How to Install a New Backflow Preventer for a Sprinkler System

A water sprinkler is a necessity during the summer heat for many gardens and lawns. A backflow preventer installation is easy if you are familiar with the water lines in your home, know what a backflow preventer is, and follow these simple steps.

By law, you are required to have a backflow preventer in your home that prevents dirty or contaminated water from entering the public water supply. Your backflow preventer is attached to the main water supply line of your home. If your backflow preventer is not functioning, you will first need to replace it before installing your new sprinkler system. (By town mandates and the DEP, this will need to be done regardless of whether you need a sprinkler.)


  • For replacement of the backflow preventer, first switch off the water supply to the main line and open the valves of the backflow preventer to drain any excess liquids.
  • Loosen the bolts on either side of the backflow preventer and the air-gap catch basin screw to remove the device from its position.
  • In the same manner, you will install your new backflow preventer, ensuring that its position follows in place with the water flow indicators.

Your sprinkler system is now ready to be attached to your home’s main water supply line and the new backflow preventer. Screw the hose in place and your lawn and garden will look once again, new and fresh, at just a fraction of the cost. Just don’t forget to turn the water supply line back on!