Winter Absences: Getting Your Pipes Ready Before You Leave
Water expands by roughly 9% when it freezes. Inside a closed copper, PEX, or PVC pipe, that expansion creates extreme hydrostatic pressure—often exceeding 2,000 pounds per square inch—causing the pipe wall to split. The most severe damage typically occurs not when the pipe freezes, but hours or days later when the ice thaws and water flows into an empty home.
If you are leaving a house unoccupied during cold-weather months, here is how to prepare plumbing and heating systems before departure.
1. Maintain the 55°F (13°C) interior temperature baseline
A common mistake during winter travel is turning off the central heating system completely to save on utility bills.
- Temperature standard: The Insurance Institute for Business & Home Safety (IBHS) and the Federal Emergency Management Agency (FEMA) advise maintaining interior building temperatures at no lower than 55°F (13°C) during winter absences.
- Why 55°F matters: While 55°F feels cool in the center of a living room, temperatures inside perimeter walls, floor joists, uninsulated crawlspaces, and enclosed under-sink cabinets can be 15°F to 20°F colder than the ambient room reading. Keeping the central living area at or above 55°F helps warm air radiate into exterior wall cavities.
- Thermostat battery check: If your wall thermostat relies on alkaline batteries rather than power from the furnace wiring, install fresh batteries before leaving so the heating system does not drop offline unexpectedly.
2. Shut off the main water supply and drain the lines
If water cannot enter the home, a pipe freeze cannot turn into an uncontrollable interior flood.
- Locate and close the main valve: Turn off the main water shutoff valve where water enters the residence (typically in a basement, crawlspace, or utility room). Turn gate valves clockwise until snug, or turn quarter-turn ball valves perpendicular to the pipe.
- Drain the vertical plumbing stacks:
- After closing the main valve, turn on the faucets at the highest level of the house (such as an upstairs bathroom).
- Open the faucets at the lowest level of the house (such as a basement laundry sink or garden spigot).
- Allow water to drain completely by gravity, then leave faucets slightly open to relieve pressure if residual moisture expands.
- Exceptions (boilers and fire sprinklers): If your home heats using a hydronic radiant heating system or boiler that requires an active water feed, or has an automated residential fire sprinkler system, do not shut off the primary supply without consulting a heating contractor or fire technician. In those homes, shut off individual supply stops to sinks, toilets, and appliances instead.
3. Under-sink cabinets and interior airflow
- Open under-sink cabinet doors: Kitchen and bathroom sinks frequently sit against exterior walls. Open all cabinet doors below sinks so warmer room air can circulate freely around the supply lines and traps.
- Keep interior doors ajar: Leave bedroom, bathroom, and utility closet doors open throughout the house to allow balanced warm air circulation between rooms.
- Insulate exposed pipes: Wrap exposed water lines located in unheated basements, crawlspaces, attics, or garages with foam pipe insulation sleeves or fiberglass wrap. While insulation does not generate heat, it slows thermal transfer during sudden cold snaps.
4. Exterior spigots and hose bibbs
- Disconnect all hoses: Leaving a garden hose attached to an outdoor spigot traps water inside the fixture. Even frost-free sillcocks will freeze and split inside the exterior wall if a hose remains connected.
- Drain exterior lines: If your home has dedicated interior shutoff valves for exterior hose bibbs (common in cold climates), close the interior valves and open the outdoor spigot to drain remaining water. Open the small bleeder cap on the interior valve over a bucket to clear the line.
5. Appliances and plumbing fixtures
- Water heater: Switch electric or gas water heaters to "Vacation" mode or set the temperature dial to its lowest setting. Do not drain the water heater unless the electrical breaker is shut off and gas supply is closed, as heating elements burn out quickly in an empty tank.
- Washing machine: Turn off the hot and cold supply taps behind the washing machine; rubber supply hoses are under constant pressure and can rupture during cold weather.
- Refrigerator ice maker: Turn off the automatic ice maker switch or lift the feeler arm so the unit does not continuously cycle when the water supply is off.
- Plumbing traps and toilets (severe cold): If prolonged sub-freezing weather is anticipated or heating power could be interrupted:
- Flush toilets after shutting the main valve to empty the tanks.
- Pour non-toxic RV/marine plumbing antifreeze (propylene glycol) into toilet bowls, sink P-traps, and floor drains to displace standing trap water. Never use automotive engine antifreeze (ethylene glycol), which is toxic to domestic pets and municipal waste systems.
Away Mode includes a practical home preparation checklist to run through before you depart.
Sources and primary references
- Insurance Institute for Business & Home Safety (IBHS), Freezing Pipes Prevention and Mitigation Standards (ibhs.org).
- Federal Emergency Management Agency (FEMA), guidance on freezing weather and pipe bursts (fema.gov).
- American Red Cross, Preventing and Thawing Frozen Pipes Guide (redcross.org).
- Consumer Product Safety Commission (CPSC), Winter Home Safety and Freeze Prevention Guidelines (cpsc.gov).