Why is my water heater pressure relief valve leaking? Top causes & simple fixes

A water heater pressure relief valve leaking can signal underlying issues that need to be addressed before they turn into major problems. We’ll cover the common causes, and how you can troubleshoot and fix it.

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Important: The information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Common causes of a water heater leaking from the pressure relief valve

The water heater pressure relief valve, or temperature and pressure (T&P) valve, is a safety mechanism that releases water if the tank’s pressure or temperature exceeds safe limits. It prevents dangerous pressure buildup, which could cause damage or even a hazardous explosion. However, when your water heater relief valve is leaking, it’s often a sign that something is wrong with your system.

Here are the most frequent reasons why water dripping from the water heater relief valve occurs:

High water pressure in the tank

If the pressure inside your water heater exceeds 150 psi, the water heater pressure valve dripping is your system’s way of protecting itself. High pressure can be due to factors such as an increased water supply pressure or thermal expansion inside the tank.

Overheating due to thermostat issues

A thermostat set too high can cause the water to overheat and expand, creating excess pressure. This is a common reason for hot water heater pressure valve leaking. Overheating could also occur if the thermostat is malfunctioning, pushing the water temperature beyond safe levels.

Faulty pressure relief valve

If your water heater pressure relief valve is leaking even when pressure and temperature are normal, the valve may be faulty. Over time, the valve can wear out, corrode, or develop sediment buildup, causing the water heater relief valve to drip unnecessarily.

No expansion tank in your system

Without an expansion tank, the expanding hot water has nowhere to go, leading to pressure buildup in the main tank. This can cause the water heater to leak from the relief valve as the T&P valve attempts to release the pressure.

Sediment buildup causes overheating

Over time, sediment can accumulate at the bottom of the water heater tank, reducing its efficiency. This can lead to overheating and increased pressure, forcing the water heater pressure valve to leak as the system tries to balance itself.

How to troubleshoot a water heater pressure relief valve leak

If your water heater is leaking from the relief valve, follow these steps to troubleshoot and fix the problem:

Test your water pressure

1. Test the water pressure in your home using a pressure gauge, which can be purchased at most hardware or home improvement stores.
2. Locate a water outlet in your home, such as an outdoor faucet or a washing machine connection, where you can attach the pressure gauge.
3. Turn off all water appliances and faucets in your home to get an accurate reading.
4. Attach the pressure gauge to the chosen water outlet and open the valve slowly to allow water to flow into the gauge.
5. Read the pressure displayed on the gauge. If the pressure exceeds 80 psi (pounds per square inch), it is considered high and could be the cause of the water heater overflow.

Check the thermostat settings

1. The temperature controls are typically found on the front of the unit near the bottom or on the side of the tank. Some may have a dial or digital controls.
2. Verify the current temperature setting on the water heater. The recommended temperature setting for most households is between 120 to 140 degrees Fahrenheit (49 to 60 degrees Celsius).
3. For water heaters with a dial: Turn the dial towards the lower temperature setting to reduce the temperature.
4. For water heaters with digital controls: Use the control panel to lower the temperature setting to the desired level.
5. After adjusting the temperature setting, allow some time for the water heater to stabilize at the new temperature. Monitor to see if the dripping from the overflow pipe stops.
6. Make sure to follow the manufacturer’s instructions and safety guidelines to prevent accidents.

Flush the water heater tank

1. Turn off the water heater and let it cool down. For gas heaters, set the gas control valve to the “pilot” position.
2. Locate the drain valve on the tank. It is typically located near the bottom and looks like a hose bib with a threaded end.
3. Attach a garden hose to the valve and run it to a drain, utility sink, or outside.
4. Open a hot water faucet in your home to allow air into the system and help with drainage.
5. Open the valve and allow the tank to drain completely. Be cautious as the water can be hot.
6. To further flush the tank, turn the cold water supply back on for a few minutes while the drain valve is still open. This helps to flush out any remaining sediment that may be settled at the bottom of the tank.
7. Once the water runs clear and you have flushed the tank adequately, close the drain valve by turning it clockwise.
8. Disconnect the hose from the drain valve.
9. Turn on the water supply to refill the tank. Keep the hot water faucet open to release any air trapped in the system.
10. For electric heaters, switch the power back on at the breaker box. For gas heaters, set the gas control valve back to the desired temperature.

Inspect the pressure relief valve

If the water heater relief valve is leaking despite normal temperature and pressure, the valve may be worn out or faulty.

1. Before starting any maintenance, ensure the water heater is turned off, and the water inside has cooled down to prevent burns.
2. Have a bucket, towels, and plumbing tape on hand.
3. The pressure relief valve is typically located on the top or side of the water heater and has a long handle or lever. Lift the lever on the pressure relief valve to allow a small amount of water to release. This tests if the valve is working correctly.
4. If water does not flow out or the valve continues to leak after releasing the lever, the pressure relief valve may be faulty and needs to be replaced.
5. Connect a hose to the drain valve at the bottom of the water heater to drain a few gallons of water, reducing pressure inside the tank.
6. Once the water heater is drained, use a pipe wrench to unscrew the old pressure relief valve from the tank.
7. Wrap the threads of the new pressure relief valve with plumbing tape to create a tight seal.
8. Install the new valve by screwing it into place and tightening it securely.
9. After replacing the valve, turn the water and power back on to the water heater.
10. Lift the lever on the new valve. Water should flow out of the valve.

Consider installing an expansion tank

If your home doesn’t have an expansion tank, installing one can prevent pressure buildup caused by thermal expansion. This will reduce the chance of your water heater pressure relief valve dripping by providing a place for excess water to go when it expands.

1. Choose an expansion tank that matches the water heater’s capacity and pressure specifications. Refer to the manufacturer’s guidelines for compatibility.
2. Turn off the power supply to an electric water heater or set the gas control valve to the “pilot” position for a gas water heater. Shut off the main water supply to the house.
3. Connect a garden hose to the drain valve at the base of the water heater and drain a few gallons of water to relieve pressure.
4. Install the expansion tank on the cold water supply line near the water heater.
5. Position the tank vertically with the air valve facing upwards.
6. Cut the cold water supply line and solder a tee fitting into the line.
7. Connect the expansion tank to the tee fitting. Ensure the tank’s inlet is connected to the cold water line and the outlet to the water heater.
8. Use pipe straps to secure the expansion tank to the wall or a nearby support structure.
9. Use a tire pressure gauge to check the air pressure in the expansion tank. It should match the water pressure in the plumbing system, typically around 50-60 psi (pounds per square inch).
10. Turn on the main water supply and check for any leaks around the expansion tank and fittings.
11. Once the expansion tank is installed and there are no leaks, restore power to the water heater and turn on the gas supply if applicable.

People also ask

Why is water leaking from the pressure relief valve on my water heater?

The most common reason water is leaking from the pressure relief valve on your water heater is due to excessive pressure or temperature inside the tank. The temperature and pressure (T&P) relief valve is designed to release water when the pressure or temperature exceeds safe levels. If your water heater is over-pressurized or overheating, the valve will open to release some water and prevent damage.

How do I stop my water heater pressure relief valve from leaking?

To stop your water heater pressure relief valve from leaking:

1. Check the water pressure in your home using a pressure gauge. If it’s too high (above 80 psi), install a pressure reducing valve to regulate it.
2. Inspect the thermostat and lower it if the temperature is set too high (above 120°F).
3. Flush the water heater tank to remove sediment buildup that could be causing overheating.
4. If the valve itself is faulty or worn out, replace it with a new T&P valve.

Is it normal for a pressure relief valve to drip?

No, it is not normal for a pressure relief valve to drip continuously. Occasional releases due to minor pressure fluctuations are normal, but constant dripping could indicate high pressure, overheating, or a faulty valve. If the water heater pressure relief valve is leaking continuously, it should be addressed to prevent further damage.

Why is my hot water heater leaking water from the relief valve but not the cold water?

If your hot water heater is leaking water from the relief valve, but cold water is unaffected, it’s likely because the pressure and temperature in the hot water tank are too high. The T&P valve is designed to relieve excess pressure, which can build up due to thermal expansion when heating water. Cold water doesn’t undergo this expansion, so the valve only leaks when the hot water side is over-pressurized.

Can I fix the water heater pressure relief valve leak myself?

Yes, you can often fix a water heater pressure relief valve leak yourself by:

1. Checking the water pressure and adjusting it if necessary.
2. Lowering the water heater’s thermostat to reduce overheating.
3. Flushing the tank to remove sediment buildup.
4. Replacing the pressure relief valve if it’s faulty. However, if you’re unsure of the cause, it’s always a good idea to consult a professional to avoid further damage to your system.

Wrapping up

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