If there is water leaking from a water heater, it’s a clear sign of a problem. You’ll need to take immediate action to repair the issue but first, you’ll need to understand what the problem entails. There can be several reasons that a water heater might leak from the bottom.

Usually, the source of water leaking from beneath a water heater can be traced back to the drain valve or the tank lining. In some cases, the water may not be coming from the tank at all. It could be coming from a side panel or the pressure relief valve. Either of these can give the appearance that the source of the water leak is underneath the water heater.

In some cases, the water may not be coming from the water heater at all. Nearby leaks that have puddled beneath the water heater such as those created by damaged pipes can be mistaken for water heater leaks. Check out pipe burst causes for more information.

Assuming that the leak is coming from the water heater, let’s take a look at some possible causes and how to fix the problem.

Reasons A Water Heater May Leak from the Bottom

If you’ve eliminated other possibilities, it’s time to take a look at the water heater. You should first turn off the power to the unit to prevent potential personal injuries. The issue is normally found in one of two places: the drain valve or the tank. Let’s look further at these potential issues.

Drain Valve

You will find the drain valve close to the water heater’s base. A leaky drain valve may be as simple as it has not been secured properly during previous maintenance and is leaking. Check the rubber gasket to see if it is loose and the drain valve itself to see if it is securely fastened.

A drain valve leak will usually involve only a small amount of water on the floor. You may not notice it for a while. In areas where water evaporates quickly, you might only see water stains from where it has leaked and dried. There may also be a bit of water in the water heater pan if you have one, rather than on the floor.

Drain valves may be plastic or brass. Plastic valves have a higher rate of failure because they tend to crack as they age and are easy to damage when you try to remove them. Brass valves hold up better, but Teflon tape must be used on the threading to make sure a tight seal is formed.

If you are seeing a cracked plastic drain valve, don’t see any Teflon tape on a brass valve or if the Teflon tape you are seeing shows signs of deterioration, you’re looking at a fairly simple fix. All you need is a wrench and the replacement parts to correct the problem. If your drain valve is plastic, you can replace it with the same but it is recommended that you switch to a brass valve instead. All you need to do is wrap the threads with the Teflon plumbers’ tape and screw a replacement valve into place.

Tank Lining Corrosion

Sediment building up in the water heater tank can cause corrosion. It can become a much larger problem if left unattended for too long. Without regular water heater inspections, it may be a while before you discover just how much damage has been done.

The best way to prevent this is to flush sediment from your gas or electric water heater tank at least once every year. Failure to do so can result in the erosion of the anode rod. Once this has deteriorated, the sediment will begin eating away at the water heater tank’s liner. This can create tiny leaks at the bottom of the unit where the sediment collects, leaving you no choice but to replace the water heater.

Leaking Pressure Relief Valve

If your temperature and pressure relief valve is leaking, it may lead to water pooling on the floor or in the drain pain from its discharge pipe. This can appear as if the water heater itself is leaking. This relief valve is designed to release the pressure that has built up in the water heater tank. If water is leaking from it, it might signal that your thermostat is set higher than it should or that your thermostat has failed rather than any problem with the valve itself.

In many cases, this kind of excessive pressure is a sign that the water heater should be replaced. If the water heater is older, this may be the case. If the water heater is still in good shape, you may want to add an expansion tank to offset the excess pressure.

If you do have a failed pressure relief valve, you will want to replace it. It’s a simple process similar to replacing the drain valve.

What to Do If Your Tank is Leaking

If you have examined the water heater and either determined that the tank is leaking or have been unable to determine the source of the problem, you will want to take immediate action. First, shut off the main water valve and then turn off the water heater’s electrical supply at the breaker box. Most water heaters are on a circuit by themselves, so this should not affect any other appliances in your home. If you have a gas water heater, you should find the OFF switch on the side of the heater toward the lowered part of the tank.

While you can do without a water heater, it’s not very convenient. Until you have it repaired or replaced, you’ll have to heat any water you need to use, which may not be too much of a problem if washing dishes by hand or doing a cold wash of clothes. However, it is not very pleasant when you need to shower, run the dishwasher or wash clothes in hot water. You’ll want to contact an HVAC professional to examine the water heater as soon as possible and make repairs or replace the unit with a recommended replacement.