With winter just around the corner, it's time to winterize irrigation systems.

In our area, the most common practice is to use compressed air to blow out residual water in the irrigation piping. When performed correctly, this can be an efficient method to prevent expensive damage to irrigation systems caused by freezing. If performed incorrectly, however, costly damage to backflow assemblies can occur. It can also result in contaminating your water, as well as your neighbors' water.

The following guidelines will help provide protection from contamination.

1. Make sure that the blow-off port where air is introduced to the irrigation system is downstream of your backflow assembly. Blow-off ports installed upstream of the backflow assembly can allow oil and contaminated air from the air compressor tank to be back-pressured into your potable water service as well as the city water main. High pressure air introduced upstream of the backflow assembly can also damage the internal parts of the assembly, resulting in the assembly not properly protecting our drinking water supply. It may also require costly repair/replacement of the assembly.

2. If your irrigation system is protected by a pressure or atmospheric vacuum breaker, it must be removed before the introduction of compressed air because these assemblies can be damaged if subjected to air from either upstream or downstream.

3. City code requires the backflow assembly to be installed with unions so it can be removed before the introduction of compressed air, and stored inside for the winter. If the assembly was installed without unions and cannot be removed to prevent freezing, then it must be thoroughly drained.

4. Perform your required annual backflow assembly test at spring start-up no later than July 1 to make sure the assembly is operating correctly.

For more information, contact the city's water department at 769-2220.