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What does leaving on vacation without shutting off the water cost?

Updated August 2026

← What skipping home maintenance costs

Leave on vacation without closing the main and a $20 washer hose or a tired supply line can let go and flood for days, a $5,000 to $40,000+ claim that ranks among the leading causes of home water damage. Nobody is home to hear the rushing water or the ceiling coming down, so a failure a plumber would stop in minutes instead runs the entire time you are gone. Closing the main valve on the way out takes about 30 seconds and costs nothing, and it removes the pressure that drives every one of those failures. The catch is worth stating plainly: the cheapest prevention on this page is free, and the worst outcome can total a finished basement and the floors above it.

The escalation ladder

Every row below is the same leak, left a little longer. The top is a cheap warning; the bottom is a claim.

Cost of ignoring it, cheapest to worst (Updated August 2026)
What happens Typical bill How fast
You close the main before any trip past a weekend $0, 30 seconds Before you leave
Your main is seized, so you replace the valve $150–350 installed A half-day job
You add leak sensors or a smart auto-shutoff $50–500 one time One install
A supply hose fails while you are gone a weekend $1,500–5,000 in damage 2–3 days running
A line lets go early in a week-long trip $5,000–40,000+ across floors 5–7 days running

Warning signs

The risk here stays invisible until it floods, so the warning signs are about your setup, not a symptom. A main valve that is stiff, weeps, or will not close fully is the biggest red flag, since a seized shutoff is useless in an emergency; older multi-turn gate valves are notorious for this. Before any trip, eyeball the washer supply hoses for bulges, rust, or cracking, and check under the water heater and sinks for damp or corrosion. If you cannot locate a whole-house shutoff at all, treat that as the sign to have one added before you leave town again.

The prevention math

The whole prevention is a 30-second, $0 habit: close the main water valve before any trip longer than a weekend, which strands every hose, valve, and appliance connection so a failure has nothing to push. Test the valve twice a year by fully closing and reopening it so it never seizes when you need it; a plumber replaces a stuck main for $150–350, and the timing is covered in how often to test the main shutoff. For coverage while you are gone, add $50 leak sensors or a smart auto-shutoff valve. In winter, still leave the heat on so the closed system does not freeze, which is its own expensive failure.

Every line in that table starts with a skipped 10-minute task. OnOtto keeps the 10-minute version on your calendar so the $2,000 version never happens.

Get the nudge before the bill

Frequently asked questions

Where is my home's main water shutoff valve?

Follow the water line in from where it enters the house, usually on the street-facing wall of the basement, crawl space, or a utility closet, often within a few feet of the meter. In warm climates with slab foundations, it is frequently in an outdoor box near the curb or on an exterior wall by the hose bibb. It is a lever you turn a quarter-turn, or a round wheel you spin clockwise. Find it and tag it before you ever need it in a hurry.

Do I need to shut off the water for just a weekend?

For a night or two with the heat on and a sound plumbing system, most people do not bother. The habit pays off for any trip longer than a weekend, when a slow leak or a burst hose has days to run undetected. If it takes only 30 seconds to close the valve, the math favors doing it before nearly every trip. At minimum, shut it for weeklong absences, seasonal departures, and any time you already know a hose or heater is aging.

Should I turn off the water heater when I shut the main?

It is smart to. With the main closed and no water being used, a gas heater on its normal setting can keep cycling and an electric element can dry-fire if the tank ever drains, so switch a gas unit to its vacation or pilot setting and flip an electric unit off at the breaker. This also saves energy while you are gone. Turn it back to normal and let the tank confirm it is full of water before you relight or re-energize it.

What about the ice maker and irrigation if I close the main?

Closing the main stops everything downstream, which is exactly the point, but plan for a few things. Toss any ice made right before you leave, since the maker will sit dry. If your irrigation timer runs off a supply line teed in before the main, its zone valves are unaffected, but a system plumbed after the main will not run, so pause the controller. For a whole-house humidifier or a fountain, shut those off too so nothing runs a pump dry while you are away.

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