San Antonio doesn't get the hard freezes that northern states deal with every winter. But the occasional freeze event like the one in February 2021 can destroy an unprotected irrigation system in a single night.
On average, San Antonio sees 10–15 nights per year below freezing, mostly in December through February. Most of these are mild dips into the high 20s that last a few hours. Standard PVC irrigation systems can handle brief, shallow freezes if they're properly drained.
The risk comes from extended hard freezes when temperatures stay below 25°F for 12+ hours. The 2021 winter storm held San Antonio below freezing for over four consecutive days. Backflow preventers, above-ground pipes, and any standing water in the system froze and expanded, cracking housings, splitting pipes, and destroying valves.
Learning how to winterize sprinkler system San Antonio setups properly is essential for preventing costly emergency repairs when cold fronts roll through. Full blowouts (using compressed air to force water out of every line) are standard practice in cold climates but usually overkill for San Antonio. What you should do: insulate your backflow preventer and any above-ground piping with foam insulation covers. These are cheap ($10–20) and prevent the most common freeze damage.
Disconnect and drain any hoses connected to the irrigation system. Shut off the system when freezing weather is forecast running a frozen system pushes water into cracked components and makes the damage worse. Taking these proactive steps before temperatures drop ensures your pipes remain intact and prevents sudden water pressure loss during unexpected freezes.
After any freeze below 28°F, walk the system before turning it back on. Check the backflow preventer for visible cracks. Look for wet spots in the yard that weren't there before. Run each zone individually and watch for new leaks, geysers, or zones with drastically reduced pressure.
After the 2021 freeze, we repaired hundreds of systems across San Antonio. The most common damage was cracked backflow preventers ($200–400 to replace), split PVC at joints and elbows, and broken valve internals. Homeowners who had insulated their backflow and drained their systems before the storm had dramatically less damage.
Moore Irrigation offers pre-winter checkups in November and December. We insulate exposed components, verify drainage, and check for existing issues that could become major problems during a freeze. Taking the time to winterize sprinkler system San Antonio properties now will save you hundreds of dollars in repair bills come spring.
