The annual spring startup of an irrigation system is necessary to ensure a healthy landscape and prevent expensive damage to plumbing components. After months of dormancy, the system requires careful reactivation to transition back to full operational status. The goal of this procedure is to slowly reintroduce water pressure to the pipes, preventing a destructive phenomenon known as water hammer. Inspecting and adjusting the system now sets the stage for efficient water use and optimal plant health.
Initial Preparations and Inspection
Before any water is turned into the system, a thorough visual inspection is necessary to identify damage that may have occurred over the winter. Freezing temperatures can cause cracks in pipes, fittings, and sprinkler heads, which are often not apparent until the system is pressurized. Look for visible breaks in plastic components and check the ground around valve boxes and main lines for signs of exposed or damaged piping.
Ensure that the soil is completely thawed before proceeding with the startup. Activating an irrigation system when the ground is still frozen can lead to immediate damage to underground pipes and connections. Digging a small test hole about 12 inches deep can confirm that all frost has retreated from the subsoil.
Confirm that all drain plugs and drain valves used for winterizing the system have been closed and secured. If the system has a backflow prevention device, inspect the body for hairline cracks or splits, which are common points of failure after a freeze. Make sure the small test cocks on the device are turned to the closed position.
Safely Restoring Main Water Pressure
The most delicate part of the startup process is reintroducing water pressure to the empty main lines, which must be performed slowly to avoid water hammer. Water hammer occurs when fast-moving water suddenly stops or changes direction, creating a powerful shockwave that can burst pipes and fittings. This shockwave is capable of damaging components, including valves and sprinkler heads, leading to costly repairs.
Locate the main shut-off valve for the irrigation system, which is often near the water meter or in a basement or utility room. The process of opening this valve should take a minimum of 30 seconds to a full minute. Start by turning the handle just a quarter turn, allowing a gentle rush of water to enter the system and begin pushing air out of the pipes.
Wait for 10 to 20 seconds at the quarter-open position, listening for the sound of the pipes filling to subside as air escapes and pressure equalizes. Once the initial rush has quieted, slowly turn the valve further to the halfway point, waiting again for the flow to stabilize. Continue this gradual process until the main valve is completely open.
Next, the backflow prevention device must be activated by slowly opening its two main shut-off valves, which are typically ball valves. If the device has a lower and upper valve, open the lower one first, followed by the upper one, performing this action slowly to manage the pressure increase. This deliberate, measured approach ensures the system fills with water at a safe speed, protecting the integrity of the underground network.
Checking and Adjusting Sprinkler Zones
Once the main lines are pressurized, manually activate each zone sequentially to check for proper function and leaks. Use the system’s controller to initiate a manual or test run for a short duration, such as two minutes per zone. As the first zone turns on, listen for sputtering noises, which are normal as remaining air is flushed from the lateral lines through the sprinkler heads.
Walk the zone while it is running, looking for water pooling or bubbling from the ground, which indicates a leak in the underground piping or a broken valve seal. Pay close attention to the sprinkler heads, ensuring they pop up to their full height and that water is not leaking excessively from the base. Debris like dirt or sediment can settle in the lines over winter, potentially clogging the nozzle openings.
If a head is not spraying correctly, gently adjust its position to ensure it is perpendicular to the ground and aimed correctly, avoiding sidewalks and driveways. For spray heads, the arc and radius can be fine-tuned using a flathead screwdriver inserted into the adjustment screw. If a head is significantly clogged or damaged, it may need replacement, though removing the nozzle for a quick flush might clear minor debris.
Setting the Irrigation Controller
The final step is to program the irrigation controller with a schedule appropriate for the early spring growing season. Verify that the controller has the correct current date and time set, as winter power outages may have reset the internal clock. If the controller uses a backup battery, consider replacing it if it is more than six months old to maintain programming memory.
Select the appropriate start time for the watering cycle, ideally scheduling it for the early morning hours (between 2 a.m. and 6 a.m.) to minimize water loss from evaporation. Watering during this period allows the water to soak into the soil before the heat of the day and permits the grass blades to dry before evening, reducing the risk of fungal disease.
Set the run times for each zone, noting that spring needs are significantly less than summer requirements. Reduce the full-summer run times by about 50 percent for the spring months. For example, if a zone runs for 20 minutes in the summer, set it to 10 minutes in the spring, using a reduced frequency of one to two days per week, depending on local rainfall. If the controller has a seasonal adjustment feature, this can be used to scale back the entire schedule on a percentage basis.