How to Winterize a House's Plumbing (Step-by-Step for Vacant and Seasonal Homes)
Winterizing a house's plumbing means choosing between two approaches early, then following through in the right order. A house completely empty for the whole season is usually worth draining dry, since that protects it even through a power outage or a hard freeze. A house checked periodically, or left for a shorter stretch, is often better served by keeping the heat on at a safe minimum instead. Either way, the traps, the outdoor faucets and the water heater each need their own attention, and a remote leak detector on the main line can confirm the plan actually held once you've locked up and left.
- Choose the dry method (a full drain-down) for a house that will be completely vacant all season, and the wet method (heat kept on at a minimum) for a home someone checks periodically or a shorter absence.
- Protect the P-traps and the toilet trap with propylene glycol antifreeze, never the ethylene glycol antifreeze made for car engines.
- Outdoor faucets and hose bibs need their own drain-down or an insulated cover, since they sit outside the heated part of the house.
- A water heater has its own gas or electrical shutoff sequence and isn't drained the same way as an ordinary supply line.
- Homeowners insurance typically expects either a minimum indoor temperature or a shut-off, drained system while a house sits vacant, so it's worth checking the actual policy.
Decide whether to drain the system dry or keep it warm
The right method depends less on the calendar and more on how empty the house will actually be, and on how much effort you're willing to spend reversing it later. An empty system can't burst from freezing, since there's no water left inside it to expand, which is why a full seasonal vacancy usually favors draining. A full drain-down and refill also takes real effort to reverse, which is why a shorter or periodically checked absence usually favors just keeping the heat on. The comparison below breaks the two down.
| Situation | Better approach | Why it fits |
|---|---|---|
| Empty for the whole winter, nobody checking in | Drain the system dry | No water left to freeze and expand, so the risk holds even through a power cut |
| Checked periodically, or away for a shorter stretch | Keep the heat on at a safe minimum | Avoids redoing a full drain-down and refill on every visit, and the home stays usable when someone does stop by |
If you're weighing a few days away rather than a full seasonal shutdown, see whether turning off the water before a shorter trip is worth doing. If the home stays occupied and you just want a single cold-snap checklist, the room-by-room frozen-pipe prevention checklist covers that instead. The rest of this guide assumes a full seasonal closure, either dry or wet.
Shut off the main line and drain the interior pipes
Once you've settled on the dry method, start at the main shutoff valve rather than at individual fixtures, so no more water can enter while you work. If you're not sure where that valve is or how it operates, the step-by-step guide to shutting off the water to your house covers finding and turning it; this article assumes it's already closed. From there, open the highest fixture in the house, such as a top-floor bathtub or shower, and the lowest, such as a basement laundry tub or an outdoor spigot, so gravity pulls water down and out of the pipe runs between them, and leave both open until the system finishes draining.
What to do about lines that won't drain by gravity alone
Gravity empties most of a house's plumbing, but some sections hold water regardless, especially horizontal runs with a dip or a low point that isn't near an open fixture. For those, the usual approach is to disconnect the pipe unions or joints closest to the main valve so the trapped water has somewhere to go, or to blow the remaining water out with compressed air fed in at an accessible point (source: Purdue University Extension). If you're not confident which joints are safe to open, or how much air pressure a line can take, bring in a plumber rather than force apart a connection that wasn't meant to come apart.
Protect the traps without using the wrong antifreeze
A P-trap under a sink and the trap built into a toilet base are shaped to hold a small amount of water permanently, which normally stops sewer gas from coming back up the drain. That's exactly the water left behind even after the rest of the system has been drained, and if it's allowed to freeze it can crack the trap rather than simply block it. The fix is to replace that trapped water with antifreeze rather than leave it alone or try to blow every last drop out.
The antifreeze that belongs in a home's plumbing is propylene glycol, sold as RV or plumbing antifreeze, which is non-toxic and gentle on the materials and seals used in household water systems (source: Camping World). The antifreeze used in a car's cooling system is a different chemical, ethylene glycol, and it has no place in any part of a home water system: it's toxic, and using it can contaminate the system and damage plumbing components (source: Purdue University Extension). Check the label before you buy it; if it doesn't say propylene glycol, RV or plumbing use, it isn't the right product for this job.
For an accessible sink drain, pour about 1–2 cups of RV antifreeze straight down (source: Camping World). The same principle covers every other trap in the house, including the toilet's: pour in enough antifreeze that it displaces the water the trap normally holds, since that displaced water is what actually prevents the freeze, not any fixed volume. A toilet's built-in trap holds more water than a sink's P-trap, so it needs more than the sink amount, in the same pint-to-quart range Purdue University Extension gives for a generic trap you can't measure directly, scaled toward the higher end for a toilet, or you can blow the water out with compressed air instead (source: Purdue University Extension).
Handle outdoor faucets, hoses and exposed lines
Hose bibs and outdoor faucets sit outside the heated part of the house, so they freeze before anything on the inside does. Start by disconnecting every garden hose and draining what's left inside it before storing it for the winter; a hose left attached can trap water against the faucet and keep it from draining fully. If the faucet itself isn't a frost-free type, close its interior shutoff valve, then open the outside spigot and leave it open until the section between the valve and the spigot has emptied (source: Travelers). Where there's no separate interior shutoff for that line, fit an insulated faucet cover instead.
Don't forget the water heater needs its own procedure
A water heater isn't just another length of pipe to drain. Before you touch its drain valve, the gas supply or the electrical circuit needs to be shut off in a specific sequence, and getting that wrong is a safety issue rather than a plumbing inconvenience. That sequence belongs to the dedicated guide to shutting off a water heater safely, which covers both gas and electric units; this article deliberately stops at flagging the boundary rather than repeating those steps here. Treat the water heater as its own item on the winterizing list, not a step folded into draining the rest of the house.
If you're keeping the heat on instead, do it properly
The wet method is about maintaining conditions rather than carrying out a procedure. Keep the thermostat at a minimum of about 55°F (13°C) while you're away, since that's generally enough to keep the wall and floor cavities around the pipework above freezing even during a cold snap (source: Travelers). Insulate any pipe runs that pass through unheated spaces, such as a garage, basement or attic, and consider UL-listed heat tape on interior metal pipes that run along an exterior wall, since those sections are most exposed to outside temperatures (source: Travelers). It also helps to open the cabinet doors under sinks on exterior walls, so warm air can reach the pipes behind them.
Know what your insurance actually expects
Winterizing correctly isn't only about avoiding the mess of a burst pipe; it can also decide whether your insurance actually pays for the damage. Homeowners policies generally cover water damage from a frozen, burst pipe on the assumption that the homeowner took reasonable steps to prevent the freeze in the first place, and a claim can be denied if the insurer finds the plumbing was neglected while the house sat empty (source: NAIC). That usually means the policy expects one of the two approaches covered here, heat kept on at a minimum or the system shut off and drained, and a given policy may specify which one it wants (source: NAIC). Treat this as a reason to check your own policy or ask your insurer, not as insurance advice in itself.
Add remote monitoring so you're not just hoping it held
Whichever method you use, most of the season passes with nobody physically standing in front of the pipes to confirm anything. That's the gap a whole-house leak detector installed on the main line is built to close. Hydrion's smart whole-house water leak detector with an automatic shut-off valve sits on the main line and can flag flow that doesn't match the pattern of a closed-up, empty house, closing its valve automatically when that happens. From the companion phone app, you can check current flow, temperature and valve status, or close the valve yourself, without a trip to the property. For the fuller picture of how this category of device works before deciding whether one fits your setup, the guide to how smart water leak detectors and auto shut-off valves work covers the mechanics, and if you already have one on hand but haven't installed it yet, the installation guide walks through fitting it to the main line.
It's worth being precise about what this adds. What a shut-off valve can't do is thaw a pipe that's already frozen solid: a frozen line doesn't move water at all, so it won't register as abnormal flow until it thaws or the ice pressure cracks it. The value here is catching a flaw in the winterizing you already did, rather than replacing the need to do it.
None of these steps individually take long, but skipping one, an overlooked outdoor faucet, an untreated trap, a water heater treated like an ordinary pipe, is usually what turns a routine seasonal closure into a repair bill. Work through the drain-dry-or-keep-warm decision first, follow through on the method that fits your situation, and use remote monitoring as the way you confirm it held rather than as a reason to skip a step.