How To Turn Off Gas Water Heater When It's Leaking. Turning off your hot water heater will actually cost you more than if you’d just left it. After the power is taken care of, you should also turn the water off.
When the water heater leaks. Switch it to off or pilot to shut off the gas and make the heater safe to work on. If you have an electric water heater, you should shut off the power by turning off the breaker for your tank.
This is the very first thing you should do when you find a hot water leak.
Then you also see a pipe leading to a burner. If this happens to be the scenario for you, it is advised that you turn off the water through the valve on the heater to minimize leakage. Turn off a gas water heater by closing the valve on its gas line or turning the thermostat to the “off” position. Failing to do so could lead to further damage to your water heater, or moisture damage in the basement or area where your water heater is located.