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How to fix a water heater relief valve leak

We'll confirm the leak is from the T&P valve, test it, replace it if faulty, and tell you when to call a plumber.

Troubleshooting · Home plumbing
30–60 min
What you'll need
  • Replacement T&P valve (match pressure and temperature rating—typically 150 psi / 210°F)
  • Pipe wrench (and second wrench to hold the tank fitting)
  • Pipe tape (Teflon)
  • Bucket and garden hose (for draining)
Step 1 of 7

Quick triage — pick your path

Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Confirm the leak is from the T&P valve, test it, replace if faulty, and know when to call a plumber.

  • Dry the area around the water heater. The T&P valve is on the top or side with a metal lever and discharge pipe.
  • Good: Water drips from the valve or discharge pipe only—not from the drain valve, connections, or tank. Proceed to Confirm leak.
  • Bad: Water on the tank surface, rust, or wet spots—tank is leaking. Call a plumber immediately. See When to get help.

Confirm leak

Goal: Verify the leak is from the T&P valve and check whether it is occasional or constant.

  • Watch for 10–15 minutes after a heating cycle. Occasional drips can be normal. Constant dripping or steady flow means the valve is faulty.
  • Good: Constant dripping—proceed to Test the valve.
  • Bad: Occasional only—may be normal; monitor. If it increases, return to this guide.

Test the valve

Goal: Test the T&P valve and check the discharge pipe.

  • Shut off power (electric) or gas (gas unit) and the water supply. Open a hot faucet to relieve pressure.
  • Lift the lever on the T&P valve briefly. Water should discharge from the discharge pipe and stop when you release it.
  • Good: Water continues dripping after release, or no water discharges—valve is faulty or discharge pipe is blocked. Proceed to Replace the valve or clear the pipe.
  • Bad: Water discharges and stops—valve mechanism works; if it still drips, replace the valve or check for overpressure.

Replace the valve

Goal: Remove the faulty valve and install a matching replacement.

  • Drain the tank to below the valve level. Unscrew the old valve with a pipe wrench—use a second wrench to hold the tank fitting.
  • Install a new valve with the same pressure rating (typically 150 psi) and temperature rating (typically 210°F). Wrap threads with pipe tape, thread in by hand, then snug with a wrench.
  • Refill the tank and restore power or gas. Watch for 30 minutes.
  • Good: No drips. The repair is complete.
  • Bad: Still drips—check thermostat (120°F), consider expansion tank for closed systems, or call a plumber.

When to get help

Call a plumber if:

  • The tank itself is leaking (water on tank surface, rust, wet spots). The tank cannot be repaired.
  • The valve still drips after replacement.
  • The discharge pipe is blocked and you cannot clear it safely.
  • You have a gas water heater and are not comfortable.
  • You suspect overpressure and need an expansion tank.

Never cap or block the discharge pipe—the T&P valve is a safety device. For other water heater issues, see Fix a water heater that has no hot water or How to fix a water heater leak.

Verification

  • No water drips from the T&P valve or discharge pipe when the tank is full and heated.
  • The valve passes the lever test: water discharges when lifted, stops when released.
  • The discharge pipe runs to a drain or outside and is not blocked.
  • Thermostat is set to 120°F.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm leak location Verify the leak is from the T&P valve, not the drain valve, connections, or tank.
  2. Test the valve Lift the lever briefly; water should discharge and stop. Constant drip or no flow means faulty or blocked.
  3. Replace the valve Drain the tank, remove the old valve, install a matching replacement.
  4. Check pressure and temperature Thermostat at 120°F; expansion tank may be needed for closed systems.
  5. Call a plumber Tank leaking, valve still drips after replacement, blocked discharge pipe, or not comfortable.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether the leak is from the T&P valve, drain valve, connections, or tank
  • Whether the leak is occasional (normal) or constant (faulty)
  • Valve test result (water discharges and stops, or continues dripping)
  • Discharge pipe condition (clear or blocked)
  • Steps already tried

Is the leak from the T&P valve?

The T&P valve is on the top or side with a lever and discharge pipe. The drain valve is at the bottom. Tank leaks show water on the tank surface.

Dry the area and watch where water appears. T&P valve: water at the valve body or discharge pipe. Drain valve: water at the bottom. Tank: water on tank surface, rust, wet spots. Good: leak is at T&P valve—proceed. Bad: tank leaking—call a plumber immediately. Drain valve or connections—see how-to-fix-water-heater-leak.

Yes No (tank or other)

You can change your answer later.

Is the leak occasional or constant?

Occasional drips after heating can be normal. Constant dripping means the valve is faulty.

Watch for 10–15 minutes after a heating cycle. Occasional: brief drip after heating—may be normal. Constant: steady drip or flow—valve is faulty. Good: constant drip—proceed to test. Bad: occasional only—may not need repair; monitor.

Constant Occasional

You can change your answer later.

Monitor or proceed

Occasional drips can be normal. If it increases or becomes constant, return to this guide. Check thermostat is at 120°F. If you want to test the valve anyway, proceed to Test the valve.

Done

Does the valve pass the lever test?

Lift the lever briefly. Water should discharge and stop when released.

Shut off power and water. Lift the T&P valve lever briefly. Pass: water discharges, stops when released. Fail: water continues dripping, or no water discharges (blocked). Good: fails—replace valve. Bad: passes but still drips—check discharge pipe or replace valve.

Yes (fails) No (passes)

You can change your answer later.

Is the discharge pipe clear?

Blocked discharge pipes can cause pressure buildup and dripping.

Check the discharge pipe runs to a drain or outside and is not blocked. If blocked, clear it. If you cannot clear it safely, call a plumber. Good: pipe clear—valve may need replacement anyway if it drips. Bad: blocked and cannot clear—call a plumber.

Yes No (blocked)

You can change your answer later.

Replace the valve

Drain the tank below the valve. Remove the old valve with a pipe wrench. Install a matching replacement (150 psi / 210°F typical). Refill and test. Good: no more drips. Bad: still drips—check thermostat (120°F), expansion tank, or call a plumber.

Done

Call a plumber

Call a plumber if: the tank is leaking; the valve still drips after replacement; the discharge pipe is blocked and you cannot clear it; you have a gas water heater and are not comfortable; or you need an expansion tank for overpressure. Never cap the discharge pipe.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why does my water heater relief valve leak?
Common causes: mineral buildup, a worn or stuck valve seat, overpressure from thermal expansion (no expansion tank), or a thermostat set too high. An occasional drip after heating is normal; constant dripping means the valve needs replacement.
Is it normal for a T&P valve to drip occasionally?
Yes. A brief drip or small amount of water after a heating cycle can be normal pressure release. Constant dripping, steady flow, or water running down the discharge pipe means the valve is faulty and should be replaced.
When should I call a plumber for a relief valve leak?
Call a plumber if the tank itself is leaking, the valve still drips after replacement, you have a gas water heater and are not comfortable, or the discharge pipe is blocked and you cannot clear it safely. Do not cap or block the discharge pipe—the valve is a safety device.

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