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Solved! Why is My Water Heater Pressure Relief Valve Leaking?

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The sight of water leaking from your water heater can be quite distressing but there’s no need to panic. There are several possible causes why the pressure relief valve of the appliance started to leak. This is an important safety feature of your water heater because this valve has a critical role to prevent the danger of an exploding water heater from excessive pressure or temperature. Most pressure relief valves are designed to activate when the pressure of the water heater goes beyond 150 PSI.

Let’s figure out the reasons why your water heater pressure relief valve is discharging water.



1. The First and Most Likely Cause is Excessive Water Pressure

Water Heater Installed in  a Simple White Kitchen




Too much pressure in your water heater is typically the main reason why the relief valve has opened. In that case, the valve is essentially doing its job and prevents that excessive pressure from damaging the water heater. The simplest way to figure out whether high water pressure caused the leak is to test the pressure with a suitable gauge designed to mount on your water pipes.




The pressure gauge needs to be installed on the outlet valve of the water heater. Normally, the pressure should stay consistently between 40 and 80 psi when this valve is opened. However, if you get a reading of pressure climbing above 150 PSI, you might experience a serious problem with excessive water pressure. An expansion tank is often the best solution to add some relief to the tank of your water heater.



2. Next, Check for High Water Temperature

Open Bathroom Faucet Allowing Water to Flow in a Sink Filled With Water




Not as common as having too much water pressure, a very high water temperature can sometimes cause the pressure relief valve to leak water. Checking the temperature of the water is fairly straightforward. It can be done with a meat thermometer at your hot water faucet. Normal temperature readings tend to sit around 120 degrees Fahrenheit. If it’s considerably higher than that, it’s possible that your water heater might be faulty. Keep in mind that it takes a water temperature of over 200 degrees Fahrenheit to activate the pressure relief valve.



3. If It’s Not the Pressure or the Temperature Then It’s Likely the Faulty Pressure Relief Valve

Close up of a Pressure Relief Valve From a Water Heater




The pressure relief valve can be triggered due to being faulty itself. This happens quite rarely considering that it’s a safety mechanism designed with a long lifespan. Given enough time and sufficient wear, however, the pressure relief valve of any water heater can eventually break down. There’s no way to repair the valve if it has failed and started leaking water. Your only option, in this case, is a full replacement which is reasonably affordable.



4. If Neither of These Are an Issue Then It Might’ve Been Installed Improperly

Close up of a Pressure Gauge From a Water Heater Installed in a Kitchen




Although it’s not very likely to happen, it’s possible for a technician to install the wrong pressure relief valve on your water heater. Not all safety valves are designed to activate at the same PSI threshold. Some models can trigger a water leak at a lower pressure level. Thankfully, improper valve installations are usually quick to detect right after setting up a new water heater. Wrong pressure relief valves start leaking immediately so this might not be the reason for the water discharge if it happens years after installing the water pressure.



5. If The Valve Hasn’t Been Used in a Long Time That Might Also Be an Issue

Poorly Maintained Water Heater Showing Excessive Wear




If you discover only a slight leak affecting your water heater, this might not be a cause for concern. It’s possible that your pressure relief valve hasn’t been triggered in a long time. This doesn’t necessarily indicate a faulty water heater but it’s recommended to replace the valve, especially if the water discharge gets more serious. Don’t bother trying to repair a leaking valve as it’s usually more trouble than it’s worth in the long run.



6. If None Of These Solve The Issue Then The Leak is Likely NORMAL

Yes, if after checking all the previous steps you haven’t found any of them to be an issue then a slight leak in the pressure relief valve will actually indicate that it is achieving its purpose and it’s working as intended.




A pressure relief valve is doing just that, relieving the pressure in the water heater and discharging small amounts of water at one time until the pressure reaches normal levels.

So if that seems to be the case in your situation then just ignore the leak altogether because your water heater is likely working as intended.

Only Fix the Leaking Pressure Relief Valve If You Know What You’re Doing

Even if you have some DIY skills and want to attempt repairing the water heater pressure relief valve, you should still probably call a professional technician when the pressure relief valve is leaking. While replacing the valve may not sound that complicated, a qualified plumber can handle the job more safely and effectively and they can help you avoid having your warranty voided for the entire water heater unit. They can also inspect the water heater to figure out the cause of the leak and decide on the best course of action. If you don’t know what you’re doing, you can expose yourself to the dangerous risk of water heater explosions.

By Stefan Bucur

Stefan is the founder and owner of Rhythm of the Home. He has 6 years of experience in home improvement, interior design, cleaning and organizing.

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