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How to Winterize Your Sprinkler System

Maintain your sprinkler system through the winter and your lawn will look its best next season.


  • TIP: While you can blow out an AVB backflow system, you should never force compressed air through PVB or RP systems. They contain rubber seals that can melt from the heat of the air.
  • Step 1: Make sure the isolation ball cock on the downstream side of the backflow device is closed, connect the air compressor to the downstream blowout fitting, start your zones at the controller, and turn the compressor to the pressure indicated in your owner's manual. Once all of the zones are blown out, return the cock to the halfway position.
  • Step 2: Blow out each zone two times to make sure all of the water is out of the system. Remember to take your time and properly winterize your system to ensure that it works properly and to avoid costly repairs.
  • FACT: Cool season grasses, such as Kentucky bluegrass, require as much as one to one-and-a-half inches of water per week to maintain color and growth.
  • Step 3: Drain your Reduced Pressure, or RP, backflow device if your system is equipped with one. Close the main shutoff valve and open the stop and waste valve. Open the cocks in the first check zone to drain the water between the first and second check valves. Then go to the downstream air port and remove the check cap to drain the water downstream of the second check. Replace the cap and leave the ball valves open for the winter.
  • Step 4: Drain a Pressure Vacuum Breaker, or PVB, if your system has one, by opening the interior supply drain and the exterior upstream drain. Make sure the ball valves are open, open both test cocks, and then remove the cap from the downstream air port to let the water drain out. Replace the cap and leave the test cocks in the half-open position for the winter.
  • TIP: Do not force the valve when opening or closing it. Like any faucet valve, you risk breaking it if you force it.
  • Step 5: Drain your system's pump if it has one. After the pump is drained, either detach it from the system and store it inside or cover it with bubble wrap or Styrofoam to insulate it. This reduces the risk of residual moisture freezing or cracking the pump.
  • Step 6: Winterize your Atmospheric Vacuum Breaker, or AVB, if your system has one. An AVB backflow device can be blown out using an air compressor.
  • Step 7: Turn off the water supply to your system at the stop and waste valve. The stop and waste valve may be located in your crawlspace or basement, or in an underground valve box which requires a long key to turn.

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