If a zone has low pressure while other zones are normal, what is a likely cause?

A likely cause of low pressure in one specific zone while other zones are functioning normally is indeed a leak or blockage in that zone's lateral line. Lateral lines are responsible for carrying water from the main line to the individual sprinkler heads or emitters. If any part of this system experiences a blockage—such as dirt, debris, or a physical obstruction—or if there is a leak, it can restrict the flow of water, resulting in lower pressure in that particular zone.

When checking for issues in the irrigation system, it is essential to monitor each zone individually. If low pressure is evident in just one zone, it typically indicates a localized issue rather than a systemic problem affecting the entire irrigation setup. Other potential causes, while they may affect the overall system, would not likely result in low pressure confined to just one zone.

Inadequate power supply to the controller would generally affect all zones rather than isolate the problem to just one, while clogged mainline pipes would cause pressure issues throughout the system. Faulty master valve operation would also impact multiple zones rather than isolate the issue to a single area. Thus, a leak or blockage in that zone’s lateral line is the most plausible explanation for low pressure in that specific zone.