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Why Does My Water Heater Leak?

Why Does My Water Heater Leak?

If you discover that your water heater is leaking, you must act immediately. A leaking water heater may seem like a minor inconvenience, but in reality it can quickly become a major problem. The average water heater has a 50 gallon tank and when water leaves the tank (drained or leaking), cold water quickly fills it to capacity.


As the tank keeps filling up due to the water heater leaking, the area around your tank will become flooded. Even a small amount of water leaking from your water heater can damage your floors, sub-floors and walls. A major flood could result in high repair bills and damage to personal property. Leaks in the water heater can also pose a health problem and lead to mold.


A water heater leak will not go away on its own. It gets worse over time.

Not all hot water leaks are serious. Some can be fixed by simply tightening a connection. Others might need a little more attention, but you can probably do the repairs yourself, especially if you like DIY projects.

Unfortunately, there are also times when your water tank is leaking and you need to either call a plumber to fix it or buy a new water heater.

In any case, this article will help you figure out why your water heater is leaking and what you need to do to fix the problem.

Let us begin!

What to Do First: Water Heater Leaking 

Why Does My Water Heater Leak?

If your water heater’s leak isn’t obvious, it’s a good idea to do a little troubleshooting before turning off the water supply. Just because there is water under your water heater doesn’t mean your water heater is leaking.

Oven drain lines, water softener drain lines, condensation, and other plumbing items could be the source. These things can easily make your water tank look like it’s leaking, when the problem isn’t your water heater at all.

If you cannot see where the water is coming from, you can pat the area dry and place paper towels or newspaper on it. Come back in the next few days. If the water is coming back and you still can’t identify the source, chances are your water heater is leaking.

Switch Off the Water Supply

Why Does My Water Heater Leak?

The first thing you need to do is turn off the water supply to your water heater.

There should be two pipes above your water heater. One will feel warm and the other cold. Some manufacturers even label them with red and blue collars or paint.

The cold pipe is the water supply line. It allows cold water to enter your water heater when hot water is drawn off. Follow the line and look for a shut off valve. Most water heaters have a shut-off valve on the water supply line.

How to turn off the water

There are two types of valves commonly used:

  • Ball Valve – Ball valves have a lever handle. Pull or twist the handle down to turn off the water supply.
  • Selector Valve – Selector valves (also called gate valves) have an impeller that must be turned clockwise to shut off the water supply. Turn the rotary knob as far as it will go.


Although most water heaters have a shutoff valve on their water supply line, some do not.

In this case, you may need to turn off the water using your home’s main shut-off valve. This shuts off all water entering your home, including your water heater water supply.

Turn off the power

Why Does My Water Heater Leak?

If your water is shut off, now is the time to turn off the power to your water heater. The process is different for gas and electric heaters:

Gas water heater

Follow these steps to turn off the power to a gas water heater:

How to turn off a gas water heater

  • Locate the valve on the gas supply line. The line is usually a few feet from your water heater. It is located near the bottom and is connected to the gas control valve.
  • Turn the valve on the gas supply line clockwise until it stops. This shuts off the gas supply to the water heater.

Electric water heater

Follow these steps to turn off power to an electric water heater:

How to turn off an electric water heater

  • Locate your water heater’s circuit breaker in the household electrical panel. It will be due to a dedicated circuit breaker.
  • Turn OFF the circuit breaker.


Now that the water and electricity are out, it’s time to roll up your sleeves and troubleshoot!

Hot Water Heater Leaks: Troubleshooting Guides

Why Does My Water Heater Leak?

At this point, our goal is to identify the source of the water heater leak. Once you’ve determined why your water heater is leaking, we’ll show you how to fix the problem.

Generally, if a water heater is leaking from the top, the problem can be repaired. In fact, you might be able to do the repair yourself.

Unfortunately, if your water heater is leaking from the bottom, there is a higher chance that the problem is serious. . . but not always.

Here are some of the most common reasons why a water heater leaks:

Cold Water Inlet / Hot Water Outlet

Why Does My Water Heater Leak?

If your water heater has a pool of water at the top, the source of the leak is likely the water inlet valve, cold water inlet, or water outlet.

Any time there are pipe connections, there is a higher chance of a leak. Follow the cold and hot water pipes. Do you see water? Are the fittings tight? Is there a leak around the shut off valve on the cold water supply line?

The solution to any of these problems could be quite simple and you could do it yourself. Here’s what to do.

T&P Relief Valve

Why Does My Water Heater Leak?

The temperature and pressure relief valve (T&P relief valve) is a required safety device on all water heaters.

If the pressure in the tank rises to a dangerous level, the T&P valve relieves tank pressure by opening the valve and allowing some of the water to escape from the tank.

This will prevent the tank from bursting or exploding!

You can find the T&P relief valve on top of your water heater or on the side. Look for a copper or PVC pipe running down the side of the tank to the bottom. This is the T&P drain hose that connects to the relief valve.