How to Install a Sprinkler Backflow


A home irrigation system is designed to lessen the burden of watering the grass and garden. When these systems are designed, several factors are taken into account. Some of these factors are water supply, overall needs, ease of use and local requirements. Some municipalities require a home irrigation system to have a separate water supply source. This is done by adding a second supply to the house for homes with municipal water supply or drilling a new well for homes on a well system. For areas that allow the house to supply the system, most require some type of separation between the house drinking supply and the irrigation system. A small backflow preventer creates this division and can be installed by the average homeowner with a basic knowledge of plumbing.

Step 1

Locate the supply line for the irrigation system. Most supply pipes are located in the basement of the home if the system is supplied by the home water system. Well-supplied systems have the supply pipe right off the pump.

Step 2

Turn off the water to the irrigation system. If the system is supplied by the home system, the shutoff valve will be on the supply line to the irrigation system. For well-supplied systems, turn the pump power off.

Step 3

Turn the irrigation system on. This will drain the water pressure from the system.

Step 4

Wrap the Teflon tape around the threads on the threaded fittings. This will create a tight seal on the threads and prevent leaks.

Step 5

Install the threaded fittings in both ends of the backflow prevention valve. Do not overtighten the fittings; they should be no more than hand-tight.

Step 6

Hold the valve next to the supply pipe and mark both ends on the supply pipe. The marks should be at the ends of the threaded fittings, not the valve.

Step 7

Cut the supply pipe on one of the marks, and then cut the pipe 1/2 inside of the other mark. Inside means closer to the other mark or cut. This will give enough room to install the valve properly.

Step 8

Install the valve in the supply line according to the requirements for the type of pipe. PVC pipe will require glue, where flex pipe will require crimp fittings. Check with a local home improvement professional or plumber for proper connection requirements for the type of pipe used.

Step 9

Turn the water supply back on and check for leaks.

Step 10

Turn off the irrigation system.

Tips and Warnings

  • Backflow valves are one-way valves; make sure it is properly oriented. Make sure the arrow on the valve is pointing in the proper direction.

Things You'll Need

  • Saw
  • Threaded fittings
  • Teflon tape
  • Backflow prevention valve
  • Marker


  • Grounds Maintenance Magazine: Irrigation Back Flow Prevention; August 2009
Keywords: irrigation backflow, backflow prevention, anti backflow