Water Heater Leaking from Relief Valve? Here’s What It Means and What to Do

If you’ve noticed water pooling around the base of your water heater or dripping from a pipe on the side, you may have a water heater leaking from the relief valve, and it’s not something to ignore. This valve, while small, plays a big role in your safety. When it leaks, it could be a simple pressure issue or a sign of a much bigger problem.

In this guide, we’ll break down why your temperature and pressure relief valve (T&P valve) might be leaking, what to do about it, and when it’s time to call in a professional.

Table of Contents

What Is the T&P Relief Valve on a Water Heater?

The temperature and pressure relief valve, also called a T&P valve, is a safety feature found on every modern water heater. It’s typically located on the top or side of the tank and is connected to a discharge pipe that extends toward the floor.

Its job? To release water if:

The temperature gets too high (above 210°F)
The pressure inside the tank exceeds safe limits (over 150 psi)

In either case, the valve opens automatically to prevent the water heater from exploding due to excessive pressure. So, if your relief valve is leaking, there’s a reason.

Why Is My Water Heater Relief Valve Leaking?

There are several possible reasons, ranging from minor to serious:

1. Normal Operation

Sometimes the valve opens momentarily to relieve minor excess pressure, especially after a hot shower or during heavy water usage. A few drops of water may appear at the end of the discharge pipe. This is not necessarily a problem if it stops quickly.

2. High Water Pressure

If your home’s water pressure exceeds 80 psi, it can cause the T&P valve to release water more frequently. Installing a pressure-reducing valve (PRV) on your main water line can help regulate pressure.

3. Thermal Expansion

When water heats up, it expands. If your plumbing system is closed (meaning it doesn’t allow water to flow back into the main supply), that extra pressure has nowhere to go, except out the relief valve. In this case, installing an expansion tank is recommended.

4. Faulty T&P Valve

Over time, the valve itself may wear out, corrode, or become blocked with sediment. In this case, the leak is not due to pressure or heat, it’s a failing valve that needs replacement.

5. Water Temperature Is Too High

If your water heater is set above 140°F, it may regularly trigger the valve. Check your thermostat settings and lower the temperature if needed.

6. Sediment Buildup or Tank Failure

In older water heaters, sediment buildup inside the tank can lead to overheating or corrosion, increasing pressure and triggering leaks. If the tank is rusted or cracked, you’ll likely need to replace the entire unit.

Is a Leaking Relief Valve Dangerous?

Yes, potentially.

A leaking T&P valve can be a warning sign of serious pressure buildup or overheating. Ignoring it could lead to:

Flooding and water damage
Scalding if hot water leaks suddenly
Catastrophic tank failure (rare, but possible if pressure continues to rise unchecked)

Don’t assume a leak is minor, always investigate further.

How to Check If the Valve Is Working

You can test the valve by carefully lifting the metal tab or lever on top of the valve:

Stand back (hot water may spray).
Lift the lever for a few seconds, water should flow freely.
Release it, water should stop.

If the valve continues to leak after this test, or no water comes out, it’s likely faulty and needs to be replaced.

Caution: Only do this test if you feel confident and safe. Wear gloves and eye protection. If unsure, call a plumber.

What to Do If the Relief Valve Is Leaking

Here’s what to do based on your situation:

Step 1: Identify the Leak Source

Is it dripping from the discharge pipe only?
Is water seeping from the valve threads or around the fitting?

Step 2: Check the Temperature and Pressure

Temperature should be set between 120–140°F.
Water pressure in your home should be below 80 psi.

Use a water pressure gauge (available at hardware stores) to test a faucet or hose bib.

Step 3: Replace the Valve (If Faulty)

If the valve is old or corroded, replacing it is straightforward:

Turn off water supply and power to the heater.
Drain the tank below the valve level.
Unscrew and remove the old valve.
Wrap new Teflon tape around threads.
Install the new valve and test.

This is a DIY-friendly task for handy homeowners, but always shut off utilities first.

Step 4: Install an Expansion Tank (If Needed)

If you’re seeing regular leaks due to thermal expansion, a small expansion tank installed near the water heater will absorb pressure changes, preventing valve discharge.

When to Call a Plumber

Call a professional if:

The leak continues after replacing the valve.
The tank itself is corroded or leaking.
You’re unsure whether it’s pressure, temperature, or structural failure.
You suspect your home’s plumbing lacks a pressure regulator or expansion control.

Preventing Future Leaks

Keep your water heater temperature between 120–130°F
Flush the tank annually to reduce sediment buildup
Install a PRV if your water pressure is too high
Add an expansion tank if you have a closed system
Inspect the T&P valve yearly for signs of rust or wear

Final Thoughts

A water heater leaking from the relief valve might seem like a minor inconvenience, but it’s your system’s way of alerting you to pressure, temperature, or internal issues. Whether it’s a simple valve swap or a sign of deeper problems, taking action early protects your home, your safety, and your hot water supply.

If you’re unsure where to start or need help diagnosing the problem, I can walk you through a custom checklist, or help you decide whether it’s time for a new water heater. Just ask!