What breaks when a water line freezes, and where

Ice does not split a pipe by pushing outward where the ice is. It forms a plug, and the water trapped between that plug and a closed faucet downstream has nowhere to go as the plug keeps growing. Pressure in that short closed column climbs until the weakest point of the pipe lets go, often well away from any ice.

The failure is hydraulic, not mechanical

This is the part that surprises people who find the break: the split is frequently in warm pipe, feet from the cold spot that caused it. Once a plug seals the line, the freezing water behind it keeps expanding and drives pressure down the closed section toward the fixture. Copper, being ductile, usually opens as a clean longitudinal slit along the pipe wall, sometimes only an inch or two long and easy to miss until the system is repressurized. Rigid plastic supply pipe tends to shatter or crack circumferentially instead. Flexible tubing often survives the freeze itself and fails at a crimped fitting, where the tubing cannot expand and the joint takes the load.

It also explains why leaving a faucet cracked open works. An open fixture removes the closed end of the column, so as ice forms the displaced water has an escape and the pressure never builds. The moving water helps a little; the open end helps more.

The second surprise is timing. Very often nothing leaks while it is cold. The split is there, held shut by the ice inside it, and the house stays dry through the freeze. When temperatures climb back above freezing and the plug melts, the line repressurizes and the whole system starts discharging at once, through a break nobody has found yet.

1. You callOne number per county. The dispatcher takes the address, the ZIP and a short description of what happened.
2. A local crew calls backAn independent restoration contractor already working that county rings you directly and sets a time.
3. They look, then scope itNothing is priced from a phone call. The crew walks the building, takes readings, and writes a scope you can hand to your adjuster.

February 2021 in Baxter County, and what it did

Mountain Home took eight to ten inches of snow on February 14 and 15, 2021 and bottomed out at six degrees on the fifteenth, with the wider region running more than thirty degrees below average through February 20 as two snowstorms bracketed a long deep freeze. That length is what matters. A single cold night cools the air in a crawl space; a week below freezing cools the framing, the ground under the house and the pipe itself all the way through, and there is no daytime recovery to buy the line back.

The damage arrived on the thaw. As the same arctic outbreak began to release, water utilities across Arkansas reported waves of burst pipes hitting all at once. Hot Springs alone counted roughly three thousand homes and businesses with burst pipes, and the Washington Water Authority saw usage spike to 150 to 200 percent of normal as broken lines ran unnoticed. That is the shape of a freeze event: quiet for days, then a hundred failures inside a few hours, all competing for the same plumbers.

Why the lake houses take the worst of it

Baxter County's roughly 23,105 housing units skew toward retirees and second homes built around Bull Shoals and Norfork lakes, at Lakeview, Midway, Henderson, Clarkridge and along the shoreline roads. A large number of them are empty in February. A break in an occupied house is discovered in minutes by the sound. A break in a closed-up lake house discharges through a first-floor ceiling, down a stair, into a lower level, for however many days pass before someone drives out to check on it.

Power loss compounds it, and Baxter County has a history of that too. The January 26 to 28, 2009 ice storm laid one to two inches of ice on the Mountain Home area, the worst icing since December 2000, snapping at least thirty thousand utility poles statewide and cutting power to roughly 350,000 customers at the peak, with about a hundred thousand still dark by February 3. A house without power is a house without heat, and electric service in Mountain Home and Cotter is split between North Arkansas Electric Cooperative and Entergy Arkansas, so neighbors on the same street can be restored on different schedules.

The places a line freezes first

Freezing is a question of where the pipe sits relative to the heated envelope of the house, not how cold the night got. The order below is roughly the order these fail in a north Arkansas cold snap.

• Hose bibs and the short stub of pipe behind them, especially where a garden hose was left attached over winter and holds water against the valve.
• Supply runs in an unheated crawl space, where the insulation has fallen off the pipe or was never wrapped past the last elbow.
• Pipe in an exterior wall cavity on the north or west side, where insulation was packed behind the pipe instead of between the pipe and the sheathing.
• Lines in an unconditioned attic or garage, including the run to an icemaker or a second bathroom added later.
• Well houses and pump houses, where a single work light is often the only heat and one power outage ends it.
• Any fixture on a wall shared with an unheated space, such as a laundry sink on a garage wall.

What the water does to the house afterward

A supply break is clean water, which is the good news, and it stays clean for a limited time. Water running through insulation, over a dusty attic floor or across a subfloor picks up soil quickly, and water that has sat for several days in a closed house is no longer treated as a clean loss. That distinction changes what can be dried and kept.

The pattern of damage follows the framing rather than the room. Water from a ceiling break runs along the top of the drywall until it finds a light fixture, a vent boot or a seam, then drops in a place that has nothing to do with the pipe. It travels down stud bays inside walls, soaks the bottom plate, and shows up first as a dark line at the base of the wallboard. In a house with a crawl space it ends up on the vapor barrier and the ground below, where it will keep evaporating into the floor system for weeks unless it is removed.

Questions and answers

The sooner a dehumidifier is running, the shorter the list of things that have to come out.