Spring startup is the methodical process of transitioning an irrigation system from its winterized, dormant state back to full operation. This procedure must be executed slowly and deliberately to ensure the integrity of the underground piping and mechanical components. The primary goal is to safely fill the empty lines with pressurized water. Following a proper reactivation sequence is the best defense against pressure-related failures and damage that can lead to expensive repairs and significant water waste.
Initial System Inspection and Valve Closure
Before introducing any water, conduct a thorough visual inspection of the entire yard to identify physical damage that may have occurred over the winter. Freezing and thawing cycles can cause the ground to heave, shifting or cracking buried pipes and damaging sprinkler head risers. Look for exposed piping or heads that appear tilted, loose, or broken off.
Walk the property perimeter, examining the backflow prevention device and all valve boxes for cracks or broken fittings. Confirm that all manual drain valves, opened during winterization, are fully closed. These valves are typically found at the system’s low points and must be sealed to prevent immediate flooding. Finally, ensure the main system shut-off valve, which controls the water flow, remains completely closed.
Safely Reintroducing Water Pressure
Introducing water into an empty system requires extreme care to mitigate the risk of water hammer, a destructive pressure surge that occurs when water rushes too quickly through dry pipes. Water hammer can shatter PVC fittings or damage sensitive components by generating pressure spikes far exceeding the typical operating range of 40 to 60 psi.
The main water supply valve should be opened in small increments, starting with only a quarter-turn, to allow a controlled, slow filling of the mainline. Once the valve is cracked open, listen for the sound of water flowing and wait for it to completely subside before opening the valve further. This pause allows trapped air to escape and pressure to equalize gradually, preventing a forceful impact against the closed zone valves. Repeat this quarter-turn process until the main valve is fully open and the mainline is pressurized.
The backflow prevention device, typically located above ground, requires a specific sequence for pressurization. If the test cocks were left partially open for winter drainage, they must first be closed using a flathead screwdriver. Next, slowly open the isolation valve closest to the water source (the upstream valve) and pause to allow the backflow device to fill and stabilize. Finally, open the downstream isolation valve, which connects to the rest of the irrigation system, in a slow, controlled manner.
Zone Testing, Leak Detection, and Head Adjustment
With the system fully pressurized, manually activate each irrigation zone sequentially using the system controller. Run each zone for a few minutes to identify any damage or operational issues. As each zone runs, walk the area to check for visible signs of damage, such as geysers or persistent puddling, which indicate a broken pipe or lateral line leak.
Observe each sprinkler head to confirm it is popping up fully and distributing water as designed. Heads that fail to rise or appear clogged may need the nozzle cleaned of debris. A weak trickle may indicate a broken riser or damaged seal. For rotary heads, check that the rotating mechanism spins smoothly through its designated arc. For spray heads, verify the fan of water is uniform and not misting excessively, which suggests high pressure.
Adjusting the spray pattern ensures “head-to-head” coverage, where the spray from one head reaches the base of the neighboring head for uniform distribution. Most sprinkler heads allow simple adjustments of the arc and throw distance. Use a small flathead screwdriver or specialized tool to fine-tune the coverage while the zone is running.
Finalizing the Irrigation Schedule
After all physical repairs and adjustments are complete, establish the seasonal watering program using the irrigation controller. Start by resetting the controller’s internal clock to the correct date and time, as this data is often lost during the winter power-down. The initial spring schedule should be conservative, since plant water needs are lower than during the peak heat of summer.
Program the controller with start times, run times, and watering days based on local conditions and landscape needs. A technique known as “cycle and soak” is highly effective for lawns, running the system for multiple short intervals instead of one long session. For example, running a zone for three minutes, waiting 30 minutes for the water to soak in, and repeating the cycle three times greatly reduces runoff on sloped terrain. If the system includes a rain or soil moisture sensor, confirm it is correctly activated to override scheduled watering during or after precipitation, conserving water.