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us Home & property emergencies water heater tpr valve dripping • temperature pressure relief valve leak • t&p valve releasing water • relief valve discharge pipe dripping • intermittent tpr discharge • water heater overpressure worry • water heater overheating concern • scalding risk relief valve • water heater hissing relief • expansion tank problem • thermal expansion in plumbing • high water pressure house • pressure reducing valve failing • water heater temperature too high • relief valve not seating • safety valve leaking hot water • unknown leak at water heater • water heater safety device • relief valve discharge warning

What to do if…
your water heater’s pressure relief valve is releasing water intermittently and you’re unsure why

Short answer

Treat intermittent T&P (temperature/pressure) relief valve discharge as a safety event: keep clear of the hot discharge and shut off the water heater’s energy source now. Then get a licensed plumber to check pressure/temperature control before you try to “stop the leak”.

Do not do these things

  • Do not cap, plug, clamp, or block the T&P valve outlet or discharge pipe.
  • Do not install or close any shutoff on the discharge line (and don’t “temporarily” pinch the pipe).
  • Do not test the valve lever while it’s hot or actively discharging if you’re unsure — hot water can blast out and the valve may not reseat.
  • Do not touch the discharge water/pipe with bare skin (scald risk).
  • Do not ignore it because it “only drips sometimes” — intermittent discharge can still signal unsafe pressure/temperature.

What to do now

  1. Keep people away from the discharge and prevent burns.
    Make space around the discharge pipe termination. If safe, place a bucket under the end of the pipe (never obstruct the pipe opening).

  2. Shut off the energy source to the water heater (do this first).

    • Electric: switch off the breaker labeled for the water heater.
    • Gas: turn the control to the OFF setting (or follow the heater’s shutdown instructions).
      This reduces the risk of overheating while you stabilise things.

  3. If the discharge is heavy/continuous or steaming: leave space and escalate.
    Keep clear of the heater and discharge path. Call an emergency plumber. If you believe there is immediate danger you can’t safely control, leave the area and call 911.

  4. If it’s still discharging after the heater is off, stop the water feed to reduce ongoing flow (only if you can identify it confidently).
    Turn off the cold-water shutoff valve feeding the water heater (often on the cold line above the heater). If you’re not sure which valve it is, don’t guess — get help.

  5. Once calm, reduce the chance of repeat overheating (a temporary safety step, not a fix).
    When the heater is no longer actively heating, set the thermostat to a moderate setting that’s often recommended for safety/energy (commonly around 120°F, but follow your manual and household needs). If scald risk is a concern (kids/older adults), err on the safer side and discuss mixing/tempering options with a plumber.

  6. Arrange a licensed plumber and tell them what to check.
    Ask them to evaluate:

    • House water pressure (high pressure can trigger T&P discharge).
    • Thermal expansion (especially in “closed” systems; expansion tank issues are common).
    • Thermostat/controls (overheating) and T&P valve condition (debris/corrosion/failure).
      If you’re a tenant, notify your landlord/property manager promptly and treat it as a safety repair.

  7. Capture quick evidence for the plumber (30 seconds).
    Take a photo/video of the valve area and discharge, and note: when it happens (during heating? after hot water use?), whether it stops when power/gas is off, and approximate volume (drips vs. spurts).

What can wait

  • You do not need to diagnose the exact root cause right now.
  • You do not need to drain the tank unless a professional instructs you to.
  • You do not need to replace the water heater tonight — many cases are pressure/expansion/control/valve related.
  • You do not need to “prove” the valve is bad by testing it yourself during an active event.

Important reassurance

The T&P relief valve exists to prevent dangerous overpressure/overheating. Water coming out can feel scary, but it’s the safety device doing its job. Your priority is to keep it unblocked, shut off heating, and get it assessed — without taking risky shortcuts.

Scope note

This is first-steps-only guidance to stabilise the situation and avoid irreversible mistakes. A plumber may need to measure pressure, verify expansion control, and confirm the valve and discharge setup meet code/manufacturer requirements.

Important note

This guide provides general information, not a diagnosis or a substitute for an on-site inspection. If you’re unsure which switch or valve controls the heater, stop at the safest step (keep clear, shut off energy if you can do so safely) and get professional help.

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