Water Heater Leaking: What Should You Do?

What to Do When Your Water Heater is Leaking

A water heater leak may seem like just a minor nuisance, but it can quickly turn into a big problem. Even a small amount of water will cause damage to your floors, sub-floors, and walls. Keep in mind that a water heater leaking may be a symptom of a much larger problem. In extreme cases, a catastrophic and complete water heater failure can cause a significant flood that could lead to hefty repair bills and damaged personal property.

A leaking water heater can be a health concern. Damp and wet areas can sprout mold and mildew that can cause allergic reactions and asthma in some individuals. According to the EPA, some mold spores are toxic and can lead to serious health problems.

What Causes a Water Heater to Leak?

A water heater leak does not go away, it will only get worse. The best move is to always move quickly to find and fix the problem. If you've already determined that your water heater is leaking from the top or bottom, check out these articles:

  • Is your water heater leaking from the top? Click here
  • Is your water heater leaking from the bottom? Click here
What to do when your water heater is leaking

What to Do When Your Water Heater is Leaking

Follow these 5 steps to determine and resolve your leaking water heater problem:

Step 1: Determine the Source of the Leak

Not every small puddle of water found at the base of a water heater is due to a leak. A water heater and the pipes surrounding it, plus the other appliances typically found nearby, can form condensation, which can accumulate and drip to the floor; especially in a basement or during damp weather.

Furnace drain lines, water softener discharge lines and other plumbing can also be the cause of the leak. If a small amount of water is noticed under or near a water heater for the first time, dry the area and try to determine the cause by inspecting the water heater and its plumbing fittings for obvious signs of water leakage.

If none are found, inspect other nearby possible sources. Water faithfully obeys the laws of gravity, so pay particular attention to anything directly overhead, especially water pipes.

If still nothing is found, place some paper towels on the dry floor where you first noticed the water. Check the towels every few hours for dampness. If, after a day or so, the problem doesn't re-appear, it’s likely nothing to be concerned about. 

If, however, water reappears, and no other source can be found, it's likely your water heater leaking. The next steps will help you determine the cause. 

Step 2: Turn Off the Power

Once you determine that your water heater is leaking, the first thing you should do is turn off the power supply.

If you have an electric water heater simply locate your circuit breaker box and switch off the breaker for your water heater. Water and electricity can be a dangerous combination, so it’s important you do this before going forward.

If you have a natural gas water heater, it should have an on/off switch or dial. Make sure it is set to OFF. Avoid closing the gas shut-off valve if possible. These valves can be finicky and susceptible to failure over time, so it is best that they be left alone.

Step 3: Turn Off the Water Supply

  • WARNING: Water heaters are typically factory-set to heat water to 125 degrees Fahrenheit, which is hot enough to inflict first degree burns on skin on contact. When turned all the way up to maximum temperature (which can be anywhere from 160 to 190 degrees Fahrenheit) serious injuries can result from even indirect contact with the water. Always take precautions to avoid coming into contact with heated water.

If leak from your water heater is obvious and significant, turn OFF the water supply at the cold water shut-off valve. The majority of water heaters will have a valve located above the water heater to shut off the water supply. 

The cold water shut-off valve will either have a handle to pull down, or a gate valve (essentially a dial) that can be turned clockwise to close the valve.

  • Do NOT close the valve if you can not reach it safely without coming in contact with water.

If you have a large, serious leak and can not reach the incoming cold water shut-off valve safely, then you will need to locate the main shut-off valve to your house. Closing the house's main shut-off valve will shut down all incoming water to your home, but it should also stop the water supply to your water heater.

Shutting OFF the water supply should at least slow the leak down. It might even stop the leak entirely depending on where it's coming from. However, it may be necessary to turn the water supply back ON to help locate the leak if you have not identified it's origins yet. 

Step 4: Determine the Location of the Leak

There are a number of problems that can cause a  water heater to leak. Performing a quick inspection can help you make a proper diagnosis of the leak before you call a professional.

Here are a few of the most common places where a leak will originate:
  • The cold water inlet and hot water outlet connections - Check the points at which the inlet and outlet pipes connect to the water heater at the top of the unit. If this is the location of the leak, the fix may be as easy as tightening a few loose connections with a pipe wrench!
  • The temperature & pressure relief valve - Every water heater has a temperature & pressure relief valve located on the side (or top) of the tank with an attached pipe running down to the floor. This valve is a safety device that's in place if the water becomes too hot, or there's an excessive amount of pressure within the tank. The T/P valve relieves the tank pressure by allowing some of the water out of the tank. 1) Inspect the point where the T/P valve enters the tank for signs of a leak. 2) Inspect the valve itself. If the T/P valve is in the closed position and water is flowing from the attached pipe, the valve is defective. If the valve is in the open position, it may be relieving excessive pressure from inside the tank (which is forcing the valve open). A leak from this location is generally fixable, but it is a cause for concern and you should consider calling a professional.
  • The drain valve - Check the drain valve, located near the bottom of the tank. Make sure that it closes (and is closed) completely. Also check where the drain valve enters the tank. It should be watertight, with no signs of moisture.  A leak from this location is not a serious problem and can be fixed.
  • The internal tank - The internal tank is wrapped in insulation and then enclosed within an outer skin. If the internal tank is leaking, the leak will not be visible from the outside. Water will likely escape from the bottom of the tank when the internal tank leaks. The majority of water heater leaks are from the tank itself and are typically due to age and deterioration. If the souce of your water heater leak is the internal tank, the only fix is to purchase a new water heater

Step 5: Repair or Replace

As stated above, when a water heater leaks it can be a serious problem and action should be taken as quickly as possible. Depending on the type of leak you have, you'll either need to repair your heater or replace it. In both cases, it's highly recommended that you call a professional plumber to deal with the problem.

Improper repairs or removal of a water heater can cause larger leaks and even floods which could lead to serious problems, such as water damage. If you choose to replace your water heater yourself, you'll need to properly dispose of the old unit.

When you call a professional plumber they'll be prepared and capable of handling any issue they encounter. They'll even dispose of your old water heater. If you're replacing your water heater, you may want to consider moving to a tankless system.

Water Heater Leaking: Repair

How to Repair a Leaking 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 water heater yourself. In this case, your next course of action will depend on the source of the leak.

  • WARNING: Repairing water heaters can be difficult. Improper repairs of a water heater can cause larger leaks, and even floods which could lead to more serious issues. If you do not have  experience performing home plumbing repair, it's highly recommended that you call a professional plumber

Cold Water Inlet / Hot Water Outlet Leaks

Inspect where the cold water inlet and hot water outlet pipes connect to the water heater at the top of the unit.

 A leak here, if minor, may require no more than the tightening of a loose connection with a pipe wrench. Anything more significant should be repaired professionally. 

Temperature & Pressure Relief Valve Leaks

A leak from the temperature & pressure relief valve (T&P valve) may be caused by excessive pressure inside the tank or overheating. This pressure on the T&P valve will keep it open almost continuously, leading to your water heater leaking.

To check if this is the problem, reduce the temperature by lowering the thermostat setting. Then turn the water and power/gas to your heater back on and observe it for a period of time. If it continues to leak, shut everything off immediately and call a professional.

If you determine that the cause of the problem is not excessive pressure or overheating, then you may have a faulty valve. Place a bucket or container under the T&P discharge pipe and open the T&P valve by pulling the tab on the valve up so it’s pointing straight out.

Doing this will flush the valve out and remove any debris that may be causing it to work improperly. If after flushing the valve it's still leaking, you'll need to replace it with a new one.

Before replacing the T&P valve you’ll need to drain your hot water tank. If you’re unfamiliar with how to do this, read Water Heater Maintenance: How to maintain your water heater

  • You won't need to completely empty the tank, just make sure that the water level is below the valve. To check this, simply open the valve. If no water comes out, then the water level is below the valve.

Once your hot water tank has been drained, go to a sink or bathtub and open the faucet on the hot water side. This will let air into the tank. Then, grab the T&P valve with a pair of channel locks and turn it counter clockwise until the valve comes off.

Wrap the threads of the new T&P valve with Teflon tape. This will help seal the valve and prevent future leaking. Be sure to wrap the Teflon tape tightly and work it into the grooves. About 4 or 5 wraps should do the trick. 

With a pair of channel locks, screw the new valve into the water heater until it's securely in place. Then, turn the cold water supply back ON and allow the hot water tank to refill with water.

  • Do not turn the power to the heater back ON until the tank is full

When water begins to flow at a full stream from your open sink or bathtub faucet, the tank is full, and it's safe to turn the power to the water heater ON again.

Remember to attach a discharge pipe to the new T&P valve. This will ensure that any hot water that's release by the valve will go down to the floor, instead of spraying outward.

Temperature & Pressure Valve

How to Replace a T&P Valve
Other T&P Valve Leaks

If you notice that the water is leaking from the threads of your T&P valve then there might be a bigger problem. Follow the instructions above to remove the valve, then check for signs of rust or corrosion on the tank. 

If there's any rust or corrosion, your water heater will need to be replaced. If the tank appears to be in good condition, wrap the threads of the T&P valve in Teflon tape and screw it back in to the tank. Observe your water heater for a period of time to see if this solves the problem.

Another cause of a leak from the T&P valve could be high water pressure in the municipal system or some sort of backflow preventer around the water meter or main shutoff. If you remove your T&P valve and see no signs of corrosion inside the valve it's possible this is your problem. You’ll need a licensed plumber to diagnose and handle these problems.

  • WARNING: NEVER plug the temperature &pressure relief valve to stop a leak. This valve is an important safety feature on your water heater. Plugging the valve will void all warranties on your water heater. But, more importantly, it could cause your water heater to explode!

Drain Valve Leaks

When a drain valve leaks it is generally one of two things. It could be caused by debris inside the valve or the valve itself may be faulty.

Place a bucket under the valve and turn the dial counter clockwise to open the valve.  As the water flows out of the water heater, it should also flush out debris. If it's still leaking after flushing, the valve is faulty and it'll need to be replaced. 

The tank will need to be completely drained in order to replace the drain valve. Follow the same steps outlined above for replacing the T&P valve to drain the tank.

If it's been awhile since you've flushed your water heater tank, it's possible that your drain valve will clog. In which case, you'll need to address the clog first.

  • Unlike the T&P valve, the heater drain valve is not a safety feature. If you're unsure about replacing the valve yourself or don’t have time to get to it right away, simply buy a brass garden hose end cap and screw it onto the valve threads. This should stop the leak until you're able to address the drain valve.
Drain Valve

Internal Tank Leaks

If your water heater is leaking from the bottom of the tank it suggests that there's a serious internal problem. Do NOT attempt to disassemble your water heater and perform internal repairs.

Internal tank leaks can not be repaired and the water heater will need to be replaced. If you are unsure that this is your problem, you should call a licensed plumber.

When Repairs Don't Resolve a Water Heater Leak

A leaking water heater can be a symptom to a more serious problem, so it's important to always keep a close eye on your heater after performing any repairs. If after attempting to fix the problem your water heater is still leaking, turn OFF the power and cold water supply and contact a professional plumber. 

What to Do When Your Water Heater Leaks