Sprinkler head not popping up — San Diego, California

When one or more pop-up sprinkler heads fail to rise during a watering cycle while the rest of the zone operates normally, the cause is almost always localized to that head or its immediate supply line rather than a system-wide pressure problem. The most common culprit is dirt, sand, or grass clippings packed around the riser mechanism: over time debris works its way between the retractable nozzle body and its housing, creating friction that the water pressure can no longer overcome. Removing the head, cleaning the riser and internal screen, and reinstalling it solves the problem in most cases. The second most frequent cause is a cracked or crushed riser body — pop-up heads sit at grade level and are regularly hit by mower wheels, foot traffic, and vehicle tires, which can crack the plastic body or bend the internal spring mechanism so the head physically cannot rise. Replacement heads cost $3–$15 for residential spray or rotor types and take 10–15 minutes to swap. Less commonly, the supply line fitting directly below the head may be broken or the lateral pipe may have a leak upstream of the head, reducing pressure to zero at that nozzle while other heads on the same zone still receive enough flow. Signs of a supply-line break include a persistently soggy patch of lawn near the head even when the system is off, and sometimes the head will partially pop up but spray weakly or at an odd angle. A landscaper or irrigation specialist can diagnose the issue by running each zone while inspecting head-by-head, checking for leaks at the riser fitting, measuring zone pressure, and replacing heads or repairing pipe sections as needed.