Is discovering water leaking from the discharge pipe of your water heater a matter for serious concern? Imagine that one day you discover a puddle of water on the floor beneath your hot water heater. Immediately, alarm bells begin to ring in your head. Something is definitely wrong with your hot water heater’s overflow pipe. How expensive is this service going to be? A quick inspection for the source of the leak will point to the T&PR valve, a simple device that relieves excessive water pressure.

Water heaters only have three connecting lines. There will be a cold-water inlet line, a hot water outlet line and then a third line attached to a brass valve with a small lever attached to it. That’s the T&PR valve, the source of your water leak, but probably not your problem. Why? When working as designed, the T&PR valve safely releases water from the water heater if it becomes too hot inside the tank.

Because it is a safety mechanism, it will safeguard your home from dangerous super-hot water and possibly an explosion. Located on the top or side of your heater, the valve should be connected to a short pipe that leads downward toward the floor. In some installations it may connect to a floor drain. Some, but not all, discharge pipes are connected into a drain line in the floor. It is important to note that these lines are not overflow pipes since the function only when there is a water temperature and pressure problem.

If the water inside the heater becomes too hot, the valve works by opening and releasing the internal pressure. Your T&PR valve should have a “Do Not Remove” tag attached to it. The tag provides know-how about the preset limitations of the valve. You can determine the valves operational settings by examining the tag. Typically set for 120 degrees F, or a pressure of 150 PSI.

The valve is actuated by the presence of high pressure caused by high water temperature. As the valve opens, hot water will discharge out the drain pipe onto the floor or into the drain. It doesn’t have to open very much to work properly, but the fact that it opened at all means something is wrong with the water temperature. Clearly, water leaking from the discharge pipe is a call to further troubleshoot and service the water heater.

Be sure to check the T&PR valve at least once a year. This is a simple process, although you are exposed to hot water unless you observe precautions. Only one test is required, lifting the lever attached to the valve will release some hot water from the tank. The valve will open only a small amount, just enough to allow some hot water to escape. Let go of the lever and it should close the valve and cease further flow of hot water. This is an easy way to test the valve and you can forget about it until next year, or until you discover that nasty puddle.

Unless tested at least once a year, T&P valves may become corroded and fail to operate properly due to presence of certain chemicals in the water. You should replace a corroded valve yourself, or call a plumber to do so.. Generally, you should have a qualified technician or a licensed plumber replace a malfunctioning T&PR valve. It is a good practice to just use the same model and type of valve as the original when replacing a failed unit. Be careful to follow the manufacturer’s instructions, as well.

In summation, the cause of water leaking from the discharge pipe is either an unsafe water temperature or a failed T&PR Valve. Now you know what to do about it.

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