A simple item to include in the inspection is leaks. Pipe joints may leak if a glue joint or gasket is bad. A damaged pipe, broken riser or other part may have failed.
Leaks mean a loss of water and pressure, not to mention runoff on the ground.
Clogging of pipelines
Depending on water quality and presence of algae, there is a possibility of pipeline clogging which will restrict water flow. Drip systems are pone to have clogged emitters if dirt or algae are in the water. Watch for sprinkler heads or emitters that are not working properly, that may indicate a problem with water delivery.
Look at the application patterns to see if any problems can be seen. Clogged emitters or sprinkler nozzles should give themselves away by a look at the crop. Clogged drip emitters in a container growing area will show a wilted or dead plant if the situation is not found soon. Overhead sprinkler application patterns may not be so obvious to the eye but over time crop growth may be less in some areas due to less water received.
Sprinklers may not have their arc adjusted properly to give the correct radius of throw. This is usually an easy to correct situation, if the sprinkler has an adjustment.
Matched precipitation Sprinklers
Over watering at corners or a long the edge of a large growing area may occur if matched precipitation nozzles are not used. The water application pattern should show extra water in these areas if the nozzles are not correct.
Inspect a few containers for moisture
If you notice containers in which plants are not doing very well, check the moisture level in them compared to containers with plants that are doing well. Is there a noticeable difference in the substrate moisture? One reason for doing an audit is to check the uniformity of application and notes on any visual problems are good to have. The goal is to reduce that problem.