The transition from a winterized irrigation system back to operational status requires a controlled process to safeguard plumbing and mechanical components. During winterization, water is purged from the lines, and the system is depressurized. If water is reintroduced too quickly, a sudden surge of pressure can cause catastrophic failures, such as bursting weakened pipes or damaging the sensitive backflow prevention device (BFP). Following a methodical startup procedure ensures the longevity of the system and prevents costly repairs.
System Preparation and Inspection
Before reintroducing water, it is necessary to confirm the closure of all drain points used during winterization. Any manual drain valves, often located at low points in the system, and any manual bleed screws on individual zone valves must be securely tightened. Leaving these open will prevent the system from building pressure and can lead to immediate flooding when the water supply is restored.
A comprehensive visual inspection of the exposed components should be performed while the system is still dry. Look carefully at above-ground piping, especially around the backflow prevention device, for any signs of cracks, splits, or separation caused by residual frozen water. Even hairline fractures can turn into significant leaks under full operating pressure, necessitating immediate repair.
Check all visible sprinkler heads and risers for evidence of shifting, tilting, or damage from snowplows or ground movement over the winter months. Ensure the main water shutoff valve, typically a ball valve or gate valve located near the meter or inside a utility area, is fully accessible. Having clear access to this valve is important should an unexpected leak require immediate shutdown during the pressurization process.
Gradual Water Restoration
The most important step involves slowly opening the main water shutoff valve to allow for controlled pressurization. Open the valve in quarter-turn increments, pausing between each turn, rather than opening it fully at once. This measured approach permits air trapped in the mainline to escape gradually through the system’s various components, preventing a damaging phenomenon known as water hammer.
Water hammer occurs when a sudden stop or start of water flow creates a pressure wave that travels back through the pipes, potentially exceeding the pressure rating of the components. By slowly filling the pipes, the water gently pushes out the air pockets that formed during winterization. Listen intently for hissing sounds, which indicate air escaping, and gurgling noises, which often signal water filling a large void or chamber within the system.
Once the mainline is partially pressurized, attention shifts to reactivating the backflow prevention device (BFP). For common types like Pressure Vacuum Breakers (PVBs), the lower ball valve closest to the water source is opened first, followed by the upper ball valve closest to the irrigation system. This sequence ensures a gentle flow through the internal check valves.
Allow the BFP to fully pressurize and check the test cocks for small leaks or drips before fully opening the second valve. Sudden pressure changes can damage the internal seals or springs of the BFP, requiring professional re-certification. Consulting local regulations regarding the mandated annual testing of these devices is a prudent step.
Zone Testing and Adjustment
With the mainlines fully pressurized and confirmed leak-free, the next step is to activate each individual watering zone. This is typically done by running a brief manual cycle directly from the system controller or by activating the solenoids manually at the valve box. Activating zones sequentially allows for isolation and specific observation of each segment of the system.
As each zone runs, observe the water flow and pressure carefully, looking for evidence of major breaks, like geysers of water, or continuously running valves. A zone that fails to turn off or exhibits extremely low pressure compared to others may indicate a stuck solenoid, a ruptured lateral line, or a diaphragm failure within the zone valve itself. These issues require immediate system shutdown and repair before proceeding.
After confirming the basic functionality of the zone valves, inspect the performance of individual sprinkler heads within that active area. Look closely at the spray pattern, noting any streams that are misting excessively, which suggests a possible blockage or a damaged nozzle. Tilted heads or those sunken into the turf should be straightened or raised to ensure they reach their intended coverage area.
Use the appropriate tool to adjust the arc and radius settings of the heads, ensuring water is landing on the landscape and not on sidewalks or driveways. Clogged nozzles can often be cleaned using a small wire or by temporarily removing the nozzle itself to flush out trapped debris. Correcting these minor issues now maximizes water efficiency throughout the season.
Finally, reset the system controller with the appropriate seasonal watering schedule. Start with conservative run times, typically shorter cycles repeated several times to allow for maximum soil absorption and minimal runoff. Adjust the system’s clock, day settings, and start times to reflect the current growing conditions and the local water restrictions for the spring season.