Proper upkeep of underground sprinkler systems almost guarantees proper function for the following seasons. Water Smart Montana, LLC annually winterizes systems the first week in October. Systems are drained where accessible and water lines are blown out with an air compressor. Backflow preventers are left in proper positions. System startups rely on the weather, but generally begin the first week in May. Systems are re-charged and tested to be at working standard. Backflow preventers are inspected while valves are active and when they are not. Valves are made sure to seal and sprinkler heads are adjusted or replaced when needed.