How to Replace an Irrigation System's Pressure-Vacuum Breaker

A pressure vacuum breaker (PVB) is a standard fitting on irrigation systems, as well as in many other applications. The device is designed to sense backward suction (a pressure vacuum) in the lines and then introduce air into the system to prevent contaminated water from being drawn back into the fresh water supply. Because it's an important component of an irrigation system, you must make sure it is operating correctly.

Replacing a pressure vacuum breaker may become necessary when the brass components break or when it needs a repair and you can’t find replacement parts. Changing a pressure vacuum breaker usually consists of cutting some PVC pipe, removing the old breaker, and installing a new one. A pressure vacuum breaker is meant to be installed at a height of at least 12 inches above the highest sprinkler head or outlet. Keep this height in mind when making repairs.​

If you happen to have union couplings that join the PVB to the irrigation lines, then it will make replacing the breaker much easier. If not, it is a good idea to install the union fittings while replacing the breaker. If you live in a cold climate where freezing is normal in the winter, then you know the toll that winters can take on a pressure vacuum breaker. Removing your PVB in the winter and storing it somewhere warm is often the best plan for protecting it from freezing. An alternative is to have the vacuum breaker drained down when the sprinkler system is winterized, then insulating the breaker. Here is how to replace a pressure-vacuum breaker in a PVC irrigation system.

Before You Begin

Look at the old pressure vacuum breaker and see how it is laid out before you go to the store. See how much pipe you have to play with and determine if you have room for unions if you plan to add them. Most importantly, determine the size of the pressure vacuum breaker (this should be printed on the side) and the size of the pipe (the sizes don't always match). If you are confused about any parts, take a picture with your phone or camera and bring it into the home improvement store or irrigation store for reference. If necessary, buy whatever male adapters, 90-degree elbows, unions, couplings, pipe, plumber's tape, glue, and primer are necessary.