How to Install a Backflow Preventer for a Sprinkler System

The pressure vacuum breaker is a key piece of safety equipment that is required on most sprinkler systems. These devices keep the water inside your irrigation lines from flowing back into the main water supply lines. This is important because water that enters sprinkler pipes is exposed to chemicals, such as PVC glue, and should not be used as potable water. Installing a vacuum breaker is a relatively straightforward process that can be accomplished with just a wrench and some pipe sealant.

Pressure vacuum breaker
Teflon tape
Wrench

Instructions

- 1
  Run the sprinkler supply pipe to the area of the sprinkler manifold.
- 2
  Apply a layer of PVC cement to the inside of a 90-degree elbow adapter and press the adapter onto the end of the sprinkler line so that the adapter is pointed straight up.
- 3
  Screw a 2-foot riser into the elbow adapter.
- 4
  Cut the riser off using a hack saw at the point 12 inches above the highest sprinkler on the system. The breaker must be installed at least 12 inches higher than the highest valve. In most cases, installing the breaker at least 15 inches above the ground is more than adequate.
- 5
  Coat the inside of a PVC male adapter with PVC cement and press the adapter onto the top of the cut-off riser.
- 6
  Screw the outlet of the vacuum breaker onto the male adapter. Turn the breaker until tight, but stop when the connection becomes difficult to move by hand.
- 7
  Insert a male PVC adapter into the inlet of the vacuum breaker, turning it clockwise until tight.
- 8
  Apply a layer of PVC cement to the inside of a 90-degree elbow adapter, and press the adapter onto the end of the inlet adapter so that the opening on the elbow points down.
- 9
  Connect the sprinkler manifold's outlet pipe to the elbow adapter. Depending on your model of manifold, you may need to glue the pipes together or screw them together and tighten the connection with a wrench.
- 10
  Turn both of the ball valves on the vacuum breaker so that the handles are at 90-degree angles to the valves.

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