A damaged sprinkler line that sits under concrete should be repaired right away because a leaky supply line can lead to severe problems with the sprinkler system. If your pipe has sprung a leak, you must remove the damaged section of pipe and replace it was a new one. Leaving a leaky pipe under concrete also can damage the surface over time and lead to cracks and sunken sections of concrete.
Things You'll Need
Section of new PVC pipe
2 PVC couplers
Dig up the area on both sides of the concrete until you expose the supply pipe. Remove enough dirt so that there is at least a 3- to 4-foot section of the pipe exposed on both sides. This will give you enough room to work with the pipe.
Shut off the water to the sprinklers at the main ball valve.
Cut off the pipe on both sides of the concrete using a hacksaw. Make the cut at least 1 foot away from the edge of the concrete so you have enough room to maneuver the new pipe.
Pull the damaged pipe out from under the concrete. This may require the help of a second person to pry the pipe out from under the concrete. Pull straight back rather than at an upwards angle.
Cut a new section of pipe at the same length as the damaged section.
Place one end of the pipe into the hole where the damaged pipe was located and press it under the concrete until it pops out the other side.
Wipe off the dirt from both of the exposed ends of the pipe and apply a thin layer of PVC primer to both ends to clean the connection points.
Swab one end of the pipe with PVC glue and then press a PVC coupler onto the end of the pipe. Swab the end of the exposed section of pipe that you cut from with PVC glue and press the other end of the coupler onto the pipe. This will seal the connection on one end of the concrete. Repeat the process on the other end of the concrete to attach a second coupler to the new section of pipe and the original supply line to complete the connection.
Allow the new fittings to dry for at least two hours before covering the pipe back with dirt and turning the water to the sprinklers back on.
Cut PVC pipe can be sharp, so use caution when handling cut pipe.