Shut it down
- Close the cold water valve on the pipe going into the top of the tank.
- Electric: turn off the breaker. Gas: turn the gas control to Off or Pilot.
- If water is spreading, put down towels or a pan and move anything stored nearby.
Find the source
- From the bottom of the tank: usually the tank itself has rusted through. That can't be repaired, and the tank needs replacing.
- From the pressure relief valve or its pipe: the valve may be worn, or pressure or temperature is too high. This is a safety device, so have a plumber check it rather than plugging it.
- From the fittings on top: loose or corroded connections are often a straightforward repair.
- From the drain valve near the bottom: a dripping drain valve can usually be tightened or replaced.
- Puddle but no visible leak: condensation on a gas unit, or a nearby pipe, can look like a tank leak.
See typical prices in what a new water heater costs.