The transition from the dormant winter period to the active growing season requires the careful reactivation of the home irrigation system. This seasonal startup is necessary after the system has been drained and winterized to prevent damage from freezing temperatures. Homeowners must follow a methodical process to safely reintroduce water pressure and prevent damage to pipes and components. This guide outlines the steps for safely turning on the water supply to a residential sprinkler system.
Preparation and Locating the Main Shutoff Valve
Before introducing water, preparation is required to prevent flooding or system damage. Gather simple tools, such as a flathead screwdriver and a wrench or pliers, needed to manipulate the valves. First, locate the irrigation controller and ensure it is set to the “Off” position to prevent any zone from activating prematurely during pressurization.
Next, locate the main components of the water supply system. The primary shutoff valve for the irrigation system is often found indoors, typically in a basement, garage, or utility room, near where the water line exits the house. Also locate the backflow prevention device (BFP), which is usually an above-ground, brass or plastic assembly positioned outside.
Finally, check for any open drain valves, which are installed at low points for winter drainage. All drain valves must be closed tightly before the main water supply is turned on. Failing to secure these points will result in water escaping the system, preventing proper pressure buildup.
Gradual Pressurization of the Supply Line
The successful introduction of water into empty supply lines depends on a slow, controlled process. When water is abruptly forced into empty pipes, a hydraulic shockwave known as “water hammer” occurs. This rapid pressure surge can cause serious damage, including bursting fittings, cracking pipes, or damaging valve components.
To avoid this, the main shutoff valve must be opened very slowly. Begin by opening the valve only about a quarter of the way to allow a small, controlled flow of water to enter the system. Listen for water rushing through the pipes and allow time for the air to escape.
After waiting approximately 30 seconds for the initial surge to stabilize, open the valve another quarter-turn. Repeat this gradual process until the main shutoff valve is fully open, which should take at least two full minutes. This slow activation fills the main supply line, displacing trapped air and preventing destructive pressure waves.
Activating the Backflow Prevention Device
The backflow prevention device (BFP) protects the home’s potable water supply from contamination. It prevents irrigation water, which may contain fertilizer or pesticides, from siphoning back into the drinking water. The BFP contains multiple valves that must be activated in a specific sequence.
Before starting, ensure that the small test cocks, used for annual inspection, are closed using a flathead screwdriver. Locate the two main shutoff valves on the BFP assembly: the upstream valve (closest to the house) and the downstream valve (leading to the sprinkler zones). The process begins by slowly opening the upstream shutoff valve to pressurize the device.
Once the upstream valve is open, you may hear a brief hiss or see a small spritz of water from the vent or bonnet, which is normal as the internal check valve seats itself. Next, slowly open the downstream shutoff valve, allowing water to flow past the BFP and into the main irrigation lines. Both shutoff valves should now be fully open, with their handles aligned parallel to the pipe.
Immediately check the BFP connections and the body of the device for any visible leaks, such as steady drips or spraying water. Since this device is exposed to the elements, it is a common point of failure after winterization. If a leak is present, the water must be shut off at the main indoor valve before proceeding.
Testing Zones and Troubleshooting Common Issues
With the main lines and backflow device pressurized, the system can be tested by manually running each zone using the controller. Set the irrigation controller to the “Run” position and activate the first zone for a short duration, such as one to two minutes, allowing for a quick visual inspection.
As each zone runs, walk the area to look for immediate problems. Visible leaks manifest as geysers of water, bubbling soil, or large puddles forming rapidly near buried pipes. Check each sprinkler head to ensure it pops up fully and that its spray pattern is correct, noting any heads that are broken, stuck, or spraying onto hard surfaces.
Minor issues, like leaks at the valve box, can sometimes be fixed by tightening the solenoid cap a quarter-turn. Identify the location and type of broken sprinkler heads during this test run so that replacement parts can be sourced. Once all zones have been successfully tested, the controller can be programmed with the desired watering schedule.