How to Protect Plumbing in a Vacant or Vacation Home

Two homes can sit empty through the same January and reach spring in completely different shape. The difference is rarely luck. It comes down to one early choice: do you keep the heat running and watch the place, or do you shut the water off and drain it down. This guide is about making that choice well. The actual drain-down procedure is its own job, and you can see our guide on how to winterize your home’s plumbing (128) for those steps. Here the focus is the decision and the protection layers that hang off it.

The reason this matters is plain. An empty house has no one to hear a pipe let go at 3 a.m. A small leak that an occupant would catch in minutes can run for days or weeks, and a frozen line that bursts can flood every floor below it before anyone returns. Your job before you leave is to remove the conditions that let that happen.

The First Decision: Keep Heat On or Fully Shut Down

You have two legitimate paths, and almost every protection step follows from which one you pick. Path one is to keep the home heated above freezing and monitored. Path two is to shut off the water supply, drain the system, and let the house go cold. Both can be done correctly. The wrong move is the half-measure in between: heat turned off to save money, but water left in the pipes and no one checking.

This is not only a comfort question. Many homeowners policies treat it as a coverage condition. The District of Columbia’s insurance regulator states the standard plainly: maintain heat in the property, generally no lower than 55 degrees Fahrenheit, or, if the property will have no heat, shut off the water supply and drain the system and appliances of water. Carriers in cold-weather markets phrase it the same way, and a frozen-pipe claim on an unheated, undrained vacant home is exactly where coverage tends to be denied. Read your own policy before you decide, because the choice you make has to match what your insurer expects.

So the decision is not really “heat or no heat.” It is “heated and watched” versus “drained and empty.” Pick one fully and execute it.

How Long the Home Sits and How Cold It Gets Drive the Choice

Match the protection level to two variables: how long the home will be empty and how cold the climate gets. Those two facts should settle the path for you.

A home empty for a long weekend or a couple of weeks, in a region with mild winters, can usually stay heated with light monitoring. A second home that sits unoccupied for months in a hard-freeze climate, with no one able to check on it, is the textbook case for a full shutdown and drain-down. The longer the vacancy and the colder the climate, the more the math tips toward draining, because every extra week is another week for a furnace to fail or a power outage to cut the heat with no one present to notice.

The freeze threshold itself depends on the pipe, not on a single magic number. The Department of Energy notes that the temperature at which pipes freeze depends on where they run, what they are made of, and how well they are insulated, and that in southern states problems often begin around 20 degrees Fahrenheit. A line buried in an exterior wall or running through an unheated crawl space freezes long before a line in a warm interior chase. If you want the full breakdown of which pipes are most at risk, see our guide on why pipes freeze and which ones are most at risk (124).

Two more factors should weigh on the decision. Can someone reliably check the property, and is the heating system dependable? Honest answers here often flip a borderline call toward draining. A monitored home leans toward keep-heat-on. An unmonitored one in a cold climate leans toward shut-it-down.

The Keep-Heat-On Path: Minimum Thermostat, Sensors, and a Check-In Person

If you keep the heat on, the goal is simple: hold every part of the house safely above freezing, and make sure a problem reaches a human fast. Three things carry this path.

First, the thermostat setting. Set it well above freezing rather than at the bare minimum. The common insurer and utility benchmark is to hold the home no lower than about 55 degrees Fahrenheit, and many people set 55 to 60 to leave a margin. The Department of Energy’s guidance is a useful caution here: how low you can safely go depends on your pipe layout and insulation, so a house with long runs through unconditioned space needs more cushion than a tight, well-insulated one. Do not chase the lowest number that “feels” safe. The savings from a few degrees are tiny next to the cost of a burst pipe.

Second, help warm air reach the cold spots. Open the cabinet doors under kitchen and bathroom sinks, especially where supply lines run against exterior walls, so heated room air can circulate around the pipe. Interior doors left open help the warm air move through the house instead of pooling in the heated core while a far corner drops below freezing.

Third, and most important for an empty home, arrange a real check-in. A furnace can quit and a power outage can kill the heat while you are away, and a thermostat reading on a dead system tells you nothing. Ask a neighbor, friend, or property manager to walk the house on a set schedule, and make sure they know where the main water shutoff is and how to reach you. A monitored, heated home is genuinely safe. A heated home no one ever looks at is a gamble on the weakest link, usually the furnace or the grid.

Leak and Freeze Alarms and Automatic Shutoff Valves for Empty Homes

The modern layer that older advice skips is remote monitoring, and for a vacant home it does what a check-in person cannot: it watches every hour, not once a week. These devices fall into two useful groups.

Leak and temperature sensors are small, battery-powered units you place at high-risk spots: under sinks, behind the water heater, near the washing machine, in a basement or crawl space. They send an alert to your phone when they detect water or when the temperature drops toward freezing. A freeze alarm is the one that earns its keep in an empty home, because it warns you the house is getting cold before a pipe actually bursts, while you still have time to call someone to restore heat.

The stronger tool is an automatic shutoff valve installed on the main line. These monitor flow and, depending on the model, temperature, and they close the water supply on their own when they sense an abnormal continuous flow or a low-temperature condition. Many let you shut the water remotely from an app as well. For a home you cannot reach quickly, an automatic shutoff turns a catastrophic flood into a contained event, because the water stops the moment something goes wrong instead of running until your return.

One firm boundary: installing an automatic shutoff valve on the main line, or any work on the supply piping and the home’s electrical, is a licensed plumber’s job, not a DIY afternoon. Placing battery sensors yourself is fine. Cutting into the main and wiring a powered valve is not. Have a licensed plumber size and install it. Whatever devices you use, confirm they are armed, the batteries are fresh, and the alerts actually reach your phone before you walk out the door. An alarm no one receives is no alarm at all.

When to Choose Full Shutdown Instead

Choose the full shutdown when the home will sit empty for an extended stretch in a freezing climate, when no one can check on it reliably, or when you simply do not want to depend on a furnace and the power grid for weeks or months. With no water in the lines, there is nothing to freeze and nothing to leak. It is the most durable form of protection for a long, unwatched vacancy.

The shutdown path means closing the main supply, draining every line and fixture, emptying or protecting the water heater, and dealing with the traps so sewer gas does not seep back in. Those are real steps with real order, and they live in our guide on how to winterize your home’s plumbing (128). Follow that procedure rather than improvising, because a half-drained system can still hold enough water in a low spot to crack a pipe. Outdoor faucets, hose bibs, and any irrigation system need their own attention before a freeze as well, covered in our guide on how to winterize outdoor faucets and hose bibs (160) and our guide on how to winterize a sprinkler or irrigation system (163).

If your trip is short and you plan to keep the home heated and return soon, full shutdown is overkill. That lighter pre-trip routine is its own topic, and you can see our guide on how to prepare your plumbing before a vacation (182) for it. The full drain-down is for the home that goes cold and stays empty.

Restarting the System Safely When You Return

Bringing a drained or long-idle home back to life is not just “turn the water back on.” Water that has sat still in pipes for weeks or months loses its disinfectant residual and can grow bacteria, including Legionella, and a system refilled carelessly can deliver that water to your first shower. A short, deliberate restart fixes this.

Open the main supply slowly and let the system refill while you watch for leaks at fixtures, under sinks, and around the water heater, where a winter freeze-thaw can show up as a fresh drip. Then flush the lines. The CDC’s guidance for water systems that have been unused for a prolonged period is to flush both hot and cold water through every fixture until the water inside the pipes is fully replaced with fresh water, taking care to minimize splashing and spray while you do it. Run cold taps first, then the hot side.

For the water heater, refill the tank completely before you restore power or relight the burner, because energizing a dry electric element or a dry tank can damage it. The CDC advises that the water heater be set to at least 140 degrees Fahrenheit to limit bacterial growth, and that hot water at the tap should reach roughly 120 degrees or higher during the flush. Because water that hot can scald, mixing valves and careful tap use matter once the system is back; you can see our guide on how to prevent scalding from hot water at home (157) for that side of it. If you suspect a line froze and cracked while you were away, or the water heater will not refill or fire correctly, stop and call a licensed plumber rather than forcing it. The same stagnant-water concern is covered in our guide on Legionella and home plumbing (159).

Frequently Asked Questions

What temperature should I keep a vacant house in winter?
Hold it well above freezing rather than at the edge. A common insurer and utility benchmark is no lower than about 55 degrees Fahrenheit, and many people set 55 to 60 for a margin. How low you can safely go depends on how your pipes are routed and insulated, so a house with long runs through unheated space needs more cushion. Many homeowners policies require either maintained heat or a fully drained system for an unoccupied home, so check yours.

Is it cheaper to drain the plumbing or keep the heat on?
For a short, monitored absence, keeping the heat on is usually simpler and cheaper. For a long vacancy in a cold climate with no one checking, draining the system is the safer choice, because the small heating savings are dwarfed by the cost and disruption of a burst pipe in an empty house.

Do I really need a freeze alarm or automatic shutoff for a vacation home?
They are not required, but they close the gap that an empty home creates. A freeze sensor warns you the house is getting cold before a pipe bursts, and an automatic main-line shutoff can stop a leak on its own while you are away. For a home you cannot reach quickly, both turn a potential flood into a manageable alert.

Can I install an automatic water shutoff valve myself?
You can place battery-powered leak and freeze sensors yourself. Installing an automatic shutoff valve on the main supply line involves the water main and electrical wiring, which is a licensed plumber’s job. Have a professional size and install it.

What should I do first when I come back to a home that was shut down?
Open the main slowly, watch for leaks as the system refills, then flush both hot and cold lines at every fixture until fresh water replaces the water that sat in the pipes. Refill the water heater fully before restoring power or relighting it, and confirm the temperature setting before normal use.

This is general information, not professional advice. For installation, electrical, gas, or main-line work, consult a licensed plumber and follow your local code and your insurer’s requirements.

Sources

U.S. Department of Energy, Turn Down the Temperature, but Don’t Let Your Pipes Freeze!: https://www.energy.gov/energysaver/articles/turn-down-temperature-dont-let-your-pipes-freeze
Centers for Disease Control and Prevention, Reopening Buildings After Prolonged Shutdown or Reduced Operation (Control Legionella): https://www.cdc.gov/control-legionella/php/guidance/building-water-system.html
U.S. Environmental Protection Agency, Legionella in the Indoor Environment: https://www.epa.gov/indoor-air-quality-iaq/legionella-indoor-environment
District of Columbia Department of Insurance, Securities and Banking, If My Frozen Pipes Burst, Am I Covered by Insurance?: https://disb.dc.gov/page/if-my-frozen-pipes-burst-am-i-covered-insurance