Step 1: Turn Off Main Valve
Locate your irrigation main valve. This is often close to the backflow prevention device. There are typically two kinds of main valves; the first looks like a spigot handle which is a gate valve. The second looks like a t-handle called a ball valve (shown in picture).
Expert Tip: If you turn this off and get complaints from the household that there is no running water, one of two things could have happened. (1) You either turned off the main water or (2) someone mistakenly connected irrigation lines to the main water line. If it is the latter you need to contact an irrigation specialist.
Step 2: Turn Off Backflow Device
Turn the handle attached to your backflow preventer, perpendicular to the device. This is typically the off position.
Step 3: Open Outlet Drain
Connected to your backflow device, there will be an outlet side drain. This is the one to open.
Step 4 (Optional): Open & Close Valves
This step is optional if you plan on using compressed air to remove all remaining water in your system (highly recommended). Systematically run through the system, opening and closing each valve. This can be done manually from each sprinkler head or from your clock. Doing this relieves excessive water pressure from the system, protecting lines and heads during the compressed air step.
The video shows how to open and close an irrigation valve.
Step 5: Blow Out Water
Hook up a high volume-low pressure air compressor to your backflow prevention device test port. Turn on the air compressor to charge main-line, this will expel all remaining water.
Step 6: Open Valves
Slowly open valves one at a time to blow remaining water out of the opened zone. After all water is expelled from the valve, proceed to the the next and repeat process until all zones have been worked through.
Step 7: Open Drains
Leave all drains to the open position. All drains should remain this way until you start up your system the following spring.
Expert Tip: Remember to close drains when you start your system up in spring, otherwise all the water will be flowing wildly through your system.