If freezing temperatures are forecasted, and your irrigation system has not yet been winterized, you will need to drain the backflow prevention device to prevent freeze damage to your system.
IMPORTANT: Draining your backflow is not a substitute for a complete blowout and winterization.
Step 1) Locate the main irrigation water shutoff. If inside the house, it is often located near the water meter and/or main water supply line, or in the basement ceiling.
Step 2) Shut off the water.
Step 3) Go outside the house and locate the backflow preventer. Turn all valves to 45 degrees.
Step 4) Most devices will have between one and four Test Cocks. Turn all Text Cocks to 45 degrees.
5) Open all drains. There are a variety of drain types. Have a bucket ready, as water may drain out! If there is no indoor drain, it is critical to open the outdoor drain.
6) If the system has any above ground hose bibs, open them.
7) Turn the clock off.
IMPORTANT: You still need to have your system blownout and winterized. Draining your backflow preventer will protect it from early freeze damage, but will not protect it from freeze damage when the ground freezes in winter.