If you notice your sprinklers have lost pressure, yet they all seem to be in good working order, you probably have an irrigation system line break. Breaks in the PVC line occur for several reasons. The most common cause of line breaks is heavy downward pressure on one of the sprinkler heads. Maybe a car or lawn mower tire rolled over a head, or perhaps someone stepped on it. Repairing line breaks is a bit tricky. Finding the break is the first step to repairing it.
Turn your irrigation on, and slowly move through the zones, watching which sprinkler heads have full pressure and which ones don't. In this manner you will isolate the zone in which there is a line break.
Isolate the PVC pipe with the break by locating the wettest area, where all the water is collecting. Flag the area and turn off the irrigation.
Use your shovel and carefully remove the sod, and then dirt in the flagged area. Look for the PVC pipe as you remove the dirt. Be careful not to break the PVC pipe with the shovel.
Clear the dirt away from the PVC pipe, and locate the break.
Using the PVC cutting tool, cut the broken part of pipe away. Cut at least a 6-inch section of pipe away, regardless of how small the break is.
Using the sand paper, smooth the cut ends of pipe. Clean the pipe with PVC cleaner.
Determine how much PVC pipe is needed for the repair, including the two couplings that will be used on each end of the pipe to join it to the existing pipe.
Spread PVC cement on the end of the new pipe, and on the inside of one end of the coupling. Slide the pipe into the coupling. Repeat this process for the other end of the PVC pipe, and the other coupling.
Spread PVC cement on one end of the existing pipe in the ground, and on the inside of one of the couplings. Slide the coupling over the pipe. Repeat this process for the other existing PVC pipe in the ground.
Allow one hour of drying time, and then turn the irrigation on. Check for leaks. Replace the dirt and the sod.