How to Winterize Sprinklers: A Hands-On Guide for Small Business Owners

If you run a small landscaping business, property maintenance firm, or just manage your own site’s irrigation, freezing temperatures can be your system’s worst enemy. We've walked in your shoes—sold components, serviced systems, jumped on emergency calls—and we want to make your winter prep as safe and stress-free as possible. In this guide, you’ll learn how and when to winterize sprinklers, how to drain sprinkler systems and prevent sprinklers from freezing, and how to use a good sprinkler blowout kit for your own business site.

Cold weather and leftover water don’t mix. As temperatures dip, any trapped moisture in your system can freeze and expand, cracking lines or damaging valves. For business owners, that can mean downtime, unexpected repair costs, or damage to sidewalks, landscaping, or adjacent equipment. That’s why sprinkler freeze damage prevention is less about the season and more about strategy.

If you're wondering when to winterize sprinklers, aim for early action. Most systems should be winterized when nightly lows drop below 40°F, well before the first frost. It gives you time to shut things down without racing the weather and helps avoid emergency calls later. If your facility is in a colder region or has consistent exposure to the elements, plan your prep in early fall.

For businesses, winterizing underground sprinkler systems often comes down to scale and safety. Automatic drain systems can help in some setups, but manual prep is still common, especially in larger or older systems. Many operations use the irrigation line blow-out method. This involves pushing compressed air through the lines to clear residual water. It’s fast and effective when done correctly. Using the wrong pressure or equipment can damage your system. If you have an in-house maintenance crew, they may already have a procedure in place. Otherwise, hiring a licensed contractor ensures the job gets done safely.

Getting your sprinkler system ready for cold weather doesn’t require a full toolbox, just a few essential items. An air compressor can help clear out leftover water using the blow-out method. An insulated blanket or cover adds a layer of protection over backflow preventers and other exposed parts. Depending on your setup, a sprinkler system winterization kit might be useful; these typically include connectors and adapters designed to work with a range of irrigation systems.

Most commercial sprinkler systems can be winterized with a consistent approach, no matter the brand or layout. Here’s a general walkthrough.

• Step 1: Shut off the water supply.  Locate your main shut-off valve (usually indoors in a mechanical room, basement, or utility space) and close it to stop water flow to the system.

• Step 2: Drain any remaining water.  Open manual drain valves zone by zone to release trapped water.

• Step 3: Use the blow-out method.  Attach an air compressor to the system’s mainline and work through each zone individually. Open each valve briefly to allow compressed air to clear the pipes.

• Step 4: Insulate exposed components.  Once the system is drained, cover any above-ground parts like backflow preventers or valve boxes with insulating materials to reduce the risk of freeze damage.

Some commercial-grade irrigation setups include automatic sprinkler winterization features: valves or drains that discharge water without manual input. If your system includes one, it's worth inspecting ahead of winter to ensure everything’s in working order. These systems aren’t maintenance-free, but they do add a layer of protection with minimal oversight.

The backflow preventer keeps your sprinkler water from contaminating your main water supply. During backflow preventer winterization, make sure to drain and insulate this device properly. It’s especially vulnerable to cold and can be expensive to replace. Skipping this step could compromise water safety or require costly rework down the line.

Winter prep doesn’t have to be complicated. Whether you’re using compressed air, checking backflow valves, or inspecting your controllers, your goal is the same: keep your system intact through the freeze. Zoro carries the supplies that make winterizing smoother: hoses, air compressors, fittings, covers, and more. 

Product Compliance and Suitability

The statements contained in this guide are intended for general informational purposes only. Such statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness, or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand, and follow all manufacturer instructions. Portions of this article were generated in part by ChatGPT, and edited by a member of the Zoro team.