T&P Valve Leaking? Causes, Dangers, and What to Do

What the T&P Valve Does

The temperature-and-pressure relief valve is your water heater's emergency escape hatch. If temperature exceeds 210°F or pressure exceeds 150 PSI, it opens and dumps water — preventing a catastrophic tank rupture. When it drips during normal operation, it's telling you something is wrong upstream.

The Three Causes of T&P Dripping

1. Thermal expansion (most common): In closed plumbing systems, heated water has nowhere to expand, so each heating cycle spikes pressure until the valve weeps. 2. High incoming pressure: Municipal pressure above 80 PSI keeps the system near the valve's threshold constantly. 3. A worn valve: Springs weaken and seats corrode; after 5–10 years the valve may not reseat properly.

Why Winter Makes It Worse

Cold snaps are peak T&P season in Medford. Near-freezing inlet water means longer, hotter burner cycles and bigger expansion spikes — right when aging valves are least able to reseat. If your discharge pipe started dripping in January, winter is almost certainly involved.

Why You Must Never Cap It

Plugging or capping a dripping T&P valve is one of the most dangerous DIY moves in homeownership. You're removing the tank's only overpressure protection — a water heater can become a literal rocket under failure conditions. It's also a code violation everywhere. The drip is a symptom; capping it treats the symptom by creating a hazard.

The Real Fix

We test your home's water pressure, check for a failed or missing expansion tank, and replace the valve with a correctly rated unit. In most cases, adding or replacing the thermal expansion tank solves the root cause permanently — and costs far less than replacing T&P valves every winter.

Frequently Asked Questions

Related Services

• T&P Valve Replacement in Medford, MA
• Leak Detection in Medford, MA