HOW TO: Winterize Your Irrigation System

It's time to winterize your irrigation system. And it's not one of those tasks you want to put off, because before you know it, it'll be too late. Winterizing is one of those thankless preventative tasks that, if done correctly, you won't even fully appreciate until next spring when you're not out there digging up water lines looking for those long spiraling, lengthwise cracks that reveal a classic freeze break.

Winterizing your irrigation system also can be one of the most cost-preventative things you can do for your business. However, winterizing procedures take time and must be completed before the first freeze occurs.

  1. Shut off the water completely, making sure that no water is entering the system. The main shut-off valve for your irrigation system needs to be “freeze proof.” If the main waterline breaks and allows water to get back into your system, you do not gain anything from the following steps.

  2. Shut off automatic systems. Some irrigation systems offer a setting for shutting off the water flow while keeping the system up and running, but you're better off shutting the system completely off. This also saves electricity. But you'll need to plan on reprogramming the system in the spring. It also is a good idea to completely remove controllers from power supplies and store them, taking all steps necessary to protect the wiring. The greater the potential for periodic severe freezes, the more sense it makes to deactivate the system.

  3. Analyze the system to find all possible locations for water entrapment in an exposed pipe or piece of equipment, and then take the necessary steps to thoroughly drain them.

  4. Drain irrigation components that hold water. Open any component that allows water flow to make sure that no water is stored above the shut off. During the draining process, check sprinklers located in low spots where surface water could accumulate and drain back into the system. Do not overlook any openings where water could reenter the system.

  5. Drain the water from the pipes. You can do this using gravity or by blowing out the pipes. Blowing out the pipes is more thorough and will ensure that you're getting the water out. The key to blowing out your irrigation system successfully lies not in high pressure but large volumes of air. You have to have enough air to push all of the water out of the system. With enough air, you only need to have about 50 psi to blow out most systems. It is a good idea to run air through your system twice with each winterization project.

  6. Insulate components and valves above ground. You can use insulation tape for this. Do not block the air vents and drain outlets on your systems components.

Sources: Dirk Lenie, “Weathering the Winter,” Grounds Maintenance, October 1999; Jess Stryker's Landscape Irrigation Tutorials,; RainBird,

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