Most people who own a second place down the shore have the same October moment. You lock the door on a Sunday afternoon, look back at the house, and think, "I'm pretty sure I got everything." Then in February you get a text from a neighbor about water coming out from under your garage door.

That gap between "pretty sure" and "actually done" is where almost every expensive winter surprise lives. Frozen pipes. A dead sump pump. A roof that was fine in September and not fine after the first nor'easter.

So here is the version of the list we would go through if we were sitting at your kitchen table with a cup of coffee, in the order we would actually do it.

Start with the water, because water is what wrecks houses

Water damage is the most expensive thing that happens to a closed-up house over the winter, and it is also the most preventable.

Shut off the main. Find the main valve and close it. Tag it clearly so anyone who needs to reach it in a hurry can find it without having to hunt.

Drain the lines. Open every faucet, upstairs and down, plus the tub spouts. Flush every toilet. Drain the water heater or at least shut it down according to the manufacturer's instructions. Open the drain valve at the lowest point in the house if you have one.

Do not forget the outdoor shower. This is the one that gets overlooked most often at the shore. Outdoor showers, outside spigots, and foot rinses hold water in the line, and that line usually runs through an unheated wall. Find the inside shutoff valve for it, close that, then open the outside faucet and let the line drain. Disconnect and store the hoses.

Blow out the irrigation. If you have a sprinkler system, have it professionally blown out. It costs very little compared to replacing cracked lines and heads in the spring.

Add antifreeze to the traps. Pour RV antifreeze into sink, tub, and toilet traps. It keeps the water in the trap from freezing and cracking the pipe, and because it does not evaporate the way water does, the trap stays sealed and sewer gas cannot come up into the house.

Put in water sensors. If you are leaving the water on, put cheap Wi-Fi leak detectors under the sinks, near the water heater, and by the washer. They will text you before a slow leak becomes a floor replacement. They need power and internet to work, so this only helps if you are leaving both on.

If you leave the heat on, leave it on correctly

Some owners fully drain the house and shut everything down. Others leave the water on and keep the heat running low. Both approaches work. The trouble comes from doing half of one and half of the other, such as leaving water sitting in the pipes and relying on a furnace that nobody is checking on.

If you are keeping the heat on, set it around 55 degrees rather than 45. That extra ten degrees is your cushion, because the air inside a wall or a cabinet on an exterior wall runs colder than whatever the thermostat reads in the hallway. Open the cabinet doors under the sinks so warm air can reach those pipes.

Then make sure you would actually find out if the heat went out. A smart thermostat that can alert your phone when the inside temperature drops is where the money is well spent here. The same goes for filling the oil tank or scheduling a propane delivery before the first cold snap rather than after it.

The sump pump and the crawl space

If your place has a sump pump, test it before you leave. Pour a bucket of water into the pit and make sure it turns on and clears the water. Check that the discharge line is clear and pointed away from the foundation.

Then ask the harder question: what happens if the power goes out during a storm, which is exactly when you need the pump most? A battery backup or a water-powered backup pump is the difference between coming back to a damp crawl space and coming back to a restoration bill.

While you are down there, look for standing water, insulation that has fallen, and any gap a mouse could squeeze through. Mice only need about a quarter inch. Pack those gaps with steel wool, which they will not chew through, then seal over it with expanding foam. A quiet, empty house is exactly what they are looking for in November.

Outside, before the wind arrives

Gutters and downspouts. Clean them out. Clogged gutters send water down the siding and into the foundation, and ice makes it worse.

Roof and flashing. Walk the perimeter and look up. Lifted shingles, loose flashing around chimneys and vents, and a soft spot in the fascia will all get worse between November and March.

Trim the trees. Anything hanging over the roof should come down now. For branches near the power lines, call the utility rather than handling it yourself.

Furniture, grills, and umbrellas. Store them inside or secure them. Shore wind is strong enough to put a patio chair through a window.

Flood vents and grade. If you are in a flood zone, make sure your foundation vents are clear and functioning. Check that the ground still slopes away from the house.

Docks, bulkheads, and lifts. Pull floating docks if that is your setup, remove dock boxes and ladders, and get the boat lift serviced or raised out of the water. Walk the bulkhead at low tide while you can actually see it. You are looking for a leaning or separating cap, gaps between the boards, and any spot where the soil behind it is washing through. Small gaps in the fall become sinkholes in your yard by spring.

Storm protection. If you own shutters or panels, dry-fit them in October, not the day before a named storm. Label them by window.

Inside, before you lock up

Empty the refrigerator and prop the doors open, or leave it running if you plan to visit. Take out anything that can freeze or attract pests, including canned goods and pantry items. If the house holds humidity, run a dehumidifier with a hose to a drain so it does not fill up and shut off. A closed house with no air moving is how mold ends up on the closet walls by spring.

Set a few lights on timers. Forward the mail or have someone collect it. Arrange snow removal ahead of time, both so you are not scrambling in January and because an unshoveled driveway in front of a dark house signals that nobody is around.

If you rent the place, add these

Take dated photos of every room after the last tenant leaves. This is your baseline for spring.

Do the deep clean and any repairs now, while contractors still have availability. Everyone tries to get the same work done in April, and by then the good ones are booked into June.

Review the insurance policy language, specifically what it says about vacancy or unoccupied periods and what it requires of you. Many policies have conditions about maintaining heat or shutting off water. Call your agent and ask them directly rather than assuming.

Confirm your flood policy renewal date and make sure it does not lapse over the winter.

Set your rates and get your listing live. Serious renters start booking summer weeks in January and February.

DRG point of view

The owners who have the smoothest winters are not just the thorough ones. They are the ones who have somebody local putting eyes on the house.

Find a caretaker, a neighbor, a handyman, or a property manager. Pay them to walk through the house after every significant storm and once a month otherwise. Give them a key, show them where the main water shutoff is, and make sure they have your cell number. That arrangement usually runs a few hundred dollars for the season, and it catches what a checklist cannot: the branch that came through a screen, the neighbor's downspout now emptying against your foundation, the back door that blew open.

We will also say this plainly. If you are thinking about selling in the spring, the condition the house sits in all winter is going to show up in your April photos and in your inspection. Buyers pick up on a musty smell and a water line on the crawl space wall long before they notice the countertops.

One last thing

Write your own version of this list, specific to your house, and keep it in a drawer near the door. Add to it every year when you find something you forgot. In about three seasons you will have something better than any generic checklist, because it will be about your house, your pipes, and your particular outdoor shower that never fully drains.

Then closing up in October takes an afternoon instead of a weekend of second-guessing.