After a Cold Snap: Finding Pipes That Split Without Telling You

A frozen pipe often doesn't leak while it's frozen. Ice expands, the pipe splits, and the ice plugs the crack. The leak starts when the line thaws, sometimes days later, and sometimes in a place nobody looks. Boise doesn't get long stretches of deep cold every winter, which is part of the problem: houses aren't always ready when a cold snap does come through.

Where splits usually happen

• Near crawl-space vents. Cold air pours in and lines close to the vent freeze first.
• Exterior walls. Kitchen and bathroom lines in outside walls, especially on the north side.
• Hose bibs. A frost-free hydrant with a hose still attached can trap water and split inside the wall, out of sight.
• Garages. Lines running through an unheated garage to a laundry room or water heater.
• Attics. Supply lines to an upstairs bathroom or an attic water heater.
• Sprinkler systems. Lines and backflow devices that weren't blown out in fall.

Right after a cold snap

• Check the meter with everything off. A moving meter after a thaw is a strong clue. How
• Walk the outside walls and look for water at the base or ice forming where it shouldn't.
• Look in the crawl space from the hatch if it's safe.
• Turn on each faucet. Low flow on one fixture can mean that line is still frozen.

If a line is still frozen

Open the faucet so water can move once it thaws, and warm the area gently. Never use an open flame. If you can't find or reach the frozen spot, that's a reason to call.

If water is already coming out

Close the house shutoff, then call. Leave the curb stop in the meter box to Veolia unless it's an emergency. Move valuables, take photos and keep notes for insurance.

Why the leak may not show upstairs

On crawl-space houses, water from a split line can run into the soil for weeks. Inside a wall, it can stay hidden until paint bubbles or a floor lifts. That's where a thermal camera and moisture meter earn their keep. Wall and ceiling leaks, crawl space leaks.

The bill side

A winter leak in Boise can raise the city sewer charge too, because that charge is based on readings taken between October and April. Why that happens.

Getting ready for next winter

Disconnect hoses in fall, close crawl-space vents during deep cold if that's how your house is set up, insulate or heat-tape lines near vents, get the sprinkler system blown out, and know where your house shutoff is before you need it.