The answer to 'sprinkler system yellowing' is that it is often caused by a buildup of mineral deposits or chemical imbalances in the water supply. This can lead to discoloration and corrosion of the sprinkler heads and pipes, resulting in a yellowish appearance. Symptoms may include reduced water pressure, uneven coverage, and a decline in the overall health of your lawn and landscaping.
In many cases, this issue can be resolved through a combination of regular maintenance, flushing the system, and adjusting water treatment or filtration. However, more complex problems like broken components or system design flaws may require the expertise of a professional landscaping technician.