Short definition

Hose-attached freeze rupture is the specific way a frost-proof sillcock fails when a garden hose is left attached during a freeze. The hose seals the spout, water can’t drain back to atmosphere, the long stem stays full, and freezing water ruptures the back end of the bib deep inside the wall. It’s the leading cause of “I have a freeze-proof and it still burst” calls every PNW winter.

What it is

A frost-proof sillcock works because the chamber between its valve seat (deep inside the wall) and the spout (outside) drains by gravity through the body when the handle is closed. Two conditions are required for that drain-back: the bib has to slope downward toward the outside, and the spout has to be open to air.

Leave a hose attached and the hose creates an air-tight seal at the spout. Water in the long stem can’t fall out because air can’t get in to replace it. The chamber stays full. When temperatures drop, that water freezes, expanding about nine percent, and ruptures the path of least resistance — usually the brass right at or just behind the valve seat. Discovery is delayed: the leak doesn’t show until someone next opens the bib in spring or the next time the temperature warms enough for ice to thaw and water to flow.

Why it matters to a homeowner

This is the single most common failure mode for “I have a frost-proof so I don’t need to do anything” homeowners. By the time water shows up on the basement ceiling or in a wall stain, the rupture has been leaking intermittently for weeks. Repair runs $250 to $1,500 depending on wall access and concealed water damage; the prevention is unscrewing one hose, which costs nothing.

Insurance generally covers the water damage as “sudden and accidental,” but not the bib replacement. Spring is when claims surface, and renters often don’t know to disconnect — which is why landlords end up holding the bag.

When a plumber says “you had a hose-attached freeze rupture,” that’s the diagnosis: the part worked correctly, the operator did not.

When you’ll encounter this term

  • A spring-thaw call to a plumber after a wall stain appears.
  • Your homeowner’s insurance adjuster’s notes after a water-damage claim.
  • The owner’s manual for any Woodford, Prier, or Mansfield sillcock — they all warn against attached hoses in freezing weather.
  • The reason “winterize before first freeze” is in every PNW homeowner’s October checklist.

Common variants

  • Hose-attached freeze rupture (this entry) — frost-proof bib failed because of attached hose.
  • Standard hose bib freeze rupture — happens with or without a hose, because there’s no drain-back mechanism at all.
  • Improper-slope failure — frost-proof bib installed level or sloping toward the house. Drain-back fails on its own. Less common than hose-attached.

Washington note

PNW freeze cycles are uniquely tricky because they often follow mild falls. Halloween is warm, the homeowner doesn’t think to winterize, and a December cold snap arrives with hoses still on every bib. Spokane and east-of-Cascades cities have more sustained freezes, but Puget Sound’s abrupt freezes after warm spells produce more burst-bib calls because owners are caught off guard. The October-15 hose-disconnect rule is what every WA plumber recommends regardless of where you live.