PanicStation.org
UK USA
us Home & property emergencies overflow pipe running • outside discharge pipe leaking • discharge pipe won’t stop • water running nonstop outside • water heater tpr valve leaking • t&p valve discharge tube • pressure relief valve leaking • relief valve discharge outside • hot water heater overflow pipe • pipe dripping nonstop outside • water won’t stop flowing outside • toilet keeps running • toilet keeps filling • toilet shutoff valve • main water shutoff emergency • shut off water heater • prevent water damage now

What to do if…
water is running from an outside overflow or discharge pipe and won’t stop

Short answer

Don’t block the pipe. If you can do so safely, shut off the water (and shut down the water heater if the discharge seems hot), then call a licensed plumber/qualified tech urgently.

Do not do these things

  • Do not cap, plug, clamp, or tape the pipe shut — it may be a safety discharge (especially from a water heater).
  • Do not put your hand into the stream (it can be hot enough to scald).
  • Do not keep turning the water heater back on “to see if it stops.”
  • Do not repeatedly lift or “test” a relief valve handle to try to fix the leak.
  • Do not ignore steady flow; it can quickly become major water damage.

What to do now

  1. Keep everyone away and do a quick, safer check: is it likely hot or cold?
    • If you see steam, the pipe is too hot to approach, or it clearly runs from the water heater area, assume hot and go to Step 2.
    • Otherwise, briefly catch a little in a bucket and feel the outside of the bucket (not the stream). If it feels warm/hot, treat as hot.
  2. If it seems connected to the water heater (hot/warm, or the line comes from the heater): shut the heater down.
    • Turn off power: switch the breaker OFF for an electric water heater.
    • For gas water heaters: turn the gas control to OFF (follow the label/instructions on your unit).
    • Shut off the cold water supply to the water heater (the valve on the cold inlet line above the tank), if you can do so easily and safely.
  3. Shut off the home’s main water to stop the flow.
    • Close the main shutoff valve where the service line enters the home (often basement, garage, utility room, or an exterior wall).
    • If you can’t find it or it won’t turn, and water is continuing, call your local water utility’s emergency line for guidance/assistance.
  4. Quick inside check (no dismantling) for the simplest source.
    • Check toilets: if one is continuously running/refilling, close the toilet stop valve (small valve behind/under the toilet) to isolate that fixture.
    • Look around the water heater for obvious leaking at the relief-valve discharge area or pooling near the tank.
  5. Call the right help based on your situation.
    • If you rent: contact your landlord/property manager’s emergency maintenance and report “continuous discharge/overflow from exterior pipe; water shut off.”
    • If you own: call a licensed plumber. If it appears to be a water heater relief discharge, say “possible T&P relief valve discharge.”
    • Condo/apartment building: notify building management immediately (shared shutoffs/mechanical rooms may be involved).
  6. Reduce damage while waiting.
    • Put a bucket outside if it won’t overflow back toward the foundation.
    • Move items away from wet areas; use towels to contain indoor drips.
    • Take a short video/photo showing the pipe and the flow rate (helps diagnosis).

What can wait

  • You do not need to diagnose the exact failed part right now.
  • You do not need to replace a relief valve or open the water heater in the moment.
  • You do not need to decide on replacement vs repair today — stabilizing and getting qualified help is enough.

Important reassurance

A continuous exterior discharge usually means something isn’t shutting off correctly or a safety device is relieving pressure. The safest immediate moves are to avoid blocking the outlet, shut off water (and heater power if it’s hot), and bring in qualified help.

Scope note

First steps only. Repairs may involve safety devices (like a water heater T&P valve) and should be handled by a qualified professional.

Important note

This is general information, not professional or code advice. A continuously discharging water heater safety valve can indicate unsafe temperature/pressure conditions — treat it as urgent and do not obstruct the discharge pipe.

Additional Resources
Support us