plumbing troubleshooting
Repair water heater leak
Common symptoms: water around water heater; puddle under tank; drip from TPR pipe; leak from drain valve; leak at top connections; rust at base of heater
Stop and call a pro if:
- water near electrical
- TPR valve discharge (overpressure/overheat)
- tank rupture risk
- gas appliance with standing water
Step-by-step diagnostic flow
Step 1
Is water on the floor in contact with the water heater's electrical connections, an outlet, an extension cord, or the gas burner compartment of a gas heater?
Step 2
Is water currently or recently coming out of the TPR (temperature & pressure relief) discharge pipe — the pipe running down from a valve near the top of the tank?
TPR discharge means the tank hit unsafe temperature or pressure. Even if it stopped, the cause is still present.
Step 3
Dry the area, then watch for 10–20 minutes. Where exactly is the water coming from?
Look closely with a flashlight. Condensation on a cold inlet pipe in a humid space can mimic a leak — feel for drips, not just puddles. If the only wet spot is the floor pan with no traceable source, water is probably running down from above.
Possible outcomes
Kill power to the heater from the panel — then call a pro
high confidenceStanding water at electrical connections or a gas burner compartment is a shock and ignition hazard.
- Do NOT touch the heater or step into the water
- From the electrical panel, turn the water heater breaker OFF (and the main breaker if you cannot identify the right one safely)
- For gas: turn the gas shutoff valve on the gas line going into the heater to OFF (perpendicular to the pipe)
- Close the cold-water supply valve above the tank
- Call a licensed plumber (and electrician if anything is wet at the panel or an outlet)
Shut the heater down and call a plumber today
high confidenceTPR discharge means the tank exceeded safe temperature or pressure. The cause — failed thermostat, stuck gas valve, expansion-tank failure, or thermal expansion against a closed system — is still present and can rupture the tank.
- Turn gas control to OFF (or flip the heater's breaker)
- Close the cold-water shutoff valve above the tank
- Do NOT cap, plug, replace, or 'tap' the TPR valve to stop the drip — that valve is the only thing preventing rupture
- Call a licensed plumber the same day
- If you hear the tank making rumbling, popping, or hissing sounds, leave the area and call from outside
Likely a loose connection or failed flex — DIY-friendly
medium confidenceDrips at the hot or cold connection at the top of the tank usually mean a loose union, failed flex line, or a bad nipple seal — repairable without touching the tank itself.
- Close the cold-water shutoff valve above the tank
- Open a hot tap upstairs to relieve pressure
- Wipe everything dry and confirm exactly which fitting is wet
- Snug (don't crank) the union nuts on flex connectors; if a flex line is corroded or bulged, replace it
- If the leak is at a threaded nipple coming out of the tank, that's a harder job — call a plumber
- After any tightening, restore supply and watch for 30 minutes
- Photo of the connection
- Flex line brand/length if replacing
- Tank age
Drain valve leak — close, cap, or replace
medium confidenceDrain valves often weep after a flush or if debris is stuck in the seat. A brass hose cap on the outlet is a safe interim fix; a stripped or stuck-open plastic valve is a bigger job.
- Try gently closing the valve fully — sometimes it was left slightly open
- If still dripping, thread a 3/4" brass garden-hose cap with a washer onto the drain valve outlet — this stops the leak safely as a short-term fix
- Schedule a plumber to replace the valve (brass ball-valve is the durable upgrade) unless you are comfortable draining the tank and swapping the valve yourself
- Do NOT force a stuck plastic valve — it will strip and you'll have no shutoff
- Photo of valve
- Tank age
- Plastic vs brass
Tank has failed — plan for replacement, do not attempt to repair
high confidenceWater emerging from the base of the tank, or pooling in the pan with no traceable upper source, means the inner steel tank has corroded through. There is no safe DIY patch — the glass lining cannot be repaired.
- Close the cold-water supply valve above the tank
- Turn gas to OFF or flip the electric breaker
- Open a hot tap upstairs to relieve pressure
- If it's leaking faster than slowly, connect a hose to the drain valve and route to a drain to control the discharge
- Get on a plumber's calendar for replacement — see the 'Replace water heater' guide for what to know going in
- Do not be talked into 'sealing' a base leak — it will fail again, possibly catastrophically
- Data plate photo (capacity, fuel, year)
- Fuel type
- Whether expansion tank exists
- Photos of current install
Document and watch — leak source unclear
low confidenceSome leaks are intermittent (only when heating cycle pressurizes the tank). Without a known source, it's not safe to guess at a repair.
- Put dry paper towels in a ring around the base and on top of the tank
- Check every few hours and note which towel wets first
- If you see any wet patch under the tank itself, treat as tank failure (see replace-water-heater guide)
- If the leak grows, close the cold-water supply and call a plumber
- Photos of wet patches with time stamps
- Tank age
- Whether it correlates with heating cycles
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