Why Is My Water Heater Leaking?

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Whether you depend on a gas or electric water heater to provide you with calming hot showers or baths, as well as provide your washing machine with water hot enough to successfully clean your clothes, you want to make sure that water stays in the water heater tank until it’s needed… and not leaking onto the basement or laundry room floor. If you’re seeing a puddle forming around the base of the water heater and you don’t know why, Repair Clinic has some answers for you.

Following a water heater’s water trail

Gas water heaters will use either a pilot or a hot surface ignition system to ignite a burner positioned directly under the bottom of the tank to heat the water. Most electric water heaters use two electric heating elements to warm the water in the tank. But how the water enters the tank and how that water can leak out is the same regardless of the water heater model.

A dip tube ensures all the water in the tank is heated thoroughly

Water from the home’s main water supply line enters the water heater through the incoming cold water pipe and into a dip tube secured within the tank. The dip tube distributes the incoming water to the bottom of the tank to ensure that all of the water is heated evenly. If the dip tube deteriorates and breaks the incoming water will stay near the top of the tank where it won’t heat properly. Once heated, the water travels through the outgoing hot water pipe to your home’s bathrooms, kitchen, and laundry room.

A dielectric union is needed to avoid electrolytic corrosion

Both the incoming cold water pipe and the outgoing hot water pipe connect to galvanized steel pipes on the tank. Since many homes have copper plumbing, a dielectric union is needed to connect the two types of piping. Without this union, the pipes can deteriorate due to electrolytic corrosion, a process that occurs when water flows across two dissimilar metals. If your home has copper plumbing, but your water heater does not have a dielectric union, that water leak could be caused by the deterioration of the pipe connections directly above the unit.

An anode rod is used to attract corrosive minerals

While water heater tanks are traditionally metallic, the interior of the tank is coated with enamel to help prevent chemicals, salt, and other minerals from corroding the metal. As an additional safety precaution, an anode rod is used within the tank to attract corrosive minerals. Some water sources, such as well water, will attack the anode rod which can result in a strong sulfur smell. However, removing the anode rod is not recommended since the corrosive minerals the rod attracts can quickly deteriorate the tank resulting in a leak.

Water flow is controlled by three valves

Most water heaters will have three valves to control the water flow: a shut-off valve attached to the incoming cold water pipe, a drain valve near the bottom of the tank, and a temperature and pressure relief valve near the top. The shut-off valve is primarily used to stop water from entering the tank when repairs are required (replacing a heating element, for example, or another valve). You will also need to close this valve when flushing out old water from the tank.

As we’ve already discussed, mineral deposits can collect in the tank over time. To avoid deposit build-up, the drain valve can be opened to flush out old water that contains these mineral deposits. How often should this be done? Repair Clinic recommends flushing out all of the water from the tank once every few years. However, if your home uses well water (which contains more minerals than a municipal water supply), you may want to do this more frequently.

When water is supposed to spill out of a water heater

The third valve can actually be responsible for that alarming puddle of water you’re seeing in front of your water heater. If the water temperature or pressure increases above proper operating levels, the temperature and pressure relief valve will automatically open to release both steam and water to stabilize the system. A discharge tube is required to be installed on the valve with its open end positioned six inches from the floor to direct the released steam and water downward. This will prevent injury from scalding steam and water spraying outward but it can also give the impression the water heater is leaking. If you find that water is repeatedly being released through the temperature and pressure relief valve, the unit’s water temperature selection dial may be set too high or a thermostat may be malfunctioning.

Three more reasons why your water heater is leaking

So, you’ve confirmed your water heater uses a dielectric union to connect the home’s copper plumbing to the tank’s galvanized steel pipes and the water temperature/pressure is at a proper operating level. Could there be something else causing the leaking problem? Yes, there are three more reasons why your water heater may be leaking:

  1. Defective temperature and pressure relief valve – Remember that valve that automatically opens to release steam and water to stabilize an overheated water heater? Well, that valve can fail and continue to release water even when the water temperature or pressure is not excessive. You can fix this problem by replacing the defective valve with a new one. It’s just like replacing a light bulb: use a pipe wrench to both remove the discharge tube from the valve and to rotate the old valve counter-clockwise to unthread it from the tank (close the shut-off valve and drain about a third of the water from the tank before doing the repair). Next, apply thread sealant to the threads of the new valve and use the wrench to rotate the valve clockwise to install it. Reattach the discharge tube and reopen the incoming water valve.
  2. Malfunctioning drain valve – Yes, the drain valve can malfunction as well and develop a leak. You can fix the problem by installing a new drain valve in the same manner as a temperature and pressure relief valve, but you will need to completely drain the water heater first since the drain valve is located near the bottom of the tank.
  3. Rusted tank – Despite the use of an anode rod to attract corrosive minerals and the enamel coating to protect the inside of the tank, over time a water heater tank can still rust and begin leaking. There’s nothing you can do to successfully repair a rusting tank, so Repair Clinic recommends reviewing the product’s warranty to see what’s covered and for how long before you purchase a new water heater.
Electric Water Heater Leaking?

Water heater repair resources from Repair Clinic

As your repair partner, Repair Clinic wants to make sure you’ve got access to the resources you need to fix a water heater yourself. Our “Videos & Articles” content library provides free instructional videos such as this one showing the correct way to install a new temperature and pressure relief valve on an A.O. Smith gas water heater (Model GCV40200). You can also find model-specific schematics, diagrams, and step-by-step repair guides for all of your home’s heating and cooling units in addition to all major home appliances and outdoor power equipment.

Finding genuine OEM water heater parts

Repair Clinic takes the stress out of finding the genuine OEM replacement part to fix your water heater. Whether you need to repair a Rheem, A.O. Smith, Bradford White, Bryant, Carrier, Coleman, Honeywell, or Lennox product, all you have to do is enter the full model number of the unit in Repair Clinic’s search bar to see a complete list of OEM parts fully compatible with that model. You can then use the “Part Category” and “Part Title” navigation filters to identify the exact part you’re looking for.

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