Frozen pipes can leave a household without water and, if the pipe splits, cause serious damage after it thaws. Pipes in unheated garages, crawl spaces, cabinets against exterior walls and outdoor connections are particularly vulnerable during prolonged cold. Prevention starts before the forecast drops well below freezing.
Quick answer: Insulate vulnerable pipes, block cold drafts around them, disconnect outdoor hoses, keep the home heated and let warm room air reach plumbing in exterior-wall cabinets. During exceptional cold, a small drip at an at-risk faucet may help. Know where the main water shutoff is located.
Which pipes freeze most often?
- Outdoor hose bibs and irrigation lines
- Unheated garage, attic, basement and crawl-space pipes
- Plumbing routed through exterior walls with limited insulation
- Supply lines in cabinets where warm air cannot circulate
- Water lines exposed near foundation vents or unsealed penetrations
Both hot and cold supply lines can freeze. A pipe does not have to be outdoors to be exposed to dangerous temperatures.
7 ways to prevent frozen pipes
1. Disconnect hoses and protect outdoor fixtures
Remove hoses, drain them and shut off or drain outdoor lines using the correct procedure for your plumbing system. Frost-free faucets still need to drain and can be compromised by attached hoses.
2. Insulate exposed pipes
Use pipe sleeves or other materials suitable for the line and environment. Insulation slows heat loss but does not supply heat, so it may not protect indefinitely in an unheated space. Heat cable should be listed for the application and installed precisely as directed.
3. Seal cold-air leaks near plumbing
Look for gaps around utility penetrations, sill plates and drafty areas near piping. Seal appropriate openings without blocking required appliance combustion air or ventilation. In some homes, rerouting a vulnerable pipe into conditioned space is the best long-term fix.
4. Keep the heat on
Maintain a consistent indoor temperature during cold snaps. The American Red Cross recommends leaving heat on at no lower than 55°F when away during freezing weather. Homes with unusually exposed plumbing may need additional precautions even at that thermostat setting.
5. Open sink cabinet doors when needed
When pipes run along cold exterior walls, opening cabinet doors can allow room air to circulate. Remove household chemicals and other hazards from the reach of children and pets before leaving cabinets open.
6. Consider a controlled drip in extreme cold
If a particular pipe is known to be at risk, allowing a small flow of cold water through its faucet can reduce freezing risk. This uses water and is not a substitute for insulation or adequate heat, but it can be a temporary measure during severe weather.
7. Locate the main shutoff now
Make sure household members know where the main valve is and that it can be operated safely. If a line bursts, shutting off water promptly can prevent substantial additional damage.
How to tell if a pipe is frozen
A faucet producing only a trickle or no water during extreme cold is a warning sign, especially if other faucets work normally. You might also notice frost on exposed piping. Do not assume the absence of visible damage means the pipe is intact.
What to do if a pipe freezes
- Keep the affected faucet open to allow flow as the ice melts.
- Check for visible splits or leaks and be ready to shut off the main supply.
- If safe and accessible, apply gentle warmth with a hair dryer, warm towels or other approved low-temperature method.
- Never use a torch, open flame or improvised high-heat source.
- Call a licensed plumber if the pipe is inaccessible, damaged or will not thaw.
Frequently asked questions
At what temperature do pipes freeze?
There is no single guaranteed outdoor temperature. Risk depends on insulation, wind, exposure, duration of cold and how much heat reaches the pipe.
Do insulated pipes still freeze?
Yes. Insulation delays cooling but does not indefinitely protect pipes in a space that remains below freezing.
Should I shut off water when leaving for vacation?
Consider whether your plumbing, heating system and insurance requirements support that step. At a minimum, maintain heat and follow a winter vacancy checklist appropriate for the home.
Bottom line
Protect the vulnerable spots first and act early when severe cold is forecast. A few measures taken before the freeze can prevent a major plumbing emergency.