How to Fix a Leaking Water Heater Temperature & Pressure (T&P) Valve
Time required: 30-45 mins · Difficulty 2/5
Warning: Always shut off the gas/power supply and cold water shutoff before replacing a T&P valve. High pressure water can cause severe scalding.
Est. DIY Parts: $15 - $30 · Pro Service: $180 - $300 · Est. Savings: $150 - $270
* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.
Parts & Tools You'll Need
- Cash Acme 3/4 in. NCLX-5 Temperature & Pressure Relief Valve
- PTFE Heavy-Duty Thread Seal Tape
- 10-inch Pipe Wrench
- 5-Gallon Bucket
- Garden Hose (for draining tank)
Step-by-Step Manual
- Turn off power/gas and water supply Switch off the circuit breaker for electric heaters, or turn the gas control valve to PILOT. Close the cold water inlet valve on top of the tank.
- Drain 2-3 gallons below the valve level Connect a garden hose to the bottom drain valve and empty 2 to 3 gallons into a bucket or floor drain to bring the water level below the T&P port.
- Disconnect the discharge pipe Use a pipe wrench to unscrew the vertical copper or PVC discharge pipe running down the side of the tank.
- Unscrew the old T&P valve Firmly turn the old valve counterclockwise using your pipe wrench until it releases from the tank wall.
- Wrap Teflon tape and install new valve Wrap 5-6 layers of PTFE tape clockwise around the male threads of the new valve, then screw it in and tighten firmly until the discharge port faces down.
- Reattach discharge pipe, refill, and test Reinstall the discharge pipe, turn cold water back on to pressurize the tank, bleed air through a hot faucet, and verify zero leaks.
Frequently Asked Questions
Why is water leaking or dripping from my water heater pressure relief valve?
A leaking Temperature and Pressure (T&P) relief valve typically indicates one of three issues: excessive water temperature, dangerously high municipal water pressure (above 80 PSI), or mineral sediment buildup preventing the valve spring from sealing tightly.
Can I just cap or plug a leaking water heater relief valve?
NEVER cap or plug a leaking T&P valve. It is the most critical safety device on your water heater designed to prevent catastrophic tank explosions. If it is leaking, it must be flushed to clear sediment or replaced immediately—never capped.
How much does it cost to replace a water heater T&P valve?
Replacing the valve yourself costs only $15 to $30 for a standard 3/4-inch replacement valve and Teflon tape. Hiring a licensed plumber typically costs between $180 and $300, which includes labor and water pressure testing.