Dealing with an Overflowing Water Heater: Causes, Solutions, and Prevention

So, you’ve just discovered that your water heater is overflowing. Any water leakages can prove to be a complete inconvenience.

Both time and money become a  factor in the cleanup and repair of your water heater. What now? What caused the water heater to malfunction and create a whole mess of a problem? How can I troubleshoot? 

In short, your water heater may have overflowed due to broken valves, blocked valves, or leakages in the overflow pipes. In many cases, it can be because your temperatures are set too high which causes pressure inside the tank. It may be a simple valve replacement or you may have your water pressure values at an unsafe PSI. Whatever the case, there are ways to find out the potential cause and maybe even fix it. 

Let’s discuss how you can troubleshoot your overflow catastrophe. We will take you through the process to find the source of the problem and help you to understand more about what to look for in the future. This guide will teach you about safely checking all the components and making sure your water heater is properly functioning. 

Is an overflowing water heater dangerous?

Overall, the overflowing of a water heater CAN cause potential danger and harm. If you stay calm and turn off the heat and electrical supply immediately, there is no need to worry further.

Though you may be looking at the potential water damage and other headaches, the main cause for concern is electrocution.

As long as the power supply is cut off from the water heater, there is no risk of electrocution. 

In rarer cases, turning off the electricity can cause the system to short circuit, causing a fire in the location of your water heater, which is typically found in a basement or attic. 

Additionally, if you have a gas water heater, you do want to be mindful that natural gas can be extremely explosive so getting that heat source turned off immediately is key. Thankfully, these potential issues can be eradicated immediately as soon as you notice the problem.

Should I troubleshoot my overflowing water heater? 

For those of you who can’t get a technician out there immediately or want to try your hand at troubleshooting, it can be extremely helpful.

Not only will it help you to understand your water heater and its functions better, but you will learn how to safely approach them and feel more confident about regularly checking them.

Safety is Paramount

As previously mentioned, the importance of disconnecting the power supply is the biggest step in both the troubleshooting process and in maintaining your own safety. 

Relieving the pressure in your water heater is key- you don’t want to risk any more water damage or a potential explosion. By turning off the power supply, whether that is gas or electric, is going to prevent any further catastrophe from occurring. 

While there are many valves to explore, here are some of the key valves that may need replacing in the water heater:

  • The water pressure relief valve, also known as a T&P valve or safety valve, reduces the PSI in the water heater. 
  • The main valve is for turn on/shut off purposes. 
  • The float valve is responsible for water levels and is mainly associated with the overflow pipe

Troubleshooting A Water Heater That is Overflowing

Step 1: Turn off power and/or gas supplying the heater

The first step is to turn off any power supply to the water heater. Let’s relieve some of the internal pressure and take away the main safety risk electrocution. The main shut-off valve will typically be found in the front center of the water heater.

It may have a round dial ball valve or a gate valve which has a small lever for turning. They are also normally a bold color such as red, green, or black to stand out among other parts of the system.

Step 2: Check the tank for leaks

Start at the top of the tank where the pressure relief valve sits. All the connecting pipes will need to be evaluated to check for any dripping leaks. The pressure relief valve is the most common to cause a leak and if worn, the valve could need a simple replacement. I

f all checks out, you can move to the bottom to check the drain valve. If you notice a small puddle on the floor, the drain valve could be the source. Garden hose caps make nice quick fixes for a faulty valve until you can get the proper parts.

Step 3: Clean valves and check the seals 

Checking all the valves is key. For the overflow pipe, you’ll want to make sure the float valve isn’t compromised. If it is dirty, you can always remove and wipe clean with a cloth or rag.

The pressure relief valve is an important valve responsible for the safety of the pressure located inside the tank.

You CAN safely remove and install a replacement, however corrosion on the pipe may make it difficult without the proper tools and may require professional help. 

Step 4: Check the overflow pipe for leaking

The overflow pipe has a very important duty- it allows excess water to run outside instead of indoors, preventing water damage to your home. Without the overflow pipe, you risk flooding and leakages.

You will find the overflow pipe sitting at the top, parallel to the water heater. Signs of overflow pipe drainage include small puddles and either inconsistent or consistent drips of water. If you find any type of water coming from the area, you likely have a leakage in the overflow pipe.

Step 6: Replace any broken components (valves, overflow pipe) 

If you find out that you need a new valve or overflow pipe, you will want to research and make sure you find the correct part.

Visit your manufacturer’s website for all the product details and specs for each part. You may very well be able to find these parts at your local hardware store but check your manual or the website for specific information on the necessary parts. 

Step 7: Close hot water faucets

Make sure all of your hot water supplies are off on your main floors. The kitchen and bathroom sinks will need the hot water supply shut off so that you can re-establish the water pressure in your hot water heater.

Close hot water faucets

This will ensure that you get the right amount of pressure so your water heater can function both safely and properly for regular use. 

Step 8: Turn the power and gas back on

Once you have safely closed everything back up again, you will want to go ahead and turn the power to your water heater back on.

As previously mentioned, you will search for the dial that is bold and at the front of your water heater. Turn it back on once you are ready to test out your fix after troubleshooting. 

Step 9: Check to make sure the leaking has stopped and heater is functioning properly

Repeat all the above steps to ensure there are no more leaks. You’ll want to start by turning off the power supply and checking all of the connecting pipes and their valves for any drips.

If everything is functioning properly, there will be no signs of drainage and your water heater will be the proper PSI and temperature to ensure its functioning safely and efficiently.

If you continue to have issues, you may want to contact a professional for a second opinion. 

Why is my water tank overflowing?

If your water tank is overflowing, there are a number of reasons why this may be occurring. Here are some of the more popular reasons why your water tank would be overflowing:

  • The temperature setting is too high
  • There’s an issue causing pressure to increase beyond the valve threshold
  • The valves are not set properly and are exposed, leaving an open spot for water to leak
  • Faulty valves

When the overflow pipe is leaking, it is likely due to pressure causing the release valve to open and expel water from the overflow pipe. The Department of Energy recommends you keep your tanks set to 120 degrees fahrenheit, so anything beyond that can be lowered to avoid unnecessary pressure inside the tank. 

Do check the water pressure as well. It is recommended that the water pressure should remain at 80 PSI and anything higher can cause additional pressure inside the tank. This can damage your water heater, in addition to causing drainage and leaks. If your tank does not have a pressure reducing valve, you can always have one installed to maintain the safety and functioning of your water heater. 

When should I call a professional?

The main concern for water heater leaks and overflows is always safety. While you may be perfectly capable of turning off the electrical supply and proceeding with caution, it is always important to be aware of the risks and to follow up with a professional. If you have a natural gas water heater, you already know how explosive it can be. 

In rare cases, water heaters can cause a carbon monoxide buildup. It is important to consult with a professional, especially if you have a gas-heated home. You also risk electrical burns, water burns, and water pressure-induced explosions.. 

If you do decide to troubleshoot and haven’t come up with the main cause, calling a professional is the best way to address the problem.


It’s important to make sure your water heater is functioning safely and to its full potential while it is in regular use. If your water heater is overflowing, making popping or knocking noises, or acting strange troubleshooting could prove to be helpful if you are up for the challenge.

Now that you know a few key points in safely checking your water heater and what pressure and temperature are recommended, you will be able to monitor the system with no trouble going forward.

If you notice any leaks or anything functioning differently, you know that it can lead to both safety and performance issues. Calling a professional is sometimes the only solution, but knowing the steps to safely inspect the overflow is always a helpful tool to have.