How Do I “Winterize” My Irrigation System Insulate your assets: Shut off the water supply to the irrigation system. Stay in control: If you have an automatic system then you will need to “shut down” the controller (timer). Drain the pipes: Protect valves and backflow preventers: Click to see full answer. In this way, what PSI Do I need to winterize my sprinkler system?Set the compressor air pressure regulator to a maximum of 80 psi for rigid PVC pipe systems, or 50 psi for flexible black polyethylene pipe. Then turn off the water supply and set the system timer to open just one zone. Next, open the manual drain valve at the end of that zone (if equipped).Also, when should I turn off my sprinkler system for winter? As the leaves begin to fall and temperatures start to drop, it’s time to shut down your lawn irrigation systems and prepare for winter’s bitter cold. Sprinkler pipes and other components are at risk of freezing and breaking when temperatures drop below 32 degrees Fahrenheit. Beside above, how do I winterize my sprinkler system without an air compressor? You can winterize a sprinkler system without an air compressor if all of your irrigation lines are buried at a slight downhill slope. Simply shut off the main water supply to your system and open the drain valves at the end of each zone.How much does it cost to winterize your sprinkler system? Sprinkler System Winterization Average Costs Hiring a professional to winterize a sprinkler system typically costs $50 to $150 depending on the system size and local rates. Air compressor rental runs approximately $30 to $60 per day. A half-day rental, which should be sufficiently long for the job, is slightly cheaper.