush – How To Do It Safely & Easily

Water Heater Flush - How To Do It Safely & Easily

Anthony Barnes

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Water heaters are essential appliances in every home. They provide hot water for showers and baths, laundry, cooking, and drinking.

If your water heater isn’t working properly, however, it can cause serious problems.

Flushing your water heater regularly helps prevent mineral buildup inside the tank and keeps the sediment from entering your pipes. This prevents clogs and other issues that can damage your plumbing system.

In this article, we will show you how to flush a water heater safely and easily. You’ll learn about the different types of flushes available, what they do, and when to use them.

We’ll also explain why regular flushes are important, as well as some tips on how to carry out a proper flush.

How To Flush Your Water Heater: The Basics

There are two main ways to flush a water heater. One is by using a chemical-based solution, which uses chemicals to dissolve any minerals or sediments that have built up over time.

The other way is with an electric current.

The first method requires a special chemical called a “water softener.” These products contain sodium hydroxide (NaOH), which dissolves calcium carbonate deposits.

This process removes the calcium and magnesium ions from the water, making it softer and more suitable for bathing.

The second method involves running electricity through the water heater. This causes the metal components inside the tank to become heated.

As the water heats up, the minerals and sediments float to the top of the tank, where they fall into a drainpipe.

Both methods work equally well, but there are pros and cons to each one. Let’s take a look at both options.

Chemical Method


  • Chemical flushes are safe, easy, and inexpensive.


  • Some people find the smell of these solutions unpleasant.
  • Chemicals may be toxic if used improperly.

Electric Method


  • No chemicals required.
  • There is no odor associated with this type of flush.


  • Electric flushes require professional installation.
  • The cost of installing an electric flush can be high.

Why Should I Flush My Water Heater?

Why Should I Flush My Water Heater

A water heater should be flushed periodically to keep it clean and operating efficiently. Over time, minerals and sediments build up inside the tank.

When this happens, the minerals and sediment particles block the flow of water through the heating elements.

This reduces the efficiency of the unit, and eventually leads to a complete failure of the heater.

In addition, the buildup of minerals and sediments can lead to corrosion of the internal parts of the heater. Corrosion weakens the structure of the tank, causing leaks and cracks.

If you don’t flush your water heater regularly, then you could face major problems down the road. For example, if you notice rusting around the bottom of the tank, this could indicate a leak.

If you see any signs of corrosion, then you need to call in a plumber immediately.

How Often Should I Flush My Hot Water Heater?

It depends on the size of your hot water heater. If you have a small tank, then you only need to flush it once every year or so. However, if you have a large tank, then you might want to flush it once every six months.

You can check the manufacturer’s instructions to determine how often you should flush your water heater.

Flushing Your Water Heater Before Winter

In most cases, you will want to flush your water heater before winter. This helps prevent mineral deposits from building up during the cold weather.

During the winter, when temperatures drop below 50 degrees Fahrenheit, the amount of calcium and magnesium ions in the water increases.

This makes the water harder than normal, which means that it won’t heat as effectively.

As a result, you will use more energy to heat the same volume of water. You also run the risk of having to replace your heater sooner than expected.

Flushing Your Water Heaters After Summer

After summer, you should flush your water heaters again. During the warm season, the amount of calcium in the water decreases. This allows the water to heat up quickly.

However, after the summer, the temperature of the water drops back down.

At this point, the amount of calcium ions in the water is higher than usual. This makes the water hard, which slows down the heating process.

The solution to this problem is to flush out the excess calcium ions by running a full cycle of your water heater.

Should I Flush My Tankless Water Heater?

Tankless water heaters are different from other types of water heaters. They do not store hot water for later use. Instead, they continuously produce hot water at all times.

Because of this, there is no need to flush them. However, if you notice any signs of corrosion, you may want to consider flushing your tankless water heater (see also ‘ Can Your Water Heater Explode? ‘) anyway.

Before You Begin A Water Heater Flush: What You Need To Know

There are several safety precautions you should take before beginning a water heater flush. Here are some things you need to know about doing a water heater flush safely and easily.

1. Safety Precautions

First, make sure that your home has been properly ventilated. When you begin a water heater flush, you must be wearing protective clothing and equipment.

2. Get Rid Of The Gas Line

When you begin a water heater cleanout, you must disconnect the gas line. Otherwise, you could end up with an explosion.

3. Disconnect Electrical Wires

When you begin a water heater cleanup, you must disconnect the electrical wires. Doing so prevents electrocution.

4. Use A Pressure Washer

A pressure washer is a great tool for cleaning your water heater. Using one of these tools will help remove buildup, scale, rust, and sediment.

5. Follow Directions Carefully

Make sure that you follow the directions carefully. If you don’t, you may damage your water heater or cause injury. 

How To Flush Your Hot Water Heater

How To Flush Your Hot Water Heater

Step 1 – Turn Off The Power Supply

Before starting the flush procedure, make sure that all power supplies are turned off. You do not want to turn on the power supply while you are working on the water heater.

Step 2 – Remove The Drain Cover

After turning off the power supply, remove the drain cover located near the bottom of the tank. Be careful when removing this part because it has sharp edges.

Step 3 – Unplug The Unit

Next, unplug the electrical cord connecting the water heater to the wall outlet. Make sure that the plug is removed before you start the flush procedure.

Step 4 – Disconnect The Gas Line

Next, disconnect the gas line connected to the water heater. Again, make sure that the plug is disconnected before starting the flush procedure.

Step 5 – Start The Flushing Process

Now, you will need to use a garden hose to fill the tank with cold water. Once the water level reaches the overflow pipe, stop filling the tank.

Step 6 – Close The Drain Valve

Once the water level reaches the top of the tank, close the drain valve (see also ‘How To Unclog A Drain Valve: The Complete Guide‘) located at the base of the tank. This allows the water to drain out of the tank.

Step 7 – Wait For The Tank To Empty

Wait until the water level drops below the overflow pipe. Then, open the drain valve again to allow more water to drain from the tank.

Step 8 – Fill The Tank With Cold Water

Fill the tank back up with cold water. After the water fills the entire tank, wait for about five minutes.

Step 9 – Repeat Steps 2 Through 8

Repeat steps 2 through 8 one more time. The purpose of this step is to completely empty the tank.

Step 10 – Replace The Drain Cover

Replace the drain cover after completing the last step.

Frequently Asked Questions

Should I Drain My Water Heater Periodically?

Yes! It is always recommended that you drain your water heater periodically. This prevents sediment build-up and other issues that may occur over time.

Can I Use Saltwater to Flush My Hot Water Tank?

No! Using saltwater to flush your water heater could damage your tank. Instead, use fresh water.

What Should I Do When My Tank Is Full?

If you notice that your tank is full, stop flushing immediately. This could cause problems such as rusting pipes and valves inside the tank.

Why Does My Tank Keep Filling Up?

The reason why your tank keeps filling up is due to the fact that you have not drained enough water from the system.

If you continue to run the water heater without draining the water, then the water in the tank will eventually be heated by the heaters.

How Long Can I Run My Water Heater Without Flushing?

You should only run your water heater for two weeks or less. However, if you regularly drain your tank, then you can keep running your water heater for longer periods of time.

How Often Should I Flush My Water Heater?

You should drain your water heater every six months. However, if you are using the unit on a daily basis, then you might want to drain it once per month.

How Long Does It Take To Flush A Water Heater?

It takes approximately 20 minutes to complete a normal flush. Nevertheless, your first attempt may take longer. In most cases, the whole process should be completed within an hour. 


Flushing your hot water heater is an important maintenance task. By following these simple steps, you can ensure that your water heater lasts as long as possible.

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By Anthony Barnes

Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age