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Fix a pressure relief valve that leaks

We'll confirm the leak location, test the valve, rule out blocked pipe and high pressure, and replace the valve if faulty—or tell you when to call a plumber.

Troubleshooting · Home maintenance
30–60 min
What you'll need
  • Pipe wrench
  • Replacement pressure relief valve (match pressure and temperature rating)
  • Pipe thread sealant (Teflon tape or dope)
  • Garden hose and bucket (for draining)
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Steps

Goal: Confirm the leak location, test the valve, rule out blocked pipe and high pressure, and replace the valve if faulty.

  • Dry the area around the water heater or boiler. Confirm water comes from the pressure relief valve or its discharge pipe—not from the tank, boiler, drain valve, or connections.
  • Good: Leak at valve or pipe. Proceed to Shut off power and water.
  • Bad: Tank or boiler is wet or rusty—call a plumber. It cannot be repaired.

Confirm leak location

Goal: Verify the leak is at the pressure relief valve, not elsewhere.

  • The pressure relief valve sits on the top or side of the tank or boiler with a discharge pipe running down. Check that water emerges from the valve body or the pipe.
  • If the tank or boiler itself shows wet spots, rust, or corrosion, do not proceed—call a plumber.
  • Good: Leak at valve or pipe. Proceed to Shut off power and water.
  • Bad: Tank or boiler leaking—see When to get help.

Shut off power and water

Goal: Safely isolate the system before working on the valve.

  • Turn off the circuit breaker (electric) or set the gas valve to pilot or off (gas). Shut off the cold water supply or fill valve.
  • Open a hot water faucet (water heater) or bleed valve (boiler) to relieve pressure.
  • Good: No power or gas to the unit and no water flow. Proceed to Test the valve.

Test the valve

Goal: Confirm whether the valve is faulty or weeping from high pressure.

  • Lift the lever on the pressure relief valve briefly. Water should discharge from the discharge pipe, then stop when you release.
  • Good: Drip stops after release—check discharge pipe and system pressure. Bad: Drip continues after release—valve is worn; replace it.

Replace the valve

Goal: Install a new valve that matches the pressure and temperature rating.

  • Drain a few gallons (water heater) or relieve pressure (boiler). Unscrew the old valve with a pipe wrench. Buy an exact match. Apply pipe thread sealant and install the new valve. Refill and restore power or gas.
  • Good: No drips after replacement. Bad: Still drips—check system pressure or expansion tank; call a plumber if needed.

When to get help

Call a plumber if:

  • The tank or boiler itself is leaking.
  • The valve still drips after replacement.
  • You need an expansion tank installed.
  • System pressure stays high.
  • You have a gas unit and are not comfortable.

If you smell gas, evacuate and call 911 or your gas utility from outside.

Verification

  • The leak is at the pressure relief valve or discharge pipe, not the tank or boiler.
  • The valve passes the lever test (brief discharge, then stops) or has been replaced.
  • The discharge pipe is clear and system pressure is in the safe range.
  • No drips at the valve or pipe after the fix.

Escalation ladder

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

  1. Confirm leak location Verify the leak is at the pressure relief valve or discharge pipe, not the tank or boiler.
  2. Check discharge pipe Confirm the pipe is not blocked.
  3. Test the valve Lift the lever briefly; if it drips after release, replace the valve.
  4. Replace the valve Drain, unscrew the old valve, install an exact match.
  5. Check system pressure If the valve still weeps, check pressure; expansion tank may have failed.
  6. Call a plumber Tank or boiler leaking, valve still drips, expansion tank needed, or not comfortable.

What to capture if you need help

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

  • Leak location (valve, pipe, tank, or boiler)
  • Valve test result (drips after lever release?)
  • Valve pressure and temperature rating
  • System pressure reading (if checked)
  • Steps already tried

Is the leak at the pressure relief valve or its discharge pipe?

The pressure relief valve sits on the top or side of the tank or boiler with a pipe running down. The tank, boiler, drain valve, and connections are different.

Dry the area. Check that water comes from the pressure relief valve or its discharge pipe—not from the tank surface, boiler seam, drain valve, or connections. Good: leak at valve or pipe. Bad: tank or boiler is wet or rusty—call a plumber; it cannot be repaired.

Yes No

You can change your answer later.

Does the valve stop dripping when you release the lever?

Lift the lever briefly. Water should discharge, then stop when you release. Constant drip after release means a faulty valve.

Shut off power and water first. Lift the lever on the pressure relief valve briefly. Water should discharge from the pipe, then stop when you release. Good: drip stops—valve may be weeping from high pressure; check discharge pipe and system pressure. Bad: drip continues after release—valve is faulty; replace it.

Yes (stops) No (continues)

You can change your answer later.

Is the discharge pipe blocked?

The pipe must run down to near the floor with no caps. A blocked pipe can cause pressure to force the valve to weep.

Check the discharge pipe. It must run down to within 6 inches of the floor with no caps or obstructions. Clear any debris. Good: pipe is clear—check system pressure; high pressure may need an expansion tank or PRV adjustment. Bad: pipe is blocked or inaccessible—call a plumber.

No (clear) Yes (blocked)

You can change your answer later.

Clear the pipe and retest

Clear debris from the discharge pipe. Retest the valve. If it still weeps, check system pressure or replace the valve.

Done

Is system pressure too high?

Water heaters: attach gauge to hose bib—target 50–60 psi. Boilers: check gauge—normal 12–15 psi. Over 80 psi (water heater) or over 15–20 psi (boiler) can cause weeping.

Check system pressure. Water heaters: attach a gauge to a hose bib. Boilers: check the pressure gauge. Good: pressure is in range—valve may have been temporarily weeping; monitor. Bad: pressure is high—expansion tank may have failed; call a plumber.

Yes No

You can change your answer later.

Replace the pressure relief valve

Drain or relieve pressure, unscrew the old valve, install an exact match for pressure and temperature rating.

Drain a few gallons (water heater) or relieve pressure (boiler). Unscrew the old valve with a pipe wrench. Buy an exact match (same pressure and temperature rating). Apply pipe thread sealant, screw in the new valve, snug with wrench. Refill and restore power or gas. Good: no drips after replacement. Bad: still drips—check system pressure or call a plumber.

Fixed Still drips

You can change your answer later.

Leak is resolved

The valve no longer drips. Monitor for a few days. If it weeps again, check system pressure or expansion tank—see Fix an expansion tank that is waterlogged.

Done

Call a plumber

Call a plumber if: the tank or boiler is leaking, the valve still drips after replacement, you need an expansion tank or PRV work, or you have a gas unit and are not comfortable. If you smell gas, evacuate and call 911 or your gas utility from outside.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a pressure relief valve leak?
Common causes: a worn or faulty valve seat, high system pressure (failed expansion tank or stuck fill valve), or a blocked discharge pipe. The valve releases when pressure or temperature exceeds safe limits—constant dripping means the valve or system pressure needs attention.
Can I replace a pressure relief valve myself?
Yes, if you shut off power, gas, and water first. Drain enough to relieve pressure, unscrew the old valve, and install a new one with the same pressure and temperature rating. Use pipe thread sealant. Call a plumber if you have a gas unit and are not comfortable.
When should I call a plumber for a pressure relief valve leak?
Call a plumber if: the tank or boiler itself is leaking, the valve still drips after replacement, you need an expansion tank installed, system pressure stays high, or you are not comfortable with the work. If you smell gas, evacuate and call 911 or your gas utility from outside.

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