I just learned that my water heater can release water onto the floor via a pressure relief valve. I've cleaned up the mess (the valve is working fine, I just didn't notice the tiny cup previous homeowner had put it was filling up), but the root of the problem is that my overflow water didn't have anywhere to go - there is no floor drain in this space.

Is a condensate pump with the discharge routed up to the washing machine drain an acceptable solution? I have access to power so batteries won't be a problem for the unit.

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    There is the problem that a condensate pump may not tolerate the hot water. Plus the pressure relief valve will allow more water to exit than many condensate pumps are able to handle.
    – Hot Licks
    May 7, 2022 at 2:32
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    Why is the pressure relief valve discharging to begin with? May 7, 2022 at 4:36
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    Yes, normally the pressure relief valve should not be releasing anything. The releases suggest a problem - perhaps you need to install an expansion tank?
    – Armand
    May 7, 2022 at 5:11
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    If your leaking enough to need a pump there is a problem, the valve is going bad or there needs to be an expansion tank to allow for pressure changes as the water heater cycles you should not need a pump for a properly set up system in good shape.
    – Ed Beal
    May 7, 2022 at 7:25
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    The pressure release valve is for safety, prevents the tank from going boom. The only time it should work in normal conditions is when you test it. Problem might be as the other have said, or your thermostats are set too high. Think the recommended setting is around 120 degree F(to prevent burning of skin). If your water is much higher, then reducing the temperature setting might be all you need.
    – crip659
    May 7, 2022 at 11:34

1 Answer 1


You need to fix the problem that is causing your pressure/temperature relief valve to actuate. They are explicitly forbidden to be connected directly to a drain, because you should be aware that they are operating, so you know there is a problem, and act on it. They should never normally operate.

The most typical problem is either lack of, or a failed, expansion tank, causing excess pressure when a lot of hot water is used, replaced with cold water, and the cold water is heated (and expands) while no water is used, so pressure rises to unacceptable levels.

That is easily solved by adding (or replacing, if failed) an expansion tank, which can be located anywhere on the cold water supply after the check valve, meter, or PRV (regulator - Pressure Reducing Valve) that acts as a check valve, so long as there is no check valve between the tank location and the water heater (which would be unusual other than at the water supply entrance point.)

An additional possibility if you have been ignoring the operation of the relief valve is that it may no longer seal properly due to mineral build-up and need to be replaced, but if you don't first solve the basic reason for it operating at all, simply replacing the valve will generally not solve your problem.

If your municipal supply pressure is high, another possibility is that you have a PRV but that is not working right so your overall pressure is too high, causing the relief valve to actuate. Or you don't have a PRV but you need to add one. Those are common enough reasons, but far less common than the expansion tank.

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    The fact that the OP noted that the previous owner had a "tiny cup" set there indicates that this is an ongoing issue. It's possible that the relief valve is failing and has been steadily dripping over time, so that seems to be a reasonable thing to check first.
    – FreeMan
    May 7, 2022 at 12:53

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