How Do I Shut Off My Water Heater?
To shut off a water heater, first turn off the cold-water valve on the pipe above the tank. Then cut the heat: switch off the heater's breaker if it's electric, or turn the gas control knob to "Off" or "Pilot" if it's gas. Open a hot faucet briefly to relieve pressure, then close it again so the leak can't get worse.
You don't need tools for any of this, and you don't need to drain the tank. Below are the details for each type of heater, plus what to do if you can't find a valve or it won't turn.
Step 1: Turn Off the Cold Water
Look at the two pipes on top of the tank. Most tanks have the word "cold" or a blue mark stamped next to the cold inlet. If you can't find a label, touch the pipes carefully after the heater has been running: the cold one is cool. Follow that pipe up to the shutoff valve.
- Lever handle (ball valve): turn it a quarter turn so the handle sits crossways to the pipe.
- Round handle (gate valve): turn it clockwise until it stops. Don't force it.
What if there's no valve, or it won't turn?
Some older setups have no shutoff on the cold line at all. Older gate valves also often seize or don't close fully (we replace stuck shut-off valves). Don't crank on them with a wrench, because they can break. Instead, shut off your home's main water. In most Apache Junction homes it's in the box near the street, or where the main line enters the house or garage. In mobile homes it's often under the home near where the supply line comes up, or at a valve on the pipe from the ground.
Step 2 (Electric): Switch Off the Breaker
An electric water heater uses a double breaker, usually 30 amps, in your main panel. It may be labeled "water heater" or "WH." Switch it fully to off.
Why turn off the power if the heater is leaking?
If water drains out of the tank while the elements are still powered, they can burn out in minutes. And water around electrical parts is never safe. If you can't find the breaker, turn off the main breaker until help arrives.
Safety: If water is near the breaker panel or an outlet, don't touch the panel while standing in water. Get to dry ground first, or call for help.
Step 2 (Gas): Turn the Gas Control to Off
On a gas water heater, the gas control valve is the box on the front near the bottom with a knob marked "On," "Pilot," "Off" and often a temperature dial.
- For a short repair, set the knob to "Pilot." This keeps the pilot lit but stops the burner. ("Vacation" only holds the water at a low temperature, so the burner can still fire.)
- For a leak or replacement, turn it to "Off."
- For a full shutoff, also close the gas valve on the supply pipe: turn the handle so it's crossways to the pipe.
- On propane, you can also close the valve at the tank.
Smell gas? Skip the shutoff steps. Don't turn the gas knob, flip the breaker or touch any switch. Leave the house first, then call 911 and your gas company (Southwest Gas, or your propane supplier) from outside.
Step 3: Relieve the Pressure
Open a hot water faucet in a nearby sink or tub for a few seconds. With the cold water off, this takes the pressure off the tank, which slows a leak at the top fittings to a drip. Then close the faucet again. Left open, it lets air into the tank, and a leak at the drain valve, bottom seam or tank body will keep emptying the tank onto your floor.
Tip: Don't open the relief valve lever to drain water. The water is scalding, and the valve may not seal again afterward.
How to Shut Off a Tankless Water Heater
Tankless units usually have isolation valves under the unit: a cold valve (often blue handle), a hot valve (often red) and small service ports between them.
- Turn off power. Press the power button on the controller, then switch off the breaker or unplug the unit if it has a cord.
- Close the gas valve on the gas line to the unit (handle crossways to the pipe).
- Close the cold and hot isolation valves under the unit.
Tankless heaters in hard water need yearly descaling through those service ports, part of our tankless water heater service. If yours is leaking at the bottom or showing an error code, call us and have the model number ready.
Mobile Homes and Outside Water Heater Closets
Nearly half the homes in Apache Junction are mobile or manufactured homes, and many have the water heater in a closet you open from outside.
- The cold-water valve is usually right above the heater inside that closet.
- The breaker is in the home's main panel inside. Some homes also have a disconnect switch on the wall near the heater; switch it off too. Gas units have a control knob on the front and a gas valve on the supply pipe.
- If the closet floor or the floor near it feels soft, keep weight off it. Particleboard floors weaken fast when wet.
More on these setups is on our mobile home water heater repair page.
Leaving for the Summer? How to Shut Down Safely
Apache Junction's population roughly doubles in winter, to about 80,000, and many of those homes sit empty all summer. A leak in an empty home can run for weeks. For a long absence, close the cold-water valve to the heater (or the main), switch off the breaker or set the gas to "Vacation" or "Off," and ask a neighbor to look in the closet or garage now and then. Our full snowbird checklist covers the rest, or we can handle it with our snowbird close-up and start-up service.
After It's Shut Off: Find the Leak
With everything off, you can safely look for the source. Our guide to every place a water heater leaks shows each spot to check. Water at the base? See water heater leaking from bottom. Dripping pipe on the side? See relief valve leaking. Wet lines above the tank? See our page on a leaking pipe above the heater. Drips at the fittings on the lid? See water on top of the tank. Water only at the burner of a gas unit may be condensation rather than a leak. For other questions, browse our water heater FAQ.
Or skip the guesswork. Apache Junction Water Heater Pros is open 24/7. Call +1 480-863-0807, or read about our emergency water heater repair and our water heater leak repair in Apache Junction.
Shutting Off a Water Heater: FAQs
Should I turn off the water or the gas first?
Turn off the cold water first to stop more water from entering the tank, then turn off the gas or power right after. If you smell gas, skip both and leave the house immediately. Call 911 and your gas company from outside.
Is it safe to leave a water heater turned off?
Yes. A water heater can stay off for days or months with no harm, as long as it's shut down properly. You'll just have no hot water. When you turn it back on, make sure the tank is full first so electric elements don't burn out.
Where is the breaker for my water heater?
It's usually a double-pole breaker, often 30 amps, in your main electrical panel, sometimes labeled "water heater" or "WH." In mobile homes, the panel is usually inside the home even when the heater closet opens from outside. If nothing is labeled, switch off the main breaker until help arrives.
Do I need to drain the tank after shutting it off?
No. Shutting off the water and heat and briefly opening a hot faucet is enough to slow a leak. The water can be scalding, so most draining is best left to whoever does the repair. One exception: if the tank itself is leaking and help is hours away, draining it outside with a garden hose once the water has cooled stops the leak, as our leaking tank guide explains.
What does the "Vacation" setting on a gas water heater do?
It keeps the pilot lit but holds the water at a very low temperature, so the burner rarely fires. It's handy for short trips. For long absences or a leak, turning the gas fully off is safer. Leaving for the summer? Our snowbird checklist covers the full shutdown.
How do I turn my water heater back on?
Open the cold-water valve first. Then open a hot faucet and leave it running until water flows steadily with no sputtering, which means the tank is full and the air is out, and close it. Only then switch the breaker on, or relight the pilot and turn the gas knob to "On" following the label. Watch the fittings for drips for the first hour.