How to turn off a water heater (and when you should)

If it's leaking right now

1. Turn off the energy: gas knob to off, or the electric breaker off.
2. Close the cold water shutoff valve on the inlet pipe at the top of the heater. That stops more water entering the tank.
3. If water is still coming from the cold line or the valve won't close, shut off the main water valve to the house.
4. Move what you can away from the water and call a plumber.

If you smell gas, skip all of this. Leave the house and call 911 and your gas company from outside. For a break in the street or a water emergency at night, call your water utility. In Weymouth, Massachusetts, for example, the town routes after-hours water emergencies through the police dispatcher (see our Weymouth page).

Turning off a gas water heater

A. O. Smith's steps for a standard gas tank: turn the control knob near the bottom of the heater to off. If you need the gas fully off, find the gas shutoff valve, usually within a few feet of the heater, and turn the handle so it's at a right angle to the gas line. Some newer gas heaters also have an electrical connection for an electronic control or power vent, and A. O. Smith says to turn that off too.

Turning the knob to pilot instead keeps the pilot flame lit but stops the main burner. That's handy for short jobs because you won't have to relight it.

Turning off an electric water heater

Switch off the heater's breaker in the electrical panel. A. O. Smith notes that many water heaters have two circuit breakers on a 240 volt supply, and both must be off. Some heat pump models run on 120 volts and plug into an outlet, so you unplug them.

Never turn an electric heater back on until the tank is full. Open a hot tap and wait for a steady stream first. An element that heats in air can burn out in seconds. See water heater keeps tripping the breaker.

Going away: vacation, pilot or off?

Rheem's advice depends on how long you'll be gone:

• A few days: turn it down or use the vacation setting.
• A week or more: vacation or pilot.
• Two weeks or longer: consider turning it off completely, and expect to relight the pilot when you get back.

A. O. Smith lists its gas control's vacation or low setting at about 55°F. Rheem adds that sediment can settle during a long shutdown, so a flush may make sense when you return. In winter, keep the house heated even if the water heater is off, because a tank and pipes full of water can freeze.

Turning it back on

A. O. Smith's restart steps start with filling the tank: open the cold supply, open a hot faucet, and let water run for at least 3 minutes so there's no trapped air. Then restore gas or power and follow the lighting instructions on the heater's label. If the pilot won't stay lit afterward, see pilot light keeps going out, or how to reset a water heater for electric models.

A planned power cut affects water heaters too. Timnath, Colorado has had safety power shutoffs, and many modern gas heaters won't fire without power (see our Timnath page).

Local pages mentioned

• Timnath, CO
• Weymouth, MA