Backflow devices are intended to keep water from your irrigation system from being drawn back into your home’s water supply. There are several different types of these devices, some of which are pictured here. They are often mistakenly identified as a pump or valve. Many times, these devices are the only part of an irrigation system that is above ground and therefore, the first casualty of freezing temperatures. Unfortunately, they also may be one of the most expensive single parts of your system. Be sure these devices are covered or drained as necessary during freezing conditions. Click on the link/pdf below for a diagram to help you make sure your Pressure Vacuum Breaker doesn't freeze. Many cities require regular testing of these devices, which Turf Solutions is licensed to perform on your behalf.
Document: Start-up and shutdown procedures for PVB