Irrigation Winterization (Blow Out)

By: Franz Witte

What is irrigation winterization?
Irrigation winterization (often called a “blow out”) is the process of making an irrigation system safe from freeze damage over the winter. This is accomplished by removing most of the water from the irrigation pipes, valves, sprinkler heads, and other components of the system. Compressed air is used to push the water out of the system: a compressor is connected to the irrigation mainline and then the valves are operated, allowing the air to push the water through the mainline to the valves and lateral lines and out of the heads.

Why is it important to winterize an irrigation system?
Freeze damage to irrigation system components can be very destructive and expensive to repair. It can destroy dozens of feet of PVC or poly pipe, crack solenoid valves, and even split metal pipes.

​Here’s how it happens: When air temperatures drop below freezing for extended periods of time, the ground begins to freeze from the surface downward. The longer and colder the freeze, the deeper into the ground the frost line will reach. If the frost line reaches irrigation components that are full of water, the water will freeze and expand pushing outward on the component surrounding it. This can cause the component to crack or shatter.
However, if most of the water has been blown out of the system, any remaining water will simply freeze and expand into the air inside the pipe or valve.

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