6 Reasons Why You’re Finding Water in Your Water Heater Pan

Lauren Murphy
Written by Lauren Murphy
Updated October 26, 2021
A bright bathroom with a vintage bathtub and plants
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Water in your water heater pan can be the first sign of a leak

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A water heater pan, also known as a water heater drain pan, is a pan that sits underneath your water heater to collect water in the event of a small leak. Ideally, they should be dry—but if you’re finding water in your water heater pan, that means your heater is leaking. 

Leaks can happen for a number of reasons. Sometimes the problem is serious and other times they are totally fixable. If you’re feeling confident, you can check for leaks at the water pipe fittings and tighten the pipe connections if you need to. It may be a simple issue with your valves or it will warrant a call to your local water heater technician.

To diagnose the problem on your own, arm yourself with a flashlight and a paper towel and search for wet spots by wiping the towel along pipe fittings and your water heater tank. There are a few things to look out for.

1. Leaking Drain Valve

A hot water heater’s drain valve is threaded into the bottom side of the tank and flushes out any sediment that collects inside.

If you find water in your water heater pan, a leaky drain valve is likely the culprit. Check the valve’s outlet with a paper towel to see if this is where your water is coming from.

Try tightening the valve by hand if the leak is coming from the drain valve nozzle, as the valve might not be completely closed. If the valve still drips water after tightening, you’ll need to replace it.

2. Damaged Internal Tank

If the leak isn’t coming from your drain valve, look at the tank itself next. A leaky internal tank causes water to slowly seep out and pool at the bottom of the tank and water heater pan. 

The tank incurs damage when sediment builds up inside, causing it to crack. Draining your hot water heater on a regular basis to flush out sediment prevents this issue. 

In this scenario, the best course of action is to contact a local professional plumber to determine whether or not you’ll need to purchase a whole new tank.

3. Faulty Temperature-Pressure Relief Valve

Hot water running in a bathtub
Kazuki Kimura/EyeEm via Getty Images

The temperature-pressure relief valve automatically opens to discharge hot water in case the tank reaches an extremely hot temperature or high pressure. Typically, this is a brass valve mounted near the top of a hot water tank with a pipe coming down to about 6 inches off the ground. 

Wipe a paper towel on the bottom of the downtube. If it’s wet, this is the source of your leak. In most cases, you’ll need to completely replace this valve.

4. Corrosion

If you’re finding water in your water heater pan, a leak due to deep internal corrosion is the worst-case scenario. This may only be a small leak at first, but iit will gradually get worse and, occasionally, it causes a blowout that leaves your utility room a sopping mess. 

Unfortunately, there aren’t many early warning signs for this problem because tanks rust from the inside out. That said, some possible signs to look out for are corrosion around the base of the tank or a rusty wet stain on the ground underneath. You’ll need to completely replace your water heater tank if it’s internally corroded.

5. Condensate Dripping Down Flue

Condensate from combustion water vapor can run down your water heater duct into the flue through the center of a gas-fired heater and drip down into the center of the firing chamber. Eventually, the bottom of the fire chamber can rust through and allow water to drip into the water heater pan.

Watch for drips from the duct and listen for a sizzle as it drips into the firebox. If this has been happening continuously for a long period of time, you will see large piles of rust around the firebox.

Call a professional plumber to diagnose the problem and determine your next steps.

6. Leaking Pipes Above Water Heater

If you can’t find a leak coming from any of the parts on your water heater, it could be a leaky pipe or valve located above the water heater. A lime buildup commonly causes these leaks that start as dampness and escalate to trickles over a few weeks. 

You can check by wiping around the top of the tank with paper towels and looking out for any wetness or hire a plumber to investigate.

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