What should you do first if a sprinkler won't shut off?

In a situation where a sprinkler won't shut off, the immediate priority should be to ensure safety and prevent water wastage. Therefore, shutting off the mainline is the most logical first step. This action stops the flow of water to the entire irrigation system, preventing further overflow or flooding while you investigate the problem.

After the mainline is shut off, you can safely assess the sprinkler to identify the issue without the added concern of water continuing to run. Common issues might include a malfunctioning valve or a damaged sprinkler head, and these can be addressed without water flowing through the system. Taking this precaution first helps manage any potential damage or inefficient use of water resources effectively.