Before you troubleshoot

Water heater emergency safety checklist.

When the unit is leaking, smells like gas, or repeatedly trips a safety device, the first job is to make the area safe. A diagnosis can wait.

Use the matching first move

• Active flooding: close the cold-water shutoff if you can reach it without standing in water. Keep people away from the area and call a plumber. If water is near electrical equipment, leave the power off.
• Gas odor, soot, or a burner bang: leave, call the utility from outside, and do not relight or reset the appliance.
• 240-volt breaker trip: leave the breaker off. Never hold it on, replace it with a larger breaker, or open a cover without proving power is dead.
• Water near an electric heater: do not touch the appliance or panel while standing on a wet floor. Have a qualified person isolate the circuit.
• Relief valve discharge or very hot water: keep clear of the discharge. Never cap or plug a T&P valve; it protects against dangerous pressure and temperature.
• Carbon monoxide alarm: leave the building and call emergency services. A power-vent or atmospheric water heater that produces CO needs a qualified inspection.

Safe information to collect

From a safe location, photograph the rating plate, control display, status-light pattern, and the water source. Note whether the problem affects every fixture and whether it began after a storm, outage, freeze, or installation. That information helps a licensed technician arrive prepared.

When to call now

Call a licensed professional for any gas-control, combustion, pressure-vessel, 240-volt, repeated safety-trip, or leak-from-the-tank problem. If you are unsure which system you have, stop at the exterior label and get help.