The answer to 'why is my irrigation system weeds' is that a malfunctioning irrigation system can create ideal conditions for weed growth. Common issues like broken sprinkler heads, leaky pipes, or improper watering schedules can leave certain areas of your lawn consistently wet, allowing weeds to thrive.
Weeds may also take root in the soil disturbance caused by irrigation repairs or installations. Additionally, if your irrigation system is not properly calibrated, it may be overwatering certain areas and underwatering others, creating patchy growth that weeds can exploit.