The answer to 'why is my sprinkler system yellowing' is that your sprinkler heads or pipes may be corroded or clogged, causing mineral buildup and discoloration. This is a common issue that can happen over time as the system ages and minerals accumulate.
Some common causes of sprinkler system yellowing include hard water, high iron content in the water supply, and exposure to the elements. The yellow or orange discoloration is typically a sign of mineral deposits or rust. This can restrict water flow and lead to uneven coverage or dry spots in your lawn.