During the winter, your lawn and garden may not need the sprinkler system, so it makes sense to turn it off. When the time comes in the spring, however, you'll need to turn it back on. With the sprinkler system working, your grass and flowers can get the water that they need to grow bright and lush.
The most important thing to remember when turning on a sprinkler system is to turn on the water slowly. You can create a huge water hammer—a shock wave caused by a sudden change in water flow—by turning the water on too quickly. This can burst fittings or pop off sprinkler heads. Always open the system shutoff valve slowly to let the system pressurize gradually; it takes just a few seconds.
Equipment / Tools
- Flat-head screwdriver
- Sprinkler valve key (as needed)
- Note pad and pencil
- Pliers (as needed)
Locate the Main Shutoff Valve
If you don't know where your system's shutoff valve is located, look in your basement or crawl space for piping coming in near ground level. The piping should include a single shutoff valve, usually a ball valve with a lever-type handle. If there is a large water pipe coming in well below ground level, usually through a foundation wall, this is most likely your home's main water supply, not the valve for the sprinkler system.
If there is no sprinkler system shutoff inside the home, look inside the sprinkler system valve boxes around the yard. The shutoff valve has a cross-shaped handle and may be well below ground level or inside a pipe.
Locate the Vacuum Breaker
Look for the vacuum breaker outdoors, above ground, usually near the house. This is a copper or plastic valve assembly connected to two pipes, each with a small shutoff valve.
Identify the Vacuum Breaker's Test Cocks
In addition to the shutoff valves, the vacuum breaker has two test valves called test cocks that look like slotted screw heads. They should be turned about 45 degrees to the direction of the nipples to which they are attached. This allows air into the valve to prevent damage from freezing during winter.
Close the Vacuum Breaker's Test Cocks
Close each of the two test cocks by turning it with a flat-head screwdriver so the slot on the test cock is perpendicular to the nipple.
Ball valves—whether they have screw-type controls, lever-type handles, or butterfly handles—are open when the handle or control slot is parallel with the pipe. They are fully closed when the handle is perpendicular to the pipe.
Open the Shutoff Valves
Next, open the two shutoff valves on the vacuum breaker. Each valve is located on a pipe leading to the valve and usually has a butterfly-type handle. Like the test cocks, the valve handles should be set at 45 degrees to the pipe for winterization. Open each valve all the way by turning the handle until it is parallel with the pipe.
Reinstall the Main Valve Bleeder Cap
Some system shutoff valves have a little metal cap that threads onto a bleeder nipple on the side of the valve. This is used to drain residual water from the piping during the system shutdown. If your shutoff valve has a bleeder nipple, make sure the cap is in place and is tightened snugly.
Open the Main Valve
Slowly open the main shutoff valve to let water into the sprinkler system. For a ball valve, turn the lever handle one-quarter turn until the handle is parallel to the pipe; this is the fully open position. For an in-ground shutoff valve, use a sprinkler valve key to turn the valve counterclockwise until it stops.
Run a Manual Test
Set the system timer to run a manual test of all of the sprinkler zones, running each zone for about 3 to 5 minutes. As each zone turns on, watch the sprinkler heads to make sure they are working properly, and write down any problems on a note pad, so you can come back to address later. The sprinklers will sputter and blow out air when they first come on; this is normal and will stop within a minute or so.
Check the Valves and Vacuum Breaker
Open each valve box in the ground and make sure there are no leaking valves or other problems. Confirm that all looks well with the vacuum breaker and the related valves and piping. Check the bleeder on the main shutoff valve (as applicable). If there is leaking from the cap, tighten it gently with pliers.
Get Ready to Irrigate
Correct any problems you noted during the manual test, such as adjusting spray patterns or replacing damaged sprinkler heads. Set the system timer for the first watering. If possible, it’s a good idea to water when you can keep an eye on the watering for the first time during the season to make sure everything is working properly. Afterward, it usually is most water-efficient to water at night or very early in the morning.