Last Updated: October 26, 2026
Quick Summary
Plumbing for winter means insulating exposed pipes in crawlspaces, garages, attics and exterior walls, winterizing outdoor faucets, and disconnecting garden hoses before the first freeze. Pipes typically begin to freeze when outdoor temperatures drop to 20°F or below, especially when the cold lasts several hours.
- Foam sleeves are the easiest insulation choice for most homeowners and resist moisture.
- Close the indoor shut-off valve, drain the outdoor faucet, then leave it open.
- Disconnect and drain every garden hose before the first freeze to prevent splits.
- Regulate irrigation blow-outs to roughly 50 psi or less to avoid rupturing valves and fittings.
- Vacant homes need the main shut off, lines drained and blown out, plus plumbing-safe antifreeze in traps.
Table of Contents
- What Temperature Do Pipes Freeze?
- How to Insulate Water Pipes Before the First Freeze
- How to Winterize Outdoor Faucets and Hose Bibs
- Draining Pipes, Water Heaters, and Appliances
- Sealing Cracks and Air Gaps That Let Cold Air Reach Pipes
- How to Winterize Plumbing in a Vacant House
- What to Do if a Pipe Freezes or Bursts
- Book Your Pre-Winter Plumbing Inspection
- Frequently Asked Questions
What Temperature Do Pipes Freeze?
Plumbing for winter starts with knowing that pipes typically begin to freeze when outdoor temperatures drop to 20°F or below, especially when that cold lasts for several hours.
Here is the part most homeowners get wrong. A pipe does not burst when the water inside freezes solid.
The National Weather Service cold safety guidance puts it plainly: sustained cold, not one cold night, is what causes the most damage.
How to Insulate Water Pipes Before the First Freeze
Plumbing for winter begins with insulation, the cheapest insurance you can buy.
Start with the exposed pipes you can actually reach. Focus on any pipe that runs through an unheated space.
A simple method that works:
- Measure the pipe diameter before you buy sleeves.
- Slide the foam sleeve over the pipe and press the seam closed.
- Wrap pipe tape every foot or so to hold it.
- Pay extra attention to elbows and joints, where cold gets in.
- Leave a small gap at the water heater’s pressure relief valve.
Fiberglass vs. Foam Insulation Sleeves
Foam sleeves are the easier choice for most homeowners. They slide on fast, resist moisture, and need no gloves or wrapping.
Fiberglass wrap costs less per foot but takes more care. You must wear gloves and a mask, and you must seal it fully so it does not trap moisture against the pipe. Trapped moisture leads to rust.
How to Winterize Outdoor Faucets and Hose Bibs
Outdoor faucets and hose bibs are the first things to freeze, and often the first to cause a leak inside the wall. Winterizing them takes about ten minutes per faucet.
- Close the shut-off valve inside the house that feeds the outdoor faucet.
- Open the outdoor faucet to let trapped water drain out.
- Leave the outdoor faucet open so any leftover water can expand.
- Install an insulated faucet cover over the spigot.
- Check for drips or leaks before the cold sets in.
If your outdoor faucet has no indoor shut-off valve, a foam cover is your main defense. It helps, but it is not a guarantee in a hard freeze.
Disconnecting and Storing Garden Hoses
A hose left connected traps water in the faucet and the line behind it. That trapped water freezes and splits the pipe.
So disconnect every garden hose before the first freeze. Drain each one, coil it, and store it indoors or in a shed. This one step prevents a surprising number of winter leaks.
Draining Pipes, Water Heaters, and Appliances
Draining is not one task. It is a set of small tasks, each with its own sequence and its own way to go wrong.
You do not need to drain the whole house unless it will be vacant. For an occupied home, drain only the fixtures and appliances that sit in cold zones: an unheated laundry room, a garage utility sink, a seasonal cabin kitchen, a basement bar sink.
Water heater
Flush sediment before winter, not during it. Sediment insulates the burner or element from the water, so the tank works harder and recovers slower exactly when demand is highest.
While you are there, check the anode rod. It is the sacrificial metal that corrodes so the tank does not.
If the water heater sits in an unheated space and the home will be vacant, close the cold inlet, open a hot faucet, and open the drain valve until the tank empties.
Washing machine
Disconnect both hoses at the wall, not just at the machine. Water sits in the hoses and in the inlet screens. Drain the hoses into a bucket, then tip the machine slightly if the manual allows it to move residual water out of the pump. Leave the lid or door open so the drum dries.
Dishwasher
Run a cycle to clear the line, then shut off the supply valve under the sink if the unit sits against an exterior wall or in a cold zone. If the dishwasher has a drain hose that loops high under the cabinet, that loop holds water. A short blow of air through the drain line, or a cycle run with the supply off, moves most of it.
Irrigation lines and exterior spigots
Irrigation is the most overlooked system on the property. Blow it out with an air compressor before the ground freezes, and do it zone by zone. The compressor must be regulated. Most residential irrigation systems are designed for roughly 50 psi or less at the blow-out point, and pushing more can rupture valves, fittings, and backflow assemblies.
P-traps under sinks
A P-trap holds a cup or two of water year-round. In a cold room, that water freezes and cracks the trap or the tailpiece. For an occupied home, keep the room above freezing and run the faucet briefly each week. For a vacant home, empty the trap or protect it with plumbing-safe antifreeze, covered below.
Never blow compressed air into a closed system with fixtures still connected. Close or disconnect supply valves to fixtures first, and never exceed the pressure rating on the lowest-rated component in the line.
Drain in this order: water heater, then appliances, then irrigation, then traps. Water flows downhill, so start high and work low.
Sealing Cracks and Air Gaps That Let Cold Air Reach Pipes
Cold air does more damage than cold pipes. A small crack near a supply line acts like a wind tunnel all winter.
Walk your home and seal these spots:
- Gaps around pipes where they pass through exterior walls.
- Cracks in the foundation and rim joist.
- Openings around dryer vents and outdoor outlets.
Use caulk for small gaps and expanding foam for larger openings. Keep the heat on, even in rooms you rarely use. A steady indoor temperature is freeze protection.
How to Winterize Plumbing in a Vacant House
A vacant house is a different job, and the most common expensive mistake is applying vacant-house steps to an occupied home. Shutting off the main supply in a home where people still live creates its own problems: no water, no heat from a boiler that needs makeup water, and a water heater that can run dry. Decide which situation you are in before you touch a valve.
| Situation | Main risk | What to do |
|---|---|---|
| Occupied home | Exposed pipes in cold zones | Insulate, seal air gaps, keep heat on, drip faucets during hard freezes |
| Vacant property | No heat, no water movement | Shut off main, drain lines, blow out, add plumbing-safe antifreeze |
| Seasonal cabin | Long freeze periods, no supervision | Full drain and blow-out, plus a check-in schedule |
Shutting off the main water supply and draining the system
Shut off the main valve first. Then open every faucet, hot and cold, top to bottom, so air can enter and water can leave. Open the drain valve at the lowest point in the house.
Open the water heater drain and let it empty. If the home has a boiler or a hydronic heating system, do not drain it without reading the manufacturer’s instructions; some systems require a glycol charge or a specific low-water cutoff procedure, and draining the wrong system can damage the boiler.
Blowing out the lines
An air compressor is the most reliable way to clear residual water from a vacant home’s lines, but pressure matters. Regulate the compressor to a low setting, commonly in the range of 30 to 50 psi for residential plumbing, and open one fixture at a time so air has a path.
Do not blow air through a system with the water heater still connected and full. Do not exceed the pressure rating of the lowest-rated component in the line.
Plumbing-safe antifreeze for drains and toilets
Use only plumbing-safe antifreeze, also called non-toxic antifreeze, and confirm on the label that it is rated for potable-water plumbing and drains. Never use automotive antifreeze in household drains or fixtures.
Pour a small amount into each P-trap, each toilet bowl, and the toilet tank. A cup or two per fixture is generally enough for a trap or bowl.
Antifreeze is not a substitute for draining. It protects the small amount of water that remains in a trap or bowl. It will not protect a line that is still full.
Before you leave
Set the thermostat to a low but above-freezing temperature if the home has power, and arrange for someone to check the property after the first hard freeze. A slow leak that would have been obvious in an occupied home can run for weeks in a vacant one.
The decision is the safety step: occupied homes get heat and insulation, vacant homes get drained and blown out. Mixing the two is how properties flood.
What to Do if a Pipe Freezes or Bursts
A frozen pipe is not a disaster yet. A burst pipe is. The difference is how fast you act.
If a pipe freezes:
- Shut off the main water supply.
- Open the nearest faucet so melting water has somewhere to go.
- Warm the pipe gently with a hair dryer, starting at the faucet end.
- Never use an open flame or a torch.
If a pipe bursts, shut off the main valve first, then call for help. Learn what emergency plumbing service involves before you call.
Book Your Pre-Winter Plumbing Inspection
At AllSet Home, we offer upfront, flat-rate pricing, so you know the cost before we start. Schedule your pre-winter plumbing inspection today. Our licensed, background-checked technicians walk your home with our Aero Walkthrough and leave it cleaner than we found it.
Frequently Asked Questions
Will my pipes freeze if my heat is set to 65°F?
Setting the thermostat to 65°F or higher usually keeps interior pipes above freezing, but it does not protect pipes in unheated spaces like crawlspaces, garages, or exterior walls. Cold air can still reach those pipes even when the house feels warm. Keep cabinet doors open under sinks on exterior walls, and insulate any exposed runs. If you leave for an extended trip, maintain the heat rather than shutting it off, and ask a neighbor to check the house.
At what temperature should you let faucets drip?
Let a faucet drip when overnight lows are forecast to drop to 32°F or below, especially for faucets on exterior walls. A slow trickle, not a full stream, relieves pressure inside the pipe and makes a freeze less likely to burst it. Open both hot and cold sides. The small extra cost on your water bill is far less than a burst-pipe repair, and you can stop the drip once temperatures climb back above freezing.
How do you winterize outdoor faucets and hose bibs?
Disconnect and store all garden hoses, then shut off the indoor valve that feeds each outdoor faucet. Open the outdoor spigot to let residual water drain out, and leave it open if your fixture is a frost-free type. Install an insulated faucet cover over the spigot, and seal any air gaps around the pipe where it enters the wall. If you have an irrigation system, blow out the lines with an air compressor before the first hard freeze.
Should you shut off the water when leaving home in winter?
For a vacant or unoccupied property, shutting off the main water supply and draining the lines is the safest option, since no one is there to catch a leak. For a short trip in an occupied home, keep the heat on at 65°F or above and leave cabinet doors open instead. If you do shut off the main valve, drain the pipes and add plumbing-safe antifreeze to drains and toilets so traps and bowls do not crack.
Winter always finds the weak spot in a plumbing system, whether that is an unprotected hose bib or a water heater that has been limping along for years. AllSet Home can help you get ahead of it with upfront, flat-rate pricing, 24/7 emergency response, and licensed, background-checked technicians who fix it right the first time. Get started with AllSet Home and head into the cold season with plumbing you can trust.
