Frozen pipes: prevention, thawing and burst pipes

Checked against FEMA and other official sources · Last reviewed October 8, 2026

At what temperature do pipes freeze?

There is no single number. Two Texas government sources use 20°F as a warning line for pipes in unheated spaces; we did not find a federal standard. In a guide written for homeowners in the South, Texas A&M AgriLife Extension says water pipes "have the potential to freeze and burst when the outside temperature reaches 20 °F or below."

The City of Horseshoe Bay, Texas, says problems begin when temperatures fall into the teens and calls 20°F the "temperature alert threshold." It explains why the number is below freezing: - An unheated part of a house, such as an attic, is almost always at least a few degrees warmer than the outdoors. - Water "supercools" several degrees below freezing before ice begins to form. In University of Illinois research tests, pipes in an unheated, insulated attic consistently started forming ice when the outdoor temperature dipped just below 20°F.

The threshold is not a guarantee. Horseshoe Bay warns that pipes exposed to cold air because of cracks in a wall, missing insulation or an outdoor location can freeze when it is warmer than 20°F. That is especially common in some manufactured homes and older homes that sit above the ground.

The pipes most at risk, according to Texas A&M AgriLife Extension, are outdoor hose bibs, swimming pool and sprinkler supply lines, and water pipes in basements, crawl spaces, attics and garages, or against exterior walls with little or no insulation. A hot water line can freeze too if water isn't moving through it. [1][2]

How to prevent frozen pipes

Before cold weather: - Insulate pipes in unheated or drafty areas such as attics, garages and crawl spaces. Pipe insulation comes in foam or fiberglass sleeves. - For pipes that tend to freeze even when insulated, Bellevue Utilities says electrical heat tape may help. Texas A&M AgriLife Extension recommends UL-listed heat tape or heat cable, and Horseshoe Bay suggests one with a built-in thermostat; follow the maker's instructions. - Seal leaks in crawl spaces and basements. - Disconnect and drain garden hoses. Close inside valves that feed outdoor faucets if you can, and cover hose bibs. - Drain swimming pool and sprinkler supply lines following the manufacturer's or installer's directions. Texas A&M AgriLife Extension says not to put antifreeze in these lines.

During a freeze: - Let faucets served by exposed pipes drip. Bellevue Utilities says running water through the pipe, "even at a trickle," helps prevent freezing. Horseshoe Bay adds that if ice does form, an open faucet lets water escape before pressure builds to the point where a pipe can burst. - Open kitchen and bathroom cabinet doors so warm air can reach the plumbing. - Keep garage doors closed if water lines run through the garage. - Keep the thermostat at the same temperature day and night.

Never try to heat your home with a gas stovetop or oven. Ready.gov warns that it risks carbon monoxide poisoning, fires and burns. [1][2][3][4][5]

If you'll be away: thermostat settings and vacant homes

Official guidance differs on how low you can set the heat when you leave: - Texas A&M AgriLife Extension and Bellevue Utilities say to set the thermostat no lower than 55°F if you go away during cold weather. - Austin Water says that if you will be away during freezing temperatures, turn off your water at the meter and set your thermostat to 65 degrees or higher.

For homes or buildings left unheated for a long time, Bellevue Utilities recommends winterizing: turn off the main shut-off valve, turn off the water heater, open indoor and outdoor faucets to drain the pipes, drain irrigation systems, and flush toilets to drain the tanks.

These steps also matter for insurance. See the insurance section below. [1][3][4]

How to thaw frozen pipes safely

A frozen pipe is likely if you turn on a faucet and only a trickle comes out, according to Bellevue Utilities. Then:

• Keep the faucet open. Texas A&M AgriLife Extension says water will begin to flow as you treat the frozen area, which helps melt more ice.
• Know where your shut-off is first. The pipe may already be cracked and will leak once it thaws.
• Apply gentle heat. Austin Water suggests "a hair dryer, electric heating pad or warm towels," starting at the faucet end and working back toward the wall. Texas A&M AgriLife Extension also lists a portable space heater and towels soaked in hot water, and says to keep electrical cords away from water.
• Never use an open flame. Texas A&M AgriLife Extension says not to use "a blowtorch, kerosene or propane heater, charcoal stove, or other open flame devices," because they are a serious fire hazard and release carbon monoxide.
• Keep going until full water pressure returns, then check other faucets. If one pipe freezes, others may too.

Not every utility agrees on electric heat. Bellevue Utilities recommends wrapping pipes in rags and pouring hot water over them, and says to never use "an open flame or electric device" to thaw frozen pipes because of fire or shock risk. Every source agrees on no open flames.

Call a licensed plumber if you can't find the frozen section, can't reach it, or can't get it to thaw. [1][3][4]

How to shut off the water to your house

Your main shut-off valve controls the flow of water into your home. Find it before you need it, make sure everyone in the house knows where it is, and keep it clear of debris.

Where to look: - Bellevue Utilities says the shut-off valve is commonly in the basement, the garage, or outdoors by the foundation, often near the front faucet. - Austin Water says the property owner's valve is typically on your side of the water meter, at the meter box.

If your home's valve is missing, broken or hard to find, you can turn off the water at the meter box in an emergency. Bellevue Utilities says to use a crescent wrench or meter valve key and turn the valve clockwise; Austin Water notes a meter key is sold at most hardware stores. If your valve is missing or broken, Bellevue says to have one installed or repaired. Renters should ask their property manager. Rules and equipment vary, so check with your own water utility. [3][4]

What to do if a pipe bursts

• Shut off the water. Bellevue Utilities says that if a pipe breaks, "immediately close the main shut-off valve to stop excessive flooding." If you don't have a working valve, turn the water off at the meter.
• Call a plumber or your property manager to repair it. Bellevue notes that property owners are responsible for repairing broken pipes on their property.
• Document the damage. Missouri's insurance regulator says to document damage as soon as it is safe, take photos before making temporary repairs, keep receipts for emergency fixes, and contact your insurance company promptly.

If water soaked floors, walls or furniture, drying quickly matters. See mold after water damage for the 24-48 hour drying window. [3][4][6]

Does insurance cover frozen and burst pipes?

Often, yes, if you took reasonable care. Missouri's Department of Commerce and Insurance says "a typical homeowners policy covers the repair of frozen pipes and the damage they cause." The NAIC, the association of state insurance regulators, says policies cover damage from a "sudden and accidental" discharge from a plumbing system.

The main exceptions involve heat and vacancy: - NAIC says policies generally require homeowners to keep the home at a minimum temperature, or shut off the water supply if the home is vacant. If your insurer decides you neglected your plumbing, the burst-pipe damage may not be covered. - Missouri says exceptions can apply when the home is vacant or under construction, "unless you use reasonable care to maintain heat in the building or shut off the water supply and drain the system and appliances of water." - In a 2021 bulletin issued after that February's winter storm, the Texas Department of Insurance said that whether a policyholder took reasonable care "must be based on the unique circumstances of the claim."

Policies differ, so read yours and ask your insurer or agent before winter if you'll leave a home empty. Water from a burst pipe is handled differently from flood water; see homeowners insurance and water damage and what flood insurance covers. [6][7][8]

Questions people ask