Turning a sprinkler system back on is not just opening a valve. Do it too fast and you can blow a fitting that survived the whole winter fine. Here is the order we work in, and what to look for at each step.
Wait for the ground to thaw
If there is still frost in the soil, the pipes are not ready to take pressure. In most of Western Washington that means mid March into April, depending on the year and how exposed your yard is.
Open the main valve slowly
This is the step people rush, and it is the one that causes damage. Air in an empty line moves fast, and when water hits it at full pressure the surge can crack fittings that would have been fine otherwise.
Open the valve maybe a quarter turn and let the system fill gradually. You will hear the lines charge. Once the noise settles, open it the rest of the way.
Walk every zone
Run each zone one at a time and actually walk it. What to look for:
- Heads that do not pop up. Usually debris in the riser, sometimes a cracked body.
- Heads spraying the driveway or the fence. Winter shifts things. Arcs need adjusting most springs.
- Mist instead of a stream. That is pressure too high, and it wastes a surprising amount of water to evaporation and drift.
- A zone that will not start. Most often a solenoid, a wiring break, or a valve stuck from sitting all winter.
- Soggy ground with no head running. That is a leak underground, and it will not fix itself.
Check the backflow preventer
Look for cracks, drips, and weeping at the fittings. This is the part most likely to have been damaged over winter, and a slow leak here can run for weeks before anyone notices.
Reset the controller
The backup battery has probably died and the schedule may have reset. While you are in there, set the schedule for spring rather than whatever it ran last August. Cool wet spring weather needs far less water than a dry summer, and most systems in this region are set to overwater in April.
Watch the first full cycle
Let the system run its whole schedule once while you are home. Problems that do not show in a two minute test show up in a full cycle: pressure dropping across zones, a head that sinks under load, an area that stays dry.
When to call
If a zone will not run, if you find soggy ground with no obvious source, or if the backflow preventer is leaking, that is repair territory rather than adjustment. Those are diagnostic jobs, and guessing at them usually costs more than the visit.