If you live in an area where it never freezes, you can skip this section. But even if it only freezes in the morning, you need to protect your irrigation system to some degree.
Winterizing your irrigation system consists of these steps:
- Turn off the water to the irrigation system at the main irrigation shut-off valve.
Most irrigation systems have a single valve that can be used to disconnect the entire sprinkler system from the water system. This is important if you need to repair a sprinkler valve and want to leave the water on in the house. Liken this main valve to the one under your sink that turns the water off (at that location) so that the faucet can be repaired without turning off the water to the rest of the house.
- If the main irrigation shut-off valve isn't in a heated room, use pipe insulation to insulate it, or use heat tape to prevent freezing.
- Turn on each of the sprinkler valves for a few moments to release pressure in the pipes.
- Set the automatic irrigation controller to the rain/off setting.
- Drain all of the water out of any irrigation components that might freeze.
In temperate climates, underground valves and sprinklers are generally safe. But if the temperature remains below freezing for days at a time, these components can be severely damaged if the water isn't drained out of them.
Landscape irrigation maintenance companies use compressed air to remove the water from a sprinkler system. A special air compressor is used. They're special because they produce a different pressure and volume than the type of compressors most of us are used to seeing in the home and shop. Too much pressure can destroy the valves, pipes, and sprinklers. You may want to hire a professional for this job.
If you have a backflow prevention device that is exposed to the weather, it must be drained and protected from freezing. Once drained, wrap it with two or three layers of foam insulation. Some agencies recommend removing it altogether and storing it in a heated area during the winter.