A pressure-vacuum breaker is an important part of any irrigation system. It’s required by most cities because it prevents contamination of the potable water supply. It works by breaking back-suction on the lines should water pressure fall, thereby preventing contamination from being drawn back into the water supply. You can call the local building code office to find out if it is required, but even if it is not required in your area, it is a good idea to install one. Installing a vacuum breaker yourself can save you money on the cost of installation.
Pressure-vacuum breaker installation can be easy, especially if you have a PVC main water line. Usually, you want the pressure-vacuum breaker fitting to be located close to the sprinkler valves and right after a stop-and-waste valve, especially if you live in a colder climate. This vacuum-breaker installation configuration will help drain the line when you shut down the irrigation system for the winter.
Before You Begin
Turn off the water. Carefully dig up the area between the valves and the main sprinkler shut-off. To install a pressure-vacuum breaker, you should need only about 12 to 18 inches of space.
If you do not have a shut-off valve here, it might be a good idea to install one now.
Source: The Spruce