Snowbird plumbing checklist: leaving an Arizona home for summer?

Shut off the main water valve. With the water off at the source, a failed supply line, a burst washing-machine hose, or a stuck toilet fill valve cannot flood an empty house. This one move is the strongest protection you have against returning to water damage.

Find the main shutoff before the day you leave. In most Phoenix slab homes it sits where the water line enters the house, often in a front exterior wall, a garage wall, or a box near the street. Turn the valve fully clockwise (a lever-style valve turns a quarter turn until it is crosswise to the pipe). After it is closed, open a faucet on the lowest level and a faucet upstairs to drain the pressure out of the lines, then close them again. If you have never located or tested this valve, see our guide on the main water shutoff.

The EPA notes that the average household's leaks add up to nearly 9,300 gallons of water wasted every year, and that about 10 percent of homes have leaks that waste 90 gallons or more a day. Those numbers describe occupied homes where someone notices and reacts. In a sealed-up house, a leak runs unchecked until the water bill or a neighbor flags it, and by then it may have soaked drywall, flooring, and cabinets. Closing the main valve removes that risk for the whole summer.

If you must leave water on, for yard irrigation or a smart watering system, isolate as much of the indoor plumbing as you can instead. Many homes have a second valve that feeds only the house while the irrigation line branches off ahead of it. Shutting the house side while leaving irrigation live gives you most of the protection without killing the watering schedule that keeps a Phoenix yard alive through July.

Pour about a quart of water into every floor drain, unused tub, shower, and seldom-flushed toilet, and add a tablespoon of mineral oil on top. The oil floats and slows evaporation so the water seal lasts the season. Flush each unused toilet so the bowl and tank hold fresh water.

Every drain has a P-trap, the U-shaped bend that holds a plug of water. That water blocks sewer gas from rising into the room. The International Plumbing Code (Chapter 10) describes the trap seal as "an essential feature... to prevent odors from the drainage piping from entering the building," and it requires that traps prone to drying be protected by a trap seal primer or a barrier device. When a fixture goes unused, the seal evaporates, and Phoenix's summer heat empties a trap far faster than a mild climate would.

A dried trap is the most common reason an empty house smells like sewage or rotten eggs when you walk back in. The fix is to keep the seals topped off before you go. If you do return to a sewer odor, our page on why a house smells like sewer or rotten eggs walks through dry traps and the other causes. Pay attention to rarely used fixtures: a guest bathroom, a laundry sink, a garage or utility-room floor drain, and the bowl of a powder-room toilet.

Mineral oil is the part snowbirds skip most often, and it is what makes this step last all summer. Plain water in a trap will evaporate over the months you are gone, especially in dry desert air. A thin film of oil on the surface slows that loss so the seal holds. Cooking oil works in a pinch, but mineral oil resists going rancid, so it will not add its own smell. A capful per drain is enough; you are sealing the surface, not filling the trap.

Set the water heater to vacation or pilot mode, or drain it if you will be gone for months. Leaving a tank heating water all summer for a house no one is in wastes energy and keeps the tank under stress. Most gas units have a thermostat dial with a "Vacation" or "Pilot" setting; electric units can be switched off at the breaker.

The Department of Energy recommends a normal setpoint of 120 degrees Fahrenheit, which slows mineral buildup and corrosion inside the tank and pipes. Phoenix's hard water already drives sediment, so a lower setting protects the heater's life. If you choose to drain the tank, shut off the gas or power first, close the cold-water inlet, connect a hose to the drain valve, and run it to a safe spot outside. Note that an empty gas or electric tank must never be fired back up until it is refilled, or the unit can be ruined.

Turn off the washing-machine supply valves, the hot and cold knobs behind the machine. Rubber washing-machine hoses are a leading cause of household floods because they sit under constant pressure. Closing those valves takes the hoses off pressure for the summer, which matters most in a house where the main valve is the only other line of defense. While you are back there, glance at the hoses for bulges or rust at the fittings.

Check the water softener if you have one. With the main water off, the softener does not need to run, so set it to a vacation or hold mode per the manual so it does not regenerate and waste salt and water on a schedule for an empty house. A unit left in normal mode can cycle brine into a closed system all summer for no reason.

Yes, a smart leak sensor or an automatic shut-off valve is worth it for a home that sits empty for months, and the EPA endorses leak-detection and shut-off devices as part of routine home maintenance. These tools catch the leak you are not there to see.

A leak sensor sits on the floor near a likely trouble spot, the water heater, under a sink, behind the washer, and sends an alert to your phone when it detects moisture. An automatic shut-off valve goes one step further: it mounts on the main line, watches for abnormal flow, and closes the water on its own when it senses a leak. For a snowbird who has already shut the main valve, a sensor is a useful backstop on any line that stays pressurized, while a whole-house auto-shutoff is the stronger choice if you prefer to leave water on for irrigation, a smart watering system, or a caretaker's visits.

Either device pairs well with the rest of this list rather than replacing it. The main shutoff is still your best defense; the sensor or valve tells you the moment something goes wrong so a neighbor or plumber can step in before damage spreads. If you keep a hot-water recirculation pump on a timer or smart control, review whether it should run at all in an empty house; our page on whether a recirculation pump is worth it covers when to leave it on.

Work top to bottom so each step sets up the next. A short routine on the way out the door is what keeps the house dry and odor-free until you return.

1. 1Locate and close the main water valve. Turn it fully off at the point where the line enters the home.
2. 2Set the water heater to vacation or pilot mode, or drain it for a long absence. Shut the power or gas first if you drain it.
3. 3Turn off the washing-machine supply valves. Close both the hot and cold knobs behind the machine.
4. 4Set the water softener to vacation or hold mode so it does not regenerate while you are gone.
5. 5Open faucets briefly to drain pressure from the lines after the main valve is closed, then shut them.
6. 6Top off every drain trap. Pour water into floor drains, unused tubs and showers, and toilet bowls, then add a little mineral oil to slow evaporation. Flush rarely used toilets.
7. 7Place leak sensors near the water heater, sinks, and the washer, or arm your automatic shut-off valve.
8. 8Tell a trusted neighbor or caretaker where the main shutoff is and how to reach you.

Running these steps takes under an hour, far less than the cost and disruption of repairing water damage or clearing a sewer smell from a closed-up house. If you would rather have a professional handle the departure walkthrough or install a leak sensor or shut-off valve, HQ Plumbing & Air serves the Phoenix metro and can set the home up before you go.