Why Is My Water Heater Leaking?

Have you found your water heater leaking? It can be worrying to see and often can be attributed to your water heater behaving less efficiently then it once did. You might be noticing that your water is not as hot as is should be or that you have no hot water at all, as many people do, and this can be the result of the water heater leaking.

A water heater can leak from different places in different ways and it’s important to find out where the leak is coming from to discover whether you are in need of some water heater repairs or whether there is a simple quick fix.

There could be a vast array of problems that’s either causing or caused by the leak, such as a loose T&P valve or damage to the tank. On the other hand, water pooling may not be caused by the water heater leaking but may just be the result of condensation.

This article is for those who have noticed their water heater leaking and don’t know what it means. We’re going to take you through the different types of leaks and how they can affect your water heater, if they do at all. Don’t forget to use the contents table below to navigate this article to find the type of leak you are experiencing and what can be done about it.

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

Is It Dangerous To Have a Leaking Water Heater?

The first thoughts that run through your mind when you notice the leak may well be “Is my water heater leaking dangerous?” and nobody could blame you for asking! Water leaks in general can be quite dangerous as they can cause damage to property, particularly electricals, causing them to short circuit and become hazardous.

The main cause for concern with a hot water heater is the potential for it to explode resulting in damage to you, those around you and your property. A water heater explosion can occur if there is an extreme build up of water pressure within the device and its associated pipes and valves.

There’s also an often overlooked hazard, and that’s the dispersal of microbes or rust throughout the household water supply. 

This can be caused by a leak

which is the result of a rusty pipe allowing rust and pathogens to contaminate your water system.

So to answer your question: yes, a leaking hot water heater can be dangerous and is not a situation to take lightly. Even though explosions are not common place, if you are ever unsure about the state of your water heater and notice a dangerous pressure build up, it’s safer to get a professional plumber to diagnose and perform repairs or replacements.

Water Heater Leaking From the Top

If you have found a leak coming from the top of your water heater you are more fortunate than those who found one at the bottom. A top leak is much easier and cheaper to diagnose and repair.

The following are some of the various common reasons of why a leak may be coming from the top of your water heater:

How exactly do you determine which of these is the cause of the water heater leaking from the top? We’re going to teach you how to take a look for yourself and find out exactly what’s causing your hot water heater leak!

#1 Turn The Water Heater Off

This means shutting off the water supply to your hot water heater from the dedicated valve which is usually located near your main water supply valve.

If you have a gas water heater you should also shut off the gas supply to it via the the valve on your gas supply piping labelled water heater. Make sure that the lever is turned at a 90 degree angle perpendicular to the pipe to ensure it is fully closed.

Note that when it comes to starting the gas water heater up again, you will need to reignite the pilot light. If it has auto-ignition, you’ll be able to do this with a simple push of a button but if there is no auto-ignite you will have to refer to the manufacturer’s instructions to reignite the pilot light manually.

If you have an electric water heater switch off the electricity supply form the main switchboard. Simply flick the switch labelled “water heater” into the “off” position.

When it comes to starting the electric heater back up again, it is best to allow the water tank to refill before switching the electrics back on. You could damage the heating elements if you do not allow the electric water heater tank to refill before switching it back on.

#2 Dry Out The Water Heater

Using absorbent paper towels, try to dry up as much moisture as you can. Be sure to get around all the pipes, cracks and crevices in the area maybe leaving it the towels for a while to absorb all the moisture possible.

Removing all of the previously existing moisture will allow you to get a better view of where the leak is coming from when you get to turning the water heater back on again.

#3 Identify Where the Leak is Coming From

After turning your water heater back on again you will need to be keenly observant for any appearances of moisture, trails of water and dripping from pipes. It can be difficult to notice sometimes, but persevere and you will be able to find out where the leak is coming from.

Check the cold water inlet valve which sits just above your heater and will have a lever. It may also have “cold water inlet” marked on the lever handle. If the leak is coming from this valve, it may just be a case of it needing tightening.

Check all connections between pipes. On the very top of your water heater sit the hot and cold water pipe connections, check for signs of leaking such as rust or a white, powdery deposit. These may just need tightening or may need replacing.

Sometimes found on the top of the heater and sometimes on the side is the temperature and pressure release  valve or T&P Valve. It can leak water from its top or from the screws which attach it to your water heater. Check for damage also. It may also just need tightening or replacing.

Be aware that the T&P Valve can also be found on the bottom of the leaking hot water heater.

The water heater leaking may be coming from the water tank itself.

If this is the case, it may mean that the tank is damaged from corrosion or rust. Unfortunately there is no way to fix this and the tank will need replacing if you want to restore your water heater to working condition.

Your heater may have an expansion tank fitted either above it or within it. Check the expansion tank, the fittings and the connections surrounding it for leaks. If the tank is leaking you will need to replace it but if the leak is coming from any of the connections, they may only need tightening.

You water heater contains an anode rod to attract particulates in the water. The port for the anode rod is on the top of your water heater. If the anode rod has not been replaced for a long time it can become corroded over time and lead to leaking through the port. If this is so, it may be a simple case of replacing your anode rod.

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

Water Heater Leaking From the Bottom

A leak coming from the bottom of your water heater can be a bit easier to diagnose as there are less places that its coming from. Unfortunately this is not a good thing because 1 out of 2 of these components will mean the whole water heater will need replacing.

In the case of a water heater leaking from the bottom, the two components that are the likely culprits of the leak are the drain valve and the tank. In some models it could also be the temperature and pressure relief valve if it is located lower down on your water heater.

The way to determine where the leak is coming from is the same process as if the water heater was leaking from the top which is explained above.

#1 Turn The Water Heater Off

#2 Dry Out The Water Heater

#3 Identify Where the Leak is Coming From

If you are sure it is the drainage valve, this can be replaced by a professional plumber quite cheaply. If it is the tank on the other hand, you are looking at replacing the whole water heater, which is unfortunate but sometimes it must be done.

Water Heater Leaking From Drain Valve

The drain valve functions primarily for you to use to intentionally drain water form the tank when you open the faucet. Your water heater should not be leaking from the drain valve of its own accord and this can cause problems.

Use the tests above to determine if it is indeed your drain valve that is leaking, you can also take a cotton swab to it to see if there is dampness around it after drying the area out and switching your water heater back on again.

If it is your drain valve that’s leaking, start by gently tightening it with an adjustable wrench. Don’t tighten it too much because this can cause the leak to become worse. If this does not work you will need to remove the drain valve to inspect it.

To remove the drain valve you must first drain the tank. You will need to connect a hose to the drain valve and run that to a drain elsewhere.

Shut off the power to the water heater at the main circuit breaker, shut off the cold water supply valve and open the water heater relief valve. Once the tank is empty you can remove the drain valve and take a closer look.

Often times, if there is a problem with the drain valve it is usually the washer inside becoming worn from overtime usage. The simplest fix for this is to replace the washer, replace the valve and this may fix the leak. Otherwise it is easiest to just replace the drainage valve.

See the below video for a great tutorial on how to replace a drain valve.

Water Spraying From The Pipes

If what you have spotted is less of a water heater leak and more of a torrent of water gushing from a junction or hole in the piping somewhere, the first port of call is to shut off the water supply at the valve.

If the leak is after the shut off valve to your water heater, it is okay to shut the water off using that valve, but if before, you may need to shut the main water supply off completely.

Unless you know how to perform a temporary repair on the pipes yourself using a pipe repair clamp you are going to need to call out a plumber.

Need help with a repair or install? Get a free estimate online from top local home service pros in your area.

About the Author

Dave Miller is a HVAC technician with over 10 years in the industry. Dave created HeatTalk with the ambition for it to become a resource for individuals looking for answers, whether they be a layman, student or a professional.