The home water-protection checklist, by season

Scoop the gutters, then run a hose into each one and watch two things: that water moves toward the downspout instead of pooling, and where the downspout dumps it. Water should land on an extension or a splash block and travel away from the foundation, not soak the soil against the wall. A downspout that discharges at the base of the house is the most common cause of a damp basement corner we see, and it is a ten-dollar fix.

Lift the lid and pour water into the pit until the float rises. The pump should start, pump the pit down, and stop without hammering or restarting. If the pit refills right after the pump stops, water is draining back through the discharge line, which means the check valve is failing; our check valve guide covers the swap. If the pump hums without moving water, or will not start at all, it is time for a new one before the rain, not after; the sump pump buying guide and the sizing calculator are the next two stops. A pump that runs all the time is its own story: what a constantly running sump pump is telling you.

A hose left attached holds water in the hose bib and in the pipe behind it. Frost-free bibs are designed to drain when the hose is off; with the hose on, they split like any other pipe, and the break is inside the wall where it runs unnoticed. Hoses off, bibs open to drain, and if the house has interior shutoffs for the bibs, close them now and leave the outside valve open.

Drain a few gallons from the valve at the bottom of the tank into a bucket to flush sediment, and look at three places: the fittings on top, the relief valve and its discharge pipe, and the pan underneath. Rust streaks or a damp pan mean a leak has already started. Note the manufacture date on the label; tanks past a decade deserve a plan. Where water heaters leak, and the first 30 minutes when one does.

Water heater pan, behind the washing machine, in the sump pit above the high-water line, under the kitchen sink. Those four catch most of the floods that ran for days before anyone noticed. Fresh batteries in the sensors you already have, and a test of each one with a wet fingertip. The full placement map and the sensors we recommend.

A burst supply line runs at full pressure until someone closes the main, so the freeze list starts with the valve. Find it (street side of the basement or crawl space, the garage or utility closet on a slab, the meter box at the curb in warm climates), close it once, open a faucet to prove the water stops, then reopen it. Tag it, photograph it, and show everyone who lives in the house. If the handle will not move or the water does not stop, that is a plumber call before the freeze, not during it. Every valve type, and what to do when one is stuck.

If the hoses are still on from fall, this is the last call. Hoses off, bibs drained, the interior stop closed where one exists, insulated covers on. Covers are cheap insurance for the bibs on the north and west walls.

Slide insulation sleeves over exposed runs in the crawl space, the garage and any unheated space. Open the cabinet doors under sinks that sit on outside walls so room air reaches the pipes. On the coldest nights, let the faucet farthest from the main trickle; moving water is much harder to freeze, and a trickle costs less than a split pipe. If a pipe does freeze, open the faucet it feeds and warm the pipe gently with a hair dryer from the faucet back; never a torch.

Never set the heat below 55°F, including when the house is empty for the holidays. A smart thermostat that alerts when the indoor temperature falls catches a dead furnace hours before the pipes do. If the house will be empty for more than a few days in freezing weather, close the main and open a faucet to drain the pressure; a house with the water off cannot flood from a supply line.

Most leak sensors also report temperature; put one near the most exposed run and set the low-temperature alert. A smart shutoff valve on the main goes further: it closes the water on abnormal flow while you are away, which turns a week-long leak into a few gallons on the floor. Moen Flo and Phyn Plus compared, and the shutoff valves we recommend.

The soil should slope away from the house on every side. Fill the low spots that held snowmelt against the wall, put the downspout extensions back where the plow or the kids moved them, and reset the splash blocks. Look for new cracks in the foundation wall and for efflorescence, the white mineral bloom that means water has been moving through the concrete.

Thaw plus spring rain is the busiest stretch of the year for the pump. Bucket-test the primary again, listen for the check valve closing cleanly, and test the backup: a battery that sat all winter may hold almost nothing. Run the backup with the primary unplugged and time how long it keeps up. Battery backups have a service life; replace the battery on the maker's schedule, not when it fails. Installing a battery backup, the battery backups we recommend, and water-powered backups for houses on municipal water.

Clear leaves, ice and debris from each well, then pour a bucket of water in and watch the drain at the bottom take it. A well whose drain is clogged becomes a bathtub against a basement window in the first big rain. Covers keep the debris out and stop the problem from coming back.

Clean the filter and the coil, confirm the drain line runs downhill to a drain or that the condensate pump works, set the unit to hold 50 percent relative humidity or below, and start it before the humid weeks rather than after the smell arrives. The EPA's guidance is to keep indoor humidity below 60 percent and ideally between 30 and 50. The right basement humidity and how to measure it, setting up a continuous drain, and if the unit is undersized, the sizing calculator.

A hygrometer at chest height in the middle of the room gives the number; a flashlight along the lowest corners and behind stored boxes gives the story. A musty smell with dry walls usually means the air needs drying. A tide line, damp carpet edge or soft drywall means water came in, and the question becomes where from: finding a hidden leak and the moisture meters that read through paint without a hole.

The summer floods we get called to have one thing in common: the power went out in the storm and the pit filled while the primary pump sat silent. A battery backup pump tested under load, or a water-powered backup if the house has municipal pressure, is the fix. A portable generator helps only if someone is home, awake, and able to start it in the rain.

Bucket test again, and make sure the high-water alarm actually sounds. Then go outside and follow the discharge line: it should not be crushed under a wheelbarrow, buried in mulch, or pointed back toward the foundation. A discharge line that cannot flow is the same as a dead pump.

New batteries in every leak sensor. Test the smart shutoff valve's automatic close from its app so you know it still moves. Add sensors in the places that flood only in a storm: the floor of the window wells and the base of the basement stairs.

Photograph every room and the mechanicals now, so that a claim later has a before. Then read the policy for two words: standard homeowner policies exclude flood (rising surface water needs a separate flood policy), and sewer or drain backup is usually an endorsement you have to add. Some insurers also discount premiums for leak detection; our table of water leak detector insurance discounts lists the programs we have confirmed. The claim checklist crews work from covers what to document when water does come in.

Know where the main shutoff and the breaker panel are, what you would move off the floor first, and who you would call. Drying that starts inside the first day or two is a cleanup; drying that starts later is a mold job. The first 72 hours of a flooded basement, how to dry wet carpet, and when wet drywall can be dried and when it has to come out.