Troubleshooting
Why Is My Water Heater Pressure Relief Valve Leaking?
A dripping temperature-and-pressure (T&P) relief valve usually means it's doing its job: relieving excess pressure or temperature inside the tank. The most common cause in Phoenix is high incoming water pressure or thermal expansion with no working expansion tank, not a faulty valve. Don't cap or plug the discharge pipe, because that turns the tank into a safety hazard.
What to do right now
- Check that the discharge tube points down and is not capped. Never plug it.
- Have your incoming pressure tested with a gauge on a hose bib (should be 50-70 psi)
- Lower the thermostat to about 120F and watch whether the dripping stops over the next day
Likely causes
- High municipal water pressure (over 80 psi) pushing past the valve's relief threshold
- Thermal expansion with a failed or missing expansion tank, common on closed systems with a pressure-reducing valve
- Water temperature set too high, causing the valve to relieve
- A worn or mineral-fouled valve seat that no longer seals, accelerated by 16-20 grain hard water
When to call a pro
If the quick fixes do not solve it, this is usually a water heater repair & replacement job. Liberty dispatches 24/7 with upfront pricing.
Why Is My Water Heater Pressure Relief Valve Leaking?, FAQ
- Is a leaking relief valve dangerous?
- The valve itself is the safety device, so a drip is a warning, not the danger. The danger is ignoring it or blocking the discharge line, which takes away the tank's only overpressure protection.
- Will replacing just the valve fix it?
- Only if the valve seat is worn out. If the cause is high pressure or thermal expansion, a new valve will drip too, until you add an expansion tank or a pressure-reducing valve.
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