Water Heater Overflow Valve Leaking: What to Do

If you have a water heater, you probably already know that it comes with an overflow valve. This valve, which is also known as the temperature and pressure relief valve or simply the relief valve, is important since it helps relieve pressure from the water heater. Remember: water expands when it’s heated, which means the pressure in your machine is high as it heats your bathwater. If this pressure has nowhere to go, it will eventually cause your water heater to explode.

The problem with overflow valves is that it’s hard to determine whether they’re leaking or not since they’re supposed to release some amount of water. After all, it’s their job to discharge some water from the water heater to relieve the pressure. So how would you know if the valve is just doing what it’s supposed to or if it’s already leaking? This guide can help you answer this question.

Find Out Where The Leak Is

If the overflow valve has released a small amount of water at one time, it probably is just doing its job and there’s no need for you to worry. But, if the valve continually drips out a slow leak, or if it releases a large amount of water in a sporadic pattern, then there definitely is a problem. Of course, if the leak is coming from the threads where the valve has been screwed on the water heater, these threads have to be fixed ASAP.

If The Leak Is From The Surrounding Area

As mentioned above, the leak from your overflow valve may come from the threads that it’s attached to and not from the valve itself. In this case, fixing it is easy since you only need to turn off the water heater, unscrew the overflow valve, apply plumbers’ pipe compound on the threads, and reattach the valve.

If The Leak Is From The Valve Itself

If the overflow valve sporadically lets out a large amount of water, the problem usually lies with the water heater’s thermostat. More likely than not, the thermostat has caused the temperature in the heater to rise to abnormal levels, causing the pressure inside to rise and making it necessary for the valve to let out water more often and in large quantities. You can solve this problem by replacing the faulty thermostat with a new one.

If the overflow valve slowly leaks out a small amount of water, the problem is usually the valve itself, which has become either too old or damaged. The best step to take is to replace the valve with a new one, which usually costs less than $20 and is easy to install. Simply drain some water from the heater, take out the discharge tube, remove the old valve, put in the new one, and reattach the discharge tube.

Take note that the problem may not stop at replacing the overflow valve. Even if the valve is new, it could still leak if you have a “closed system”; that is, the expanding hot water cannot flow back to the main water supply and has nowhere else to go. If this is the case, you’ll need to install an expansion tank, which will accommodate extra water from your heater and prevent it from leaking out through the overflow valve.