Question: Do I have to worry about my sprinkler system freezing in the winter?
Answer: Not if it was installed properly. The only lines that will freeze are those that are under pressure constantly, that is, the supply lines to the valves. The risers and other heads and the lines that supply them directly won’t freeze, since the most of the water should drain out of them after they shut off. Do be careful, however, that your system doesn’t come on during freezing weather. Not only can it cause an ice hazard on paved surfaces, but it can also weight down your plants to the point of breaking. Freeze guards and “smart” controllers both prevent that happening.