Water Heater Leaking: What should you do?

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 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.

Water heater leaking can also 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.

A water heater leak does not shrink or go away with time. It only gets worse, so it’s best to move quickly to fix the problem.

Water Heater Leaking Step 1: Determine whether your water heater is the source of the leak

Not every small puddle of water found at the base of a water heater is necessarily due to a leak. A water heater and the pipes around 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, wipe it up and try to determine its source through simple observation. Closely inspect 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, lay down some paper towels over the area that was damp and come back to check on it every few hours. If, after a day or so, the problem does not re-appear, it’s likely nothing to be concerned about. If, however, water does show up again and no other source for it can be readily identified, the water heater leaking is the likely cause, and the inspection steps that follow should be carried out

Water Heater Leaking Step 2: Turn off the power to your water heater

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.

Water Heater Leaking Step 3: Turn off the water supply

WARNING: Water heaters are typically factory-set to heat water to 125° F, 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 160ºF to 190º F) serious injuries can result from even indirect contact with the water. Always take precautions to avoid coming into contact with heated water.

If the water heater leaking is significant and obvious, turn off the water supply at the cold water shut-off valve.

Most water heaters will a valve located above the water heater (by code they are required to be here) that will shut off the water supply. This valve will either have a handle that you have to pull down, or a gate valve (essentially a dial) that you will have to turn clockwise to close. Before closing the valve, make sure you can get to it safely without coming in contact with any water. If you have a large, serious leak and cannot reach the water shut-off valve safely then you should find the main shut-off valve for the house and close it to stop the water supply to your water heater. Shutting the water off should slow and may even stop the leak depending on where it is coming from.

If the actual leak source is not yet identified, leave the water supply on for the time being, to assist in locating it.

Water Heater Leaking Step 4: Determine the location of the leak

There are a number of problems that can cause water heater leaking, so it’s a good idea to perform a quick inspection. A proper diagnosis of the leak before calling a professional will make it easier for them to solve the problem.

  1. The cold water inlet and the hot water outlet connections: Check the points at which the inlet and the 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 and is likely very fixable.
  2. The temperature and pressure relief valveEvery water heater has a temperature and pressure relief valve located on the side of the tank with a pipe running down to the floor. This valve is in place so that in the event that the water is heated too much, or there is too much pressure in the tank, the valve will let water out of the tank to relieve pressure. Inspect the point at which it enters the tank, on the side of the water heater near the top, to see that it is watertight. Also inspect the valve itself. If this is the source of the leak, then water will be flowing down the plastic pipe attached to it when the valve is in the closed position. This means that either the valve is defective, or it is working properly and excess pressure inside the tank is forcing it to open. A leak from this location is usually fixable, but is also cause for concern.
  3. The heater drain valveCheck the drain valve, located near the bottom of the tank. Make sure that it closes (and is closed) completely, and that its point of entry into the tank is watertight. A leak from this location is not a serious problem and can be fixed.
  4. The bottom of the hot water tankSince the tank itself is wrapped inside insulation and is enclosed in an outer skin, any leak in it will not be visible from the outside. If your water heater has an internal leak water will likely escape at the bottom of the tank. Most water heater leaks are from the tank itself, and are due to age and deterioration. If this is the case the only fix is to replace the water heater.

Water Heater Leaking Step 5: Repairing or replacing

As stated above, water heater leaking can be a serious problem, so take action quickly. Depending on the type of leak you have, you will either have to repair your water heater, or replace it. In both cases, it is 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 much more serious problems. A professional plumber will be able to take care of any issue your water heater has.

Water Heater Leaking: How to fix a leaking water heater

Water Heater LeakingIf 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. 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 much more serious problems. If you do not have any experience doing home plumbing repair it is highly recommended that you call a professional plumber to deal with the problem.

Is your water heater leaking from the cold water inlet and the hot water outlet connections?

Check the points at which the inlet and the 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 than that will require a professional repair.

Is your water heater leaking from the temperature and pressure relief valve?

A leak from the temperature and pressure relief valve (T&P valve for short) 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 water heater leaking. To see if this is what’s causing the leak, reduce the temperature of the water by lowering the thermostat setting. 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.

If you determine excessive pressure or overheating is not causing the problem, then you may have a faulty valve. Put a bucket or container under the discharge tube and open the T&P valve by pulling the tab on the valve up so it’s pointing straight out. This will flush the valve out and remove any debris that may be causing it to work improperly. If after flushing the valve it is still leaking you will need to replace it.

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. There’s no need to empty the tank completely. Just ensure 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 your sink or bathtub and open the faucet on the hot water side to 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. Take your new valve and wrap the threads with Teflon tape four or five times (this will help seal it against any leaks). Make sure you wrap it tightly and work the tape right into the grooves. After this is done, screw the new valve into the water heater, using the channel locks to turn it three or four times until it is securely in place.

Once the new valve is in place you can turn on the cold water supply to refill the hot water tank with water. Do not turn the power to the heater back on until the tank is full. Check the sink or bathtub faucet you previously opened. When water is coming out of it at full stream you know your tank is full and you can turn the power back on.

Make sure to attach a discharge tub to your new T&P valve. This ensures that any hot water released by the valve goes down to the floor and does not spray outward.

Still have question about how to replace the T&P valve? Try watching this video:


Other Possibilities: If water is leaking from the threads of your T&P valve then remove the valve as per the instructions above. Check for any rust or corrosion on the tank. If there is 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 valve in Teflon tape and screw it back on 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 then this may be the case. You’ll need a licensed plumber to diagnose and handle these problems.

Warning: NEVER plug the temperature and pressure relief valve to stop a leak. This valve is an important safety feature on your water heater. Plugging the valve will void any warranties your water heater has. More importantly, it could cause your water heater to explode.

Is your water heater leaking from the heater drain valve?

A leak from the heater drain valve may be caused by debris inside the valve or a faulty valve (similar to the T&P valve). Place a bucket or container under the valve and turn the dial counter clockwise to open the valve. This should flush out any debris. If after flushing the valve it is still leaking you will need to replace it.

To replace the drain valve, drain the tank completely and follow the same steps outlined above for replacing the T&P valve.

Tip: Unlike the T&P valve, the heater drain valve is not a safety feature. If you are 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.

Is your water heater leaking from the bottom of the tank?

This suggests a serious internal problem and it is likely your water heater needs to be replaced. Do not attempt to disassemble your water heater and perform internal repairs. If your water heater is leaking from the tank either call a licensed plumber to inspect it further or replace the water heater.

Is your water heater still leaking after repairs?

Water heater leaking can be the symptom of a more serious problem, so keep a very close eye on your water heater after performing any repairs. If after attempting to fix the problem there is still a leak shut the power and cold water supply to your water heater off immediately and call a professional plumber.

photo credit: Rob Ireton via photopin cc