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Leaking water heater dripping from drain valve

Why is My Water Heater Leaking?

If you find your water heater leaking, you need to take action immediately. A leaking water heater may seem like a minor inconvenience, but in reality, it can quickly turn into a major problem. The average water heater has a 50-gallon tank and whenever water leaves the tank (drawn or leaking) cold water will quickly refill it to capacity.

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As the tank is constantly refilling from the water heater leak, the area surrounding your tank will flood. Even a small amount of water leaking from your water heater can cause damage to your floors, sub-floors and walls. A significant flood could lead to hefty repair bills and damage to personal property.  Water heater leaks can also be a health concern and lead to mold and mildew.


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A water heater leak won't go away on it's own. Over time, it'll get worse.

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

Unfortunately, there's also times when you'll find your water tank leaking and you'll either need to call a plumber to make the repairs, or purchase a new water heater. 

Either way, this article will help you determine why your water heater is leaking and what you should do to resolve the problem.

Let's get started!

Shutting off gas valve

Water Heater Leaking: What to Do First

If your water heater leak is not obvious, then you may want to do a little troubleshooting before turning off the water supply. Just because you have water under your water heater doesn't mean that your water heater is leaking.

Furnace drain lines, water softener discharge lines, condensation, and other plumbing could be the source. These things can easily make it look as though your water tank is leaking, when in fact, the problem isn't your water heater at all.

If you can't identify where the water is coming from, you can dry the area and place some paper towels or newspapers down. Check back over the next couple of days. If the water returns, and you still can't identify the source, there's a good chance your water heater is leaking.

Dial valve on a copper pipe

Turn Off the Water Supply

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

On top of your water heater there should be two pipes. One will be warm to the touch and the other cold. Some manufacturers even identify them with red and blue collars or paint.

The pipe that's cold is the water supply line. It allows cold water to enter your water heater when hot water is drawn. Follow the line and look for a shutoff valve. Most water heaters have a shutoff 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 type handle. Pull or turn the handle down to shut off the water supply.
  • Dial Valve - Dial valves (also called gate valves) have a wheel that needs to be turned clockwise to turn off the water supply. Turn the dial until it stops.

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

In this case, you may need to turn the water off using your home's main shut-off valve. This will shut down all the incoming water to your house, including the water supply to your water heater.

Electrical Panel

Turn Off the Power

With your water turned off, it's now time to turn off the power to your water heater. The process is different for gas and electric heaters:

Gas Water Heaters

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

How to Turn Off a Gas Water Heater

  • Locate the valve on the gas supply line. The line is usually within a couple feet of your water heater. It's located near the bottom and connects to the gas control valve.  
  • Turn the valve on the gas supply line clockwise until it stops. This will shut off the gas supply to the water heater.

Electric Water Heaters

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

How to Turn Off an Electric Water Heater

  • Locate the breaker to your water heater in the household electrical panel. It will be on a dedicated circuit breaker.
  • Flip the breaker to OFF.

Now with your water and power turned off, it's time to roll up your sleeves and do some troubleshooting!

Corroded water supply inlet valve

Troubleshooting Hot Water Heater Leaks

Right now our goal is to identify the source of the water heater leak. Once you determine why your water heater is leaking, we'll show you how to fix the problem.

As a general rule, when a water heater leaks from the top the problem can be repaired. In fact, you may be able to do the fix yourself.

Unfortunately, when your water heater is leaking from the bottom, there's a greater chance that the problem is serious . . . but not always.

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

Top of water heater

Cold Water Inlet / Hot Water Outlet

If your water heater has a pool of water on top, there's a good chance that the source of the leak is either the incoming water supply valve, cold water inlet, or the hot water outlet.

Whenever there are pipe connections, there's a higher chance of a leak. Follow the cold and hot water pipes. Do you see any water? Are the fittings tight? Is there any leakage around the shutoff valve on the cold water supply line?

The fix to any of these problems could be pretty easy and you may be able to do it yourself. Here's what to do.

T&P Relief Valve

T&P Relief Valve

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

When pressure builds within the tank to an unsafe level, the T&P valve relieves the tank pressure by opening the valve and allowing some of the water out of the tank.

This will prevent the tank from bursting or exploding!

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

How to Determine if the T&P Valve is the Source of the Leak:

  • Inspect the Tank: Check the area where the T&P relief valve enters the tank for signs of a leak.
  • Inspect the Valve: If the T&P relief valve is in the closed position and water is flowing from the attached pipe, the valve is defective and needs to be replaced.
  • Inspect the Valve: If the T&P relief valve is in the open position, it may be relieving excessive pressure from the tank (which is forcing the valve open). If this is the case, the leak is generally fixable, but the situation should be taken very seriously. We highly recommend calling a professional plumber.

Since the T&P relief valve is a safety device, and if this is the source of your leak, it's important that the valve is either replaced, or a plumber is called as soon as possible.

A T&P relief valve issue does not necessarily mean you'll need to purchase a new water heater, but the leak does need to be addressed. 

Once you determine that the problem is coming from the T&P valve we'll do some additional troubleshooting to try to isolate the problem. If the solution is to replace the valve, we'll show you how. 

Rheem SP12112G Brass Drain Valve

Drain Valve

The drain valve is located near the bottom of the tank and is used to drain the water when repairs and/or maintenance tasks are required.

How to Determine if the Drain Valve is the Source of the Leak:

  • Verify that the drain valve is completely closed.
  • If the drain valve is closed, and there's moisture coming from the drain opening, then the valve may be faulty and will need to be replaced. 
  • Check the area around the drain valve where it enters the tank. There should be no signs of moisture. If you do have moisture where the drain valve enters the tank, it's likely that you have an internal tank leak

Unfortunately, many manufacturers install low quality drain valves in their water heaters, so it's not uncommon for this to be the source of your leak.

Here's what to do next if your leak is coming from the drain valve.

Leaky water heater tank on bottom

Internal Tank

Water heaters have a steel internal tank which is wrapped in insulation and then enclosed within an outer visible skin.

If the internal steel water tank is leaking, you won't be able to see it by looking at the outer skin. In most cases, you'll notice water under the water heater since the most likely way for it to escape is from the bottom.

When you were inspecting your drain valve and T&P relief valve, you may have noticed moisture where the valves entered the tank. If this was the case, there's a good chance that your internal water tank is leaking.

Even with the best care, water heater tanks break down. Age and deterioration takes a toll and eventually the tank will begin leaking.

There are preventative measures you can take such as, treating hard water and performing regular maintenance, but eventually the inevitable will happen and you'll have a leaking water heater.

If your internal tank is leaking, your options are pretty limited.

Blue prints with plumbing tools

How to Repair a Leaky Water Heater

If the problem appears to be minor, and you have experience doing your own home plumbing repairs, you may choose to fix your leaking water heater yourself. 

But many homeowners are more comfortable hiring a plumber to make the repairs. The decision really depends on your comfort level and the complexity of the repairs.

Top of a gas water heater

Cold Water Inlet / Hot Water Outlet Repairs

If you have a leak coming from the area where the cold water inlet or hot water outlet connects to the water heater, you may be able to fix it by tightening the connections with a pipe wrench.

If tightening the connectors doesn't stop the leak, then you should replace the flex lines that supply the cold water (or hot water). The video below will show you how.

Watch the Video


Replacing a T&P Relief Valve on a Water Heater

T&P Relief Valve Repairs

There are three main reasons you may have water leaking from your T&P relief valve:

  • Faulty valve
  • Clogged valve
  • Excessive PSI and/or water temperature within the tank

Since the T&P relief valve is designed to prevent your water heater from overheating and developing excessive pressure within the tank, it's a good idea to do a little extra troubleshooting before assuming the valve is faulty and simply replacing it with a new one.  

This article will show you how to determine if the problem is a faulty T&P relief valve or if the valve is actually doing its job. If it's the latter, then your water heater requires immediate attention.

Leave the heater's water and power off and call a professional right away.

The following video explains the role of the T&P relief valve and what causes it to leak.

Watch the Video


It's also not uncommon to notice water leaking from the threads of your T&P relief valve where it attaches to the tank. If this is the case, you'll need to remove the T&P valve and check the tank for signs of rust or corrosion.

If you see signs of rust or corrosion it's an indication that the problem is with the internal tank. Unfortunately, you'll need to purchase a new water heater.

However, if the tank appears to be in good condition, you can wrap the threads of the T&P valve with Teflon tape and screw it back into the tank. It may simply not have had a good seal.

Keep an eye on your water heater for the next few days to see if this resolved the leaking problem.

How to Replace the T&P Relief Valve

If you determine that the valve is faulty and needs to be replaced. You can find step-by-step directions here, or follow along with this instructional video.

Watch the Video


Connecting a hose to a water heater drain valve

Drain Valve Repairs

If your water heater is leaking from the drain valve, it is generally one of two things:

  • There is debris inside the valve preventing it from fully closing
  • The drain valve is faulty

First we need to rule out that a clog is preventing the drain valve from closing. Here's what to do:

How to Determine if a Drain Valve is Faulty:

  • Place a bucket under the valve and turn the dial counter-clockwise. If there's not enough space between the floor and the drain valve for a bucket, you may need to attach a garden hose.
  •  Once the drain valve is open it should flush out debris. If it's been awhile since you've flushed your water heater tank, it's possible that your drain valve will clog. Here's how to address the clog.
  • Allow the water to flow through the valve until it runs clear. Then close the drain valve.
  • If the drain valve is still leaking, the valve is faulty and needs to be replaced.

Unlike the T&P relief valve, the drain valve is not a safety device. If you're unsure about replacing the valve yourself, or don't have time to get to it right away, you can simply buy a brass garden hose end cap and screw it onto the drain valve threads

This should stop the leak until you're able to replace the drain valve.

How to Replace a Drain Valve

Changing a drain valve is relatively easy, and something you can do yourself once you buy a new valve. Always be sure to purchase one that's compatible with your water heater.

In order to replace a drain valve, you'll need to drain the tank. Be careful not to come in contact with the hot water.

Water heaters are usually factory-set to heat water to 125°F, which is hot enough to inflict first degree burns to skin on contact. And, if the water temperature was set to maximum, the water could be anywhere from 160° to 190°F which could result in serious injuries!

The video below will show you how to replace a drain valve.

Watch the Video


Internal Tank Leaks

If your water heater is leaking from the bottom of the tank, it suggests that there's a serious internal problem.

NEVER attempt to disassemble your water heater and perform internal repairs.

If your internal tank is leaking, you really only have one viable option. You'll need to replace the water heater. Internal tank leaks can not be repaired and the leak will only get worse.

However, if the water heater leak isn't too bad, and its installed in a basement or garage, you could buy yourself some time and just keep an eye on it. 

Although we don't recommend this approach, a minor leak likely won't do too much damage on a cement floor, especially in a garage. It could allow you to budget for a new water heater, rather than going in debt or buying an inexpensive lower quality unit.

If you do choose to go this route, we highly recommend purchasing a water alarm and positioning the sensor at a distance that will alert you to a serious leak.

Plumbers Wrench

Repair or Replace your Water Heater

As we discussed above, when you find water under a water heater the problem can be serious and action should be taken as quickly as possible.

Depending on the type of leak, you'll either need to repair or replace your water heater. Although, many of the repair fixes can be performed by the homeowner, frequently people prefer to call a professional plumber.

Your comfort level in tackling DIY projects will likely be the determining factor.

Water heaters generally last 8 to 12 years. So if your leaking water heater is nearing old age, you may choose to replace it with a new energy efficient model rather than pay for repairs.

New water heaters are far more energy efficient, which means they will save you money each month in operating costs. They'll also be under warranty, so any issues for the next couple of years will be covered.

We recommend considering the cost of repairs and the age of your water heater when you make your decision on whether to repair or replace your water heater.

But if you're still on the fence, this article will provide you with 5 warning signs of when you should consider buying a new water heater.

Red questions on a white background

Common Questions

Your water heater is one of the main appliances in your household. When it isn't operating correctly, it'll make its problems known. Either by not delivering hot water, creating unusual noises, or leaking.

Chances are, you have some questions. Here are some of the most common questions homeowners have in regards to water heater issues:

Who Do You Call if Your Water Heater is Leaking?

If you've determined that your water heater leak is beyond your skill set. You need to call a professional plumber at 1(888) 594-4431. They'll be trained and prepared to handle any issue they encounter, and can offer advise on whether you should repair or replace your water heater.

How Do I Get Rid of My Old Water Heater?

If you hire a plumber to replace your water heater, in most cases they'll get rid of the old one for you. However, if you're replacing the water heater yourself, you'll need to find a way to get rid of it on your own. This article will give you several options

Should I Upgrade to a Tankless System?

Maybe. Tankless water heaters are wonderful and have many advantages. But they aren't for every homeowner. We recommend reading our Tankless Buyers Guide to see if making the switch is a good move for you. There's a lot to consider, so take your time to be sure it's the right thing to do.

Is it Dangerous to Have a Leaking Water Heater?

Yes, if your water heater is leaking because the T&P relief valve is releasing pressure from within the tank, then the situation could be extremely dangerous. Your water heater is malfunctioning and causing either the internal tank pressure to be above 150 psi or the water temperature to be above 210°F. Turn off the power and call a professional immediately.

However, in most cases, water damage is the biggest concern. Repairing damaged floors can be expensive and it'll be critical that the clean-up is properly done or you may develop mold and mildew. Mold and mildew can be a health hazard and can cause serious respiratory problems.

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