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Why Is Water Leaking From the Bottom of My Water Heater?

Fact checked by Stephen Conklin

why is water leaking from-the-bottom of my water heater

Are you asking yourself, why is water leaking from the bottom of my water heater? Water heater leaks can develop due to various reasons. Knowing what causes the problem will help you determine the next best course of action.

In this article, we will look at three possible causes of water leaks from the bottom of a water heater. We will also discuss ways you can address the issues. Hopefully, it’ll help you in choosing what to do next.

Table of Contents

Issue 1: A Broken Drain Valve Can Cause Leaks at the Bottom of the Water Heater

A broken or damaged drain valve is the most obvious reason for a water heater leaking from the bottom. After all, it is a water heater component you can find at the bottom of the tank.

Things to know about the drain valve

The drain valve lets you empty the hot water tank’s contents to facilitate a more comprehensive removal of sediments and debris during regular maintenance. It also promotes more efficient flushing, replenishing the tank with fresh and clean water.

Unfortunately, frequent drain valve manipulation can lead to loose threads, giving the water sufficient space to leak through. Rust or corrosion can also undermine drain valve integrity, causing it to leak. The phenomenon is most common in households with high iron content in the water.

While iron is beneficial to human blood cells, it can wreak havoc on metal objects because of the resulting oxidation reaction. Corrosion can weaken the metal object’s structural integrity, causing leaks in the case of a water heater.

What should we do with the drain valve?

It would be best to assess the hot water tank’s drain valve and check for signs of corrosion or any other surface abnormality. Try tightening the drain valve knob by turning it counterclockwise as far as you can go. It is possible someone accidentally hit the valve knob, opening it a bit and causing a small leak.

If the tank continues to leak after tightening the drain valve knob, you might already have a broken drain valve you must replace.

The good news is you can fix this:

  • You can install a garden hose cap into the drain valve to stop the water heater from dripping from bottom.
  • You can replace the faulty drain valve with a new one during your next water heater draining routine.
  • If you already placed a hose cap into the valve and the tank bottom still leaks, it can only mean that the drain valve is not watertight. You can expect the leak to get worse. As such, it would be best to replace the drain valve altogether.
  • It would also be wise to place a water sensor alarm or water leak alarm under the hot water tank drain valve. This device will alert you of future leaks from your water heater.

Issue 2: A Faulty Temperature and Pressure (T&P) Relief Valve Can Also Cause Leaks


Things to know about T&P valve

If the drain valve is intact or you have already replaced it, yet the issue of the leaking water heater is still there, you might want to check the temperature and pressure (T&P) relief valve.

The T&P valve is a crucial component of any hot water tank. This valve allows the tank to reduce excess pressure and water due to thermal expansion. Heating the water causes it to expand. Unfortunately, the hot water tank is a closed system, increasing pressure buildup inside the tank.

You can expect your hot water tank to start expanding as the water reaches a temperature of 120 to 140 degrees Fahrenheit. If the temperature rises, thermal expansion can further increase intra-tank pressure, damaging the hot water tank.

A T&P relief valve automatically vents out hot water and steam to reduce pressure and temperature. Most products automatically open the T&P valve at a water pressure of 150 psi or a temperature of 200 degrees Fahrenheit.

The hot water tank has a discharge tube connecting to the T&P valve on one end and emptying it onto the floor on the other end. Every time the T&P valve opens, it releases excess hot water and steam into the discharge tube.

Ideally, you should not see a puddle of water at the floor end of the discharge tube. The water will be so hot that it evaporates upon leaving the T&P valve.

What should we do?

  • It would be wise to check the discharge tube’s open end if you see water leaking from the bottom of water heater. The T&P valve may be faulty, opening even though the hot water tank’s inside pressure and temperature are within normal limits.
  • Unfortunately, a normally functioning T&P valve can still cause water leaks. It happens because of a defective thermostat, causing the device to heat the water beyond its rated temperature. Increasing the water temperature also increases pressure, opening the T&P valve.
  • The T&P valve is a critical component of your water heater. It would be best to call a licensed plumber to check your unit if you suspect the T&P valve is the reason why your water heater leaks from the bottom.

Issue 3: Damage to the Hot Water Tank Requires Your Immediate Attention


If neither a faulty drain valve nor a problematic T&P relief valve is causing your water heater to leak from the bottom, the issue might be the tank itself.

Things to know about the water heater tank

Hot water tanks have a steel or metal construction, such as copper, stainless steel, and carbon steel. Some products have an inner lining of vitreous enamel, glass, or plastic to protect the metal surface against corrosion.

Unfortunately, even with these protections, the hot water tank’s inside surface can still accumulate with sediments, particles, and other compounds that can eat through the layers. These substances can react with other chemicals to corrode the unprotected metal surface.

Experts recommend flushing the hot water tank at least every two months and draining it at least every six months. Draining the hot water tank allows you to remove sediment, debris, and particles that may have accumulated in the tank.

Failure to flush and drain the water heater regularly can lead to internal tank corrosion, cracking, and other structural damage. Continued neglect can worsen the structural issue.

Combined with constant contact with hot water and excessive water pressure, these weakened areas can give in over time. When it does, you now have an exit point for hot water to leak through.

Hence, a leaking water heater from the bottom of the tank might already be a sign of loss of tank integrity.

What should we do?

Sadly, the only solution is to replace the water heater. You might also want to consider getting a tankless water heater instead.


There are three potential answers to the question, why is water leaking from the bottom of my water heater?

  • A faulty or leaky drain valve
  • A problematic temperature and pressure relief valve
  • An internal tank leak due to corrosion secondary to sediment buildup

Other reasons can potentially lead to water heater leaks. However, these three causes are the most common ones. Starting with these issues first makes perfect sense.

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