Yes. For any trip longer than a weekend, I close the main water valve before I leave.

The reason is simple. A pipe or a hose can give out at any time. When you are home, you hear it and you shut it off. When you are gone, it keeps running for days. The Insurance Information Institute puts the average water damage and freezing claim at $13,954 for 2018 through 2022, and says about one insured home in 60 files one of those claims every year. Closing a valve costs nothing.

Travelers says to consider shutting off the main water valve if you will be away for a long span of time, and to close the valves to individual appliances if you cannot shut off the main. Travelers also says to talk to a professional about shutting off your main valve first. That is fair advice, because the valve itself is sometimes the weak part. More on testing it below.

When shutting the water off matters most

Three things raise the stakes.

Freezing weather. IBHS says that if you will be away longer than a week and subfreezing temperatures are ongoing or in the forecast, consider shutting off the water by closing the main valve slowly and letting a couple of faucets drain slowly on the lowest floor of the home. Water expands as it freezes, so a frozen pipe can split, then flood the house when it thaws.

Shutting the water off is not a reason to shut the heat off. The Red Cross says that if you are going away during cold weather, leave the heat on, set no lower than 55 degrees. IBHS says at least 55 degrees too, even when nobody is home. Travelers says the same number. Leave the heat on.

How long you will be gone. A weekend is a small window. Two weeks is not.

Old supply lines. The flexible hoses behind the washer and under the sinks are what usually fail. A Connecticut Insurance Department pamphlet built on an IBHS study says a burst water supply line caused half of all water damage incidents involving washing machines, at more than $6,000 in damage per incident. The same pamphlet says washing machine makers recommend replacing those hoses every five years, and that 73 percent of losses involving an ice maker came from the supply line hose failing. IBHS says to change washer and dishwasher hoses that are more than 10 years old.

If you do not know how old your hoses are, you have your answer. Shut it off.

What to check before you close the valve

Closing the main has side effects. Five things in the house care about it.

Your water heater

A tank water heater stays full when the main is closed. The water in it does not drain out, so an electric element stays covered and a gas burner still has water to heat. On a short trip you can leave the heater alone.

On a longer trip, turn it down. Rheem says to use the vacation setting or the lowest setting for trips of 3 to 10 days, pilot mode for one to two weeks, and to shut the unit off for trips of two weeks or more. If you do shut it down, Rheem says to turn off the cold water supply as well, and that you will need to relight the pilot when you get back.

A Rheem use and care manual says that if the heater will sit idle for an extended period, the power and the water to it should be turned off, to save energy and to prevent a build-up of dangerous hydrogen gas. It says to drain the heater and its piping if they could be exposed to freezing temperatures. It also says a qualified service person should check the controls after a long shutdown, and that the tank must be completely full again before it runs.

Two safety notes from that same manual. Hydrogen gas can build up in a hot water system that has not been used for about two weeks or more, and it is extremely flammable. So when you get home, open the hot water faucet at the kitchen sink for several minutes before you run any electrical appliance on the hot water line, and keep flames away from the faucet while it is open.

The second note is about gas. If gas gets shut off at the meter, have the utility or a qualified professional restore service and relight the appliances. Do not relight them yourself. Rheem says to consult a licensed professional if you are unsure.

Rheem also mentions that sediment can collect while a tank sits unused. How often to flush your water heater is the schedule for that part.

A home fire sprinkler system

This one can turn a good habit into a real risk. The Home Fire Sprinkler Coalition warns that turning off the water to your home will also turn off the water to your fire sprinkler system, and says to contact your fire sprinkler contractor if you have questions.

Some homes have a separate valve for the house plumbing and another for the sprinklers. Some do not. Do not guess which one you are closing. Ask your sprinkler contractor which valve you can use, and write the answer down.

The ice maker

GE Appliances says to turn the ice maker off and turn off the water supply to the refrigerator when you will be away, and that any time you turn off the water to the refrigerator you must turn off the ice maker too. An ice maker that keeps trying to fill with no water can be damaged.

GE also says to leave the refrigerator running at its normal settings for a trip of a month or less, and to run a few glasses through the water dispenser when you get back to clear out the stale water.

The washer and the dishwasher

The Connecticut pamphlet says to turn supply valves off when they are not in use, and not to run the washing machine while the house is empty. Travelers says the same thing about starting any appliance on your way out the door. If you are not closing the main, close these two valves at least.

Irrigation, and whoever is checking the house

Lawn irrigation often runs off a line that splits from the supply before the valve inside your house. If yours is set up that way, closing that valve will not stop it. The sprinklers keep running, and you have no way to shut them off from inside. Find out which way yours is plumbed before the trip. Ahead of cold weather, the Red Cross says to drain water sprinkler supply lines following the manufacturer’s or installer’s directions, and not to put antifreeze in them.

Then there is the person watering your plants or feeding your cat. With the main closed, they have no tap and no working toilet. Tell them before they show up. Travelers suggests having a neighbor or friend on call anyway, in case something goes wrong while you are out.

How to find your main shutoff and test it

The valve is usually where the water line comes into the house. Look on the wall that faces the street, in a basement, crawl space, garage, or utility room, and look near the water heater. In warm climates it is more often outside.

San Francisco’s water utility describes the two kinds you will see. An older gate valve has a round wheel. You turn it clockwise until it stops. A ball valve has a lever that shuts off at a quarter turn, square to the pipe. That same utility says only its own field staff should open the water meter. So the valve you want is the one on your side of the meter, not the meter itself.

Then test it. IBHS says to know where your home’s water shut-off valve is and how to operate it. The Connecticut pamphlet goes further and says to operate your shutoff valves every six months to make sure the water really does shut off, and to replace a valve that fails.

Do that test on an ordinary afternoon, not an hour before your flight. Close the valve slowly, open a faucet, and see if the water stops. A valve that has not moved in fifteen years sometimes will not turn, or will not seal. You want to find that out while a plumber can still come out. The new homeowner checklist covers the other shutoffs worth finding in a house you just bought.

What to write down before you leave

Everything above is only useful if the right person can find it. So write down four things:

Where the main valve is, in plain words. “Basement, north wall, behind the shelving unit, left of the water heater.”
Which way it turns, and how far. A lever is a quarter turn. A wheel is clockwise until it stops.
Whether the house has fire sprinklers, and which valve your contractor said to use.
The small list for the trip: ice maker off, washer valves off, water heater setting, heat at 55 or above.

Tobi’s maintenance log is where I keep mine. The main shutoff goes in as its own record in the home, with the location and the turn direction in its notes. Then I put a recurring task on it to exercise the valve, so it comes up twice a year instead of waiting on my memory. Marking it done leaves a line in the history with the date and who did it, so a valve that nobody has touched in three years is obvious.

Everyone in the household sees the same record in real time, on their own iPhone or iPad, or on an Apple Silicon Mac. That matters here more than anywhere. The person standing in the basement with water coming down is not always the person who found the valve. The app also works without a signal, which is what a basement usually has.

What I do before a trip

A weekend away, I turn the washer valves off and leave it there.

A week or more, I close the main slowly, open a faucet on the lowest floor to drain the line, turn the ice maker off, and set the water heater to its vacation setting.

In winter, the heat stays on at 55 or higher no matter how long I am gone.

And I tell the person checking on the house that the water is off, so they are not standing in my kitchen wondering why the sink is dry.

Should you turn off the water when you go on vacation?