1. Make it safe
Close the cold-water inlet valve on the pipe entering the top of the heater. For an electric heater, switch off its breaker; for gas, turn the control knob to Off. Keep people away from hot water on the floor.
2. Find where the water comes from
- Top of the heater: loose inlet/outlet connections or a leaking pipe — usually repairable
- Relief valve or its discharge pipe: excess pressure or a failed valve — have pressure and the expansion tank checked
- Drain valve near the bottom: a loose or worn valve — replaceable
- Underneath, from the tank itself: the inner tank has corroded through — replacement
3. Protect the room
Attic and upper-floor heaters should sit in a drain pan piped to a safe location. If yours doesn't have one, water will reach the ceiling below quickly — put towels and a bucket down and call.
When to call about a leaking water heater
Call a plumber for any tank leak, any relief-valve discharge, a gas smell, or water near electrical components. If the tank itself is leaking, it cannot be patched — see when to replace a water heater.
Where the leak is coming from matters
Water from the relief valve discharge pipe usually means too much pressure or temperature, often a failing relief valve or a missing expansion tank. Leaks at the pipe connections on top are usually fixable. Water coming from under the tank or the tank shell means the tank itself has failed and the heater needs replacing.
Water Heater Leaking? What to Do Now: when to call a pro
- You smell gas
- The relief valve is discharging
- Water is leaking from the tank body
Water Heater Leaking? What to Do Now: common questions
Can I still use hot water if my water heater is leaking?
If the leak is from the tank, shut off the cold water supply to the heater and turn off the gas or power until it is replaced.
Do I need an expansion tank?
Homes with a pressure-reducing valve or backflow preventer usually need a thermal expansion tank; many codes require one when a water heater is replaced.
Can a leaking water heater be fixed?
Leaks from fittings, the drain valve or the relief valve often can. A leak from the tank body can't be repaired.
Is a leaking water heater an emergency?
Shut off the cold-water supply and the power or gas right away. A small leak can wait for a scheduled visit; a large one needs prompt help.
Every home differs; editorial standards.