Water Heater Leaking From The Bottom: Causes, Fixes, and Tips

Leaking Water Heater Bottom

You just found your water heater in a puddle of water, could it be that it is leaking from the bottom? What does that mean? and maybe more importantly, what should you do? First, keep in mind that water obeys the law of gravity. If you have a leak anywhere on or near your water heater, you'll find the evidence on the floor. So don't panic just yet.

Before you try to find the leak, you should turn off the power to your water heater. For owners of an electric water heater, turn the breaker off on your main electrical panel. If you have a gas water heater, look for the on/off dial located on the gas regulator on the side of your water heater. Set the dial to pilot or off. 

You'll also need to turn off the water supply to prevent further water damage. However, you should find the source of the leak first. Turning off the water supply beforehand will reduce the water pressure and could make finding the leak difficult. 

When a Water Heater Leaks from the Bottom

How to Turn Off the Water
  • Find the incoming water pipe to the water heater. There is usually a lever or dial on the pipe before it reaches the water heater.
  • Turn the dial clockwise to close the valve, or move the lever so that it juts out from the pipe in a "T" shape.
  • If your water heater does not have a shut off on the incoming water line, you'll most likely need to turn off the water to the entire house. We highly recommend hiring a plumber to install a shut off valve.  

Causes & Fixes: When a Water Heater Leaks from the Bottom

Temperature & Pressure Relief Valve

The Temperature and Pressure Relief Valve (also known as the T&P valve) is an important safety feature required for all water heaters. When the temperature within the tank becomes too high, the pressure may exceed safe limits and trigger the T&P valve to open.

The T&P valve is designed to automatically open and release the water through an overflow pipe. As the water is released, the pressure within the tank is reduced to safe levels.

The overflow pipe is attached to the T&P valve and runs the length of the water heater and ends a few inches above the floor.  Should the T&P valve need to release pressure from within the tank, the water will safely be discharged to the floor.

Inspect the inside of the overflow pipe.  If you notice any moisture, your water heater is most likely leaking due to the T&P valve. This is good news, because it may look like your water heater is leaking from the bottom, but it actually isn't!

Temperature & Relief Valve

Diagnose the Problem

First, determine if the T&P valve is opening because you have a pressure issue inside your tank.

  • Reduce the water temperature by lowering the thermostat.
  • Open the valve to the incoming water and turn the power back ON to the water heater.
  • Observe if water continues to flow thru the overflow pipe. You may need to monitor the situation for awhile.
  • If water is still being discharged, turn the water and power OFF to the heater.
  • You likely either have too much pressure within your tank, or a defective T&P valve.
Fix the Problem
  • If you have an internal pressure problem, it's most likely out of your hands. Make sure your tank is not connected to power and the incoming water supply is turned off. Then call a professional plumber to do the repairs.
  • If your T&P valve is defective, you can replace the valve yourself or hire a plumber to do it for you.

Replacing the T&P Valve

  • Check that both the power and water supply are off.
  • Drain the tank to a level that is below the T&P valve.
  • Open a hot water faucet close by to let air flow into the tank.
  • Using a pair of channel locks unscrew the faulty T&P valve.
  • Wrap Teflon tape on the threads of the new valve.
  • Screw the new T&P valve into the tank.

The Drain Valve

The drain valve is located at the bottom of the water heater tank. It's purpose it to allow you to drain the tank for routine maintenance, replacement, or when repairs are needed. 

Inspect the drain valve for moisture. You may notice water dripping or moisture around the base of the valve where it connects to the tank, or at the opening of the valve itself. 

It is also possible that the drain valve is simply loose. Use a wrench and tighten in a clockwise rotation until the valve is snug. Check the valve system nut or the valve handle, as they may be loose as well. 

Drain Valve

Fix the Problem
  • Your drain valve is faulty and needs to be replaced if it is still leaking after tightening.

Replacing the Drain Valve

  • Always check that your power and water supply are off.
  • Attach a garden hose to the drain valve to drain the water from the tank.
  • After the tank has completely drained, use a wrench to remove the old drain valve by turning it counter clockwise. 
  • Wrap Teflon tape on the thread of the new drain valve and screw it back into place with a wrench until it's snug.
  • After replacing the T&P valve or drain valve on an electric water heater, be sure that you fill the tank completely before turning on the power to avoid damaging the heating elements. 

Internal Tank Leak

The internal tank of a water heater is made from steel, and over time, steel will rust. The anode rod is designed to sacrifice itself to protect the steel, but overtime it will be eaten away if not checked and replaced periodically. 

Then there's sediment. Sediment is brought into your tank with the incoming water,  and it's also made up of rust and other destructive remnants from within your tank. It could be flakes of rust or pieces of your anode rod. Basically it is anything that settles on the bottom of your water heater.

Sediment  build-up within the tank is the most common cause of a tank breaking down and eventually leaking from the bottom. By following a routine maintenance schedule, sediment will be flushed from your tank helping to prevent future damage. 

If you find a puddle of water under your water heater, there's a good chance the problem is the internal tank.

Fix the Problem
  • If your internal tank is leaking there really isn't anything you can do other than purchase a new water heater. Unfortunately, there isn't a way to patch or fix a leak.

Preventing a Water Heater from Leaking from the Bottom

A water heater will have a typical service life between 8 to 12 years. Much of this depends on several factors such as the manufacturer, installation, fuel source and the hardness of water (hard water is bad news for water heaters).

Water heater maintenance can play a big role in getting the most from your water heater. The best part, it actually isn't that hard to do.

Checking the anode rod, testing the T&P valve, inspecting for leaks, and flushing your tank to remove sediment build-up are all tasks that help your water heater reach it's full service life potential. 

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