Your sprinklers worked hard all summer. Now they need one last job done before they clock out for the year: getting every drop of water out of the lines. 

It’s easy to forget about. The system is buried, the lawn is going dormant, and nobody’s thinking about irrigation when they’re raking leaves and prepping their lawn. But one cold snap with water still sitting in those pipes can leave you with a spring repair bill that’s a lot bigger than a fall winterization. 

What a Freeze Does to an Irrigation System 

Water expands when it freezes. Inside a sprinkler line, it has nowhere to go, so it pushes outward until something gives. That something is usually: 

  • Pipes and fittings that split underground, where you won’t see the damage until spring 
  • Sprinkler heads that crack and spray sideways (or not at all) 
  • Valves that stop opening and closing on schedule 
  • The backflow preventer, which sits above ground and takes the brunt of the cold 

And the worst part? You won’t know until spring activation. That’s when soggy patches, water spraying from broken heads, and dead zones show up. And you were expecting your lawn to green up. 

How We Winterize Your System 

Our irrigation technicians follow the same process at every property: 

  • Shut off the backflow so no new water enters the system.
  • Blow out every line with compressed air, zone by zone, clearing water from the pipes, valves, and heads. 
  • Tag the backflow so you (and anyone else on the property) know the system is winterized and shouldn’t be turned back on until spring. 

A garden hose and some draining won’t get it done. Compressed air is what pushes water out of the low spots and long runs where it likes to hide. 

Already on our preventive maintenance program? Your winterization is already included. The program also covers spring activation, the annual backflow test St. Louis County requires, and three system checks during the season. 

Why a Blowout Isn’t a DIY Weekend Project 

Plenty of homeowners have a compressor in the garage, and it’s tempting to handle the blowout yourself. Here’s why it’s worth leaving to an irrigation pro: 

  • Too much pressure does damage. Heads, fittings, and valves are built for water pressure, not whatever your compressor can crank out. Overdo it and you can crack the very parts you’re trying to protect. 
  • Running air through a dry line overheats it. Once the water’s out, air moving through the plastic pipe creates friction and heat. Technicians at Horstmann Brothers know when a zone is clear and it’s time to move on. 
  • The backflow is the most expensive part to replace. It’s also the easiest to mishandle. Getting the shutoff sequence wrong can leave water trapped exactly where you don’t want it. 
  • Missed zones are common. Larger properties often have zones that are easy to forget, especially drip lines feeding garden beds and containers. 

A professional winterization takes the guesswork out of it. Our technicians work zone by zone until every line runs clear, then tag the system so there’s no question it’s done. 

Sprinkler Winterization FAQs 

It’s still warm out. Isn’t it too early? Not at all. Once the lawn slows down for the season, it doesn’t need regular watering, and late fall rain usually picks up the slack. Winterizing a little early costs you nothing. Winterizing a little late can cost you a broken system. 

What if we get a mild winter? Even mild St. Louis winters bring nights well below freezing, and it only takes one to crack a fitting. There’s no way to know ahead of time which week that will be. And knowing St. Louis, there is no such thing as a mild winter. We wish that were the case!  

I’m not sure my system was winterized last year. How can I tell? Watch for warning signs during spring activation: wet spots that never dry out, heads that won’t pop up, low pressure in one zone, or water bubbling up from the ground. If any of that sounds familiar, mention it when you schedule. We’ll take a closer look while we’re there. 

When does the system get turned back on? In the spring. Our technicians handle the activation, run an efficiency check on every zone, and can complete your annual backflow test during the same visit. 

Mark Your Calendar: Third Week of November 

We recommend having your system winterized no later than the third week of November! St. Louis weather loves a surprise, and an early hard freeze doesn’t wait for your schedule to open up. 

The sooner you get on our list, the easier it is to land a time that works for you. And if your system had issues this summer, like a broken head, a zone that never quite kept up, or a controller that’s seen better days, let us know when you call. We can flag it now and have a plan ready for spring. 

Call Horstmann Brothers at (314) 432-0880 or request an appointment online to schedule your sprinkler winterization. We provide seasonal maintenance to personally care for your property throughout all of the seasons.