How a winter crack turns into a spring leak
- Fall
- The system is blown out, but the short section of pipe between the inside shutoff and the foundation wall still holds some water, or the inside valve is left partly open.
- Mid-winter cold snap
- Water in that pipe, or in the backflow preventer outside, freezes and splits a fitting. Nothing leaks because the valve is closed or the line is empty.
- April or May startup
- Someone opens the irrigation valve in the basement. Water flows to the cracked section, which may be inside a finished wall or soffit.
- Hours later
- Water runs down the inside of the foundation wall, soaks the bottom plate and insulation, and appears as a damp carpet edge or a stain on the drywall.
- Days later, if missed
- The cavity stays wet, baseboards swell, and a musty smell develops. This is when a small fitting repair becomes a wall tear-out.
Why it hides so well
The irrigation tap is usually near the water meter or main shutoff, often in a mechanical room, and the line then travels a short distance to exit through the foundation. In basements finished after the house was built, that line is frequently boxed into a soffit or buried behind drywall, so the cracked fitting is invisible.
Because sprinkler zones run on timers, the leak may also be intermittent. Water flows only while a zone is running, which can make the damp spot come and go and delay the moment anyone takes it seriously.
Where to look, and who repairs what
- Location
- Inside shutoff and drain valve
- Typical failure
- Cracked valve body or a drain cap left open
- Who repairs it
- Plumber or irrigation contractor
- Location
- Pipe through the foundation wall
- Typical failure
- Split copper or a failed fitting inside the wall cavity
- Who repairs it
- Plumber, then a restorer to dry the wall
- Location
- Backflow preventer outside
- Typical failure
- Cracked bonnet or body from freezing
- Who repairs it
- Irrigation contractor; testing requirements vary by water provider
- Location
- Zone valves and heads in the yard
- Typical failure
- Broken heads or lines underground
- Who repairs it
- Irrigation contractor; usually no interior damage
Questions to ask after an irrigation leak
- Was the damage limited to the time the system was running, and can the timer history show that?
- Does my water provider require a backflow test after the device is repaired or replaced?
- Should the irrigation line be rerouted or fitted with an accessible shutoff before the wall is closed again?
- Will my homeowners policy treat this as sudden water damage, and does the cause of the crack affect that?
Common questions
Who do I call first, the irrigation company or a restorer?
Close the inside irrigation valve so the water stops. The irrigation or plumbing repair can follow, but if a finished wall or carpet is wet, get moisture readings promptly so the cavity is dried before it starts to smell.
General information for Parker, not a quote or professional advice. In an emergency, call 911.