When temperatures drop below freezing, exposed or poorly insulated pipes can freeze. Before a cold snap, disconnect outdoor hoses, close and drain exterior lines where the plumbing allows it, insulate vulnerable pipes, seal drafts, and keep the building heated. If a pipe freezes or bursts, shut off the water if you can do so safely and call for help.
Focus on pipes in garages, crawl spaces, basements, attics, and cabinets along exterior walls. A building’s layout and pipe condition affect its risk. Related reading: pipe repair signs.
Why burst pipes are a problem in freezing temperatures
Freezing can create an ice blockage and trap pressure elsewhere in the line. A weak pipe, fitting, or connection may split, then release water when the ice thaws and flow returns. For an active leak or backup, call anytime to confirm current emergency availability.
A split pipe can release water into walls, ceilings, floors, and cabinets. The damage may begin when the ice thaws and water starts moving again. Check coverage on Pioneer’s Edwardsville service page.
A shutoff limits new water entering the damaged line. Know where the main shutoff is before cold weather arrives, and keep the path to it clear.
Insulation and steady indoor heat reduce exposure. Use materials made for the pipe and location, and follow the manufacturer’s instructions for any listed heat cable.
Preparation lowers the risk, but it cannot remove every risk from hidden piping, power loss, equipment failure, or a sudden temperature drop.
Understanding how pipes freeze and burst
An ice blockage can trap liquid water between the blockage and a closed point in the plumbing. As pressure rises in that trapped section, a weak area can split somewhere other than the visible ice. These conditions increase the risk:
- Ice blockage and trapped pressure: Freezing can block a line while liquid water remains trapped elsewhere. Pressure in that section can split a fitting or weakened pipe.
- Exposure to unconditioned air: Pipes in garages, attics, crawl spaces, unheated basements, and exterior-wall cavities can lose heat faster than piping in conditioned rooms.
- Missing or damaged insulation: Gaps, compression, moisture, or the wrong product can reduce the insulation’s protection around vulnerable pipe.
- Cold-air paths: Openings around utility penetrations, framing, doors, or windows can direct outdoor air toward otherwise interior piping.
- Previous freeze history: A line that froze before may still follow the same exposed route or contain a low area that needs property-specific correction.
- Duration and severity of cold: A longer or colder event, loss of heat, or power failure can expose piping that remained usable during a shorter freeze.
These factors help identify which pipes need attention first. Start with exposed supply lines and pipes that have frozen before.
Signs of possible burst pipes
A frozen pipe may not be visible. Changes in water flow, pipe shape, sound, or moisture can signal a problem before or after a thaw.
Watch for these signs:
- Little or no flow: A sudden change at one fixture during freezing weather can indicate an ice blockage, although valves and other restrictions can cause a similar symptom.
- Visible frost: Frost on an exposed pipe identifies a cold surface and deserves caution, but it does not show where a blockage begins or ends.
- Visible water: Dripping, spraying, or new dampness can indicate a leak. Shut off the supply if it is safe and avoid disturbing the pipe.
- Bulging, splitting, or changed shape: Do not heat, flex, or strike a deformed pipe. A damaged section can release water when ice thaws.
- Water after a thaw: A concealed split may become apparent only when flow returns, so check vulnerable areas as temperatures rise.
- Repeated trouble at the same fixture: A line that loses flow during more than one freeze needs its routing, insulation, and surrounding air exposure evaluated.
If water appears, shut off the supply if you can do so safely. Do not use an open flame to thaw a pipe.
If a pipe is bulging, split, or inaccessible, leave it alone and call a plumber. Moving or heating it can release water suddenly.
Steps to prevent burst pipes
Complete these checks before the forecast reaches freezing temperatures:
- Insulate exposed pipes: Follow the insulation manufacturer’s instructions for pipes in unheated basements, attics, crawl spaces, and exterior walls.
- Seal appropriate air leaks: Use weatherstripping or a sealant listed for the specific location. Do not block combustion air, appliance vents, drainage openings, electrical clearances, or another required opening.
- Disconnect and drain outdoor hoses: Before the freeze arrives, be sure to disconnect and drain all outdoor hoses. Leaving hoses connected can trap water inside, leading to frozen pipes and potential bursts. Store them in a sheltered area or garage for added protection.
- Keep the heat on: If you will be away during a freeze, leave the heating system running and follow your utility’s and insurer’s guidance for the lowest safe thermostat setting.
- Ask about vulnerable lines: If a pipe has frozen before, ask a plumber or the water utility whether a controlled drip is appropriate for that line and weather event.
Keep watching for reduced flow, bulging pipe, frost, or water after the thaw. A change in one fixture may identify a vulnerable branch before a larger leak develops.
Insulating exposed pipes
Pipe insulation slows heat loss from exposed piping. It is most useful when it fits correctly and the surrounding space is also protected from cold drafts.
Use this checklist to plan and inspect pipe insulation:
- Identify vulnerable runs: Trace piping through garages, unheated basements, crawl spaces, attics, exterior walls, and other spaces that lose heat quickly.
- Choose a listed product: Match insulation to the pipe size, material, temperature, moisture exposure, and location. Install listed heat cable only where its instructions permit.
- Measure before cutting: Fit sections to the actual pipe and account for elbows, valves, supports, and fittings without covering items that must remain accessible.
- Treat penetrations separately: Use the listed or fire-rated assembly required for the wall or floor. Ask a qualified trade about openings near utilities, electrical equipment, or combustion appliances.
- Close insulation seams: Fit and fasten the material as directed without crushing it, leaving gaps, or allowing it to slip away from the pipe.
- Inspect cold-air paths: Check doors, windows, vents, and exterior-wall cavities near the line, but preserve required ventilation and equipment clearances.
Insulation works with indoor heat and draft control. It does not warm a pipe by itself or protect a line during every outage or prolonged freeze.
Check the Completed Freeze Protection
- Confirm continuity: Look for open seams, uncovered fittings, compressed material, or sections that moved after installation.
- Keep controls accessible: Do not bury shutoffs, valves, cable controls, labels, or service points beneath insulation.
- Inspect listed heat cable: Follow its testing, overlap, clearance, and replacement instructions; never splice or improvise a repair.
- Protect the product: Replace wet, torn, crushed, or deteriorated insulation rather than assuming it still performs as intended.
- Watch the surrounding space: Verify that safe indoor heat can reach the area and that new drafts or open access panels have not changed conditions.
- Plan for outages: Know the water shutoff location and make a property-specific plan for extended loss of heat or power.
Keeping your home heated
Indoor heat helps protect piping that runs through conditioned space. Keep the building heated and make sure warm air can reach vulnerable plumbing.
- Maintain Safe Indoor Heat: Follow the heating-system manufacturer, utility, insurer, and property-specific guidance for occupied and vacant buildings. A setting merely above 32°F is not an adequate general recommendation.
- Use Listed Pipe Products: Install pipe insulation or heat cable rated for the exact pipe and location. Do not improvise with unlisted foam, rubber, fabric, lamps, heaters, or other combustible materials.
- Control Drafts Safely: Weatherstrip doors and windows and seal appropriate openings with products rated for the location. Preserve combustion air, vents, drainage, and required clearances.
- Refer Wall Work Appropriately: Missing wall or cavity insulation can involve fire blocking, vapor control, wiring, and moisture conditions. Have a qualified building or insulation professional evaluate that scope.
These measures reduce exposure but cannot guarantee protection. Hidden pipes, power loss, failed heating equipment, and prolonged cold can still create a freeze risk.
When to call a plumber
Before the forecast arrives, verify that the main shutoff is reachable and that everyone responsible for the property knows whom to call if flow stops or water appears.
If water flow drops suddenly, a pipe bulges, or water appears after a thaw, shut off the supply if safe and call Pioneer to confirm urgent availability.
Call before attempting to thaw an inaccessible pipe or any pipe near electrical equipment.
For a burst pipe or active leak, call anytime to confirm current emergency availability in Pioneer’s service area.