An automatic irrigation system is a convenience for maintaining a healthy landscape, but there are times when the water supply must be stopped. Homeowners need to know how to isolate the system for routine maintenance, emergency repairs like a burst pipe or a faulty valve, or the seasonal process of winterization. The procedure ensures a quick stop to any water flow, preventing waste and property damage. Properly shutting off the water involves a sequence of actions, starting with locating a specific valve and ending with draining residual water from the pipes.
Locating the Main Sprinkler Isolation Valve
The first step in controlling the system is finding the dedicated shut-off valve, which is distinct from the main house water valve. This isolation valve is specifically installed on the branch line that feeds only the sprinkler system, allowing the rest of the home to remain operational.
In properties with basements or utility rooms, the valve is often found indoors near where the main water line enters the structure. For many properties, the isolation valve is located outside, typically housed inside a green or black plastic box buried in the ground near the water meter.
This valve is frequently a ball valve, recognizable by its lever handle that runs parallel to the pipe when open and perpendicular to it when closed. Locating this specific valve is important because turning off the main house valve will stop all water flow, including to sinks and toilets.
Procedure for Turning Off the Water Supply
Once the isolation valve is identified, the next step is to physically operate it to halt the flow of water into the irrigation lines. The method of operation depends on the type of valve installed, which is usually either a ball valve or a gate valve. A ball valve is the most common type and requires only a quarter-turn, or 90-degree rotation, to move the handle from the open position to the closed position.
If the valve has a round, multi-turn handle, it is likely a gate valve, which requires several clockwise rotations until the handle stops turning completely. It is important to turn any valve gently to avoid damaging internal components.
After closing the valve, homeowners should briefly run a zone from the controller or open an outside spigot connected to the system to confirm that the water has stopped flowing. This verification step ensures the water supply is fully isolated before any maintenance or repair work begins.
Deactivating the Irrigation Controller
After the water supply is manually shut off, the electronic controller or timer must also be deactivated to prevent the system from attempting to run a scheduled cycle. The controller sends a low-voltage electrical signal to the solenoid on each zone valve to open it and start watering. If the water supply has been stopped but the controller is still running, the solenoids will activate and cycle without water, which is not ideal for the components.
Most controllers feature a simple switch or button to set the system to the “Off” position, or a “Rain Delay” mode, which pauses the programming without erasing it. For a long-term shut-off, such as for winterization, simply unplugging the controller or flipping the dedicated circuit breaker is effective. This electronic deactivation prevents the zone valves from opening and ensures no unintended cycling occurs while the system is depressurized.
Managing System Pressure and Backflow Devices
With the water supply and power successfully turned off, the remaining step is to relieve the residual pressure and drain the water trapped within the pipes. This is especially important for winterization, as trapped water expands when it freezes, which can crack pipes and damage the backflow preventer.
The backflow prevention device, often a Pressure Vacuum Breaker (PVB) or Double Check Valve Assembly (DCVA), is installed to protect the potable water supply from contamination. To relieve pressure, the test cocks on the backflow device, which are small brass fittings, should be opened using a flathead screwdriver. These ports allow the water between the shut-off valve and the backflow device to drain out.
The two main ball valves on the backflow preventer should also be turned to a 45-degree angle to create a path for water to escape. Systems with manual drain valves are often located at the lowest point of the irrigation lines. Opening these valves allows gravity to pull the remaining water from the system, protecting the integrity of the components from damage.