Houston Why "Winterizing" Means Something Different Here
If you moved to Houston from somewhere with real winters, you probably remember a service called a blow-out: a tech hooks compressed air to the irrigation system every fall, pushes the water out of the pipe, and leaves it empty until spring. That service exists because in cold climates, water sitting in buried pipe can freeze solid, expand, and split the line before anyone notices. It's a smart, necessary fix for that specific problem — and it's not a problem Houston's buried irrigation pipe actually has.
What Actually Happens to Buried Pipe Here During a Hard Freeze
Houston gets hard freezes. February 2021, December 2022, January 2024, January 2025 — the metro has had enough multi-day cold events in a few years that this isn't a hypothetical. But even in the worst of those stretches, the ground a few inches down at typical irrigation pipe depth never gets close to freezing on the upper Gulf Coast. Soil is a slow, forgiving insulator, and our cold snaps simply don't last long enough or run deep enough to pull buried laterals, mainline, or in-ground valves down to 32°F. That's exactly what the 2021 event confirmed: the catastrophic plumbing failures that winter were almost all in attics and exterior walls — homes here don't have basements, so exposed pipe ends up overhead instead — and in outdoor assemblies sitting above grade. Buried sprinkler pipe came through that storm overwhelmingly intact.
There's also a practical reason nobody blows out a Houston system even for the homeowner who insists on it: most local systems were never built with a blow-out port. Improvising a compressed-air connection onto a system that wasn't designed for it isn't a routine service call, it's a modification, and it comes with real risk. Air pushed through at the pressures needed to clear a line can blow out valve diaphragms and chew up rotor gears that were never engineered for it. You'd be introducing a failure mode to solve a problem the ground here doesn't have.
The One Part of the System a Freeze Actually Reaches
Every water-carrying part of a Houston irrigation system is buried except one: the backflow prevention assembly, which has to stand above ground and above the highest sprinkler head to do its job at all. That makes it the only component cold air can reach directly, and it's genuinely vulnerable — water expands roughly a tenth of its volume as it freezes, and that's enough to split a casting, classically through the domed bonnet of a pressure vacuum breaker. This is the one piece of freeze prep worth doing every single year before a hard freeze arrives, and it's four steps:
- Close the irrigation isolation valve feeding the assembly.
- Open both test cocks and part-open the shutoff handles so the assembly actually drains — don't skip this; insulating a full assembly just protects the water that's about to crack it.
- Wrap the drained assembly with insulation (foam cover, towels, whatever's on hand — it's maybe $15 in materials against a mid-hundreds-dollar replacement).
- Make sure the controller isn't scheduled to run a zone onto a freezing driveway or sidewalk overnight.
If a backflow assembly does crack, it usually doesn't announce itself until the first warm-up. Walk it before any zone runs, and read more on diagnosing a cracked or leaking unit on the backflow preventer repair page.
Coming Back Online the Right Way
After a freeze, the sequence matters as much as the freeze prep did. Open the isolation valve slowly — a mainline that's been sitting empty refills through dry pipe at surprising velocity, and snapping the valve open fast can crack fittings the cold itself never touched. Then run each zone individually and watch it; a hairline crack in a riser or a seal damaged by ice inside an otherwise intact valve body often only shows up once pressure is back. A broken lateral or riser found in March is an ordinary scheduled repair; the same damage found in late May is competing with every other service call in the metro. If you find a break in the buried line itself, that's covered on the buried pipe repair page, and a full once-over before the growing season starts is exactly what a spring system audit is for.
The Takeaway
Houston's climate never freezes buried irrigation pipe, so blow-outs solve a problem this area doesn't have — the only freeze prep worth doing here is draining, insulating, and timing around the one assembly that sits above ground.