How to Repair Water Lines in an RV

Turn off the RV's water pump and open the faucets around the leak to drain the water line.

Cut out the damaged section using a pocket knife for plastic tubing or a PVC saw for PVC piping.

Cut a new section of tubing or piping the same length as the damaged section to serve as a replacement. In the case of a plastic tube with plenty of slack, this might not be necessary.

Patch up the water line. For a plastic tubing with plenty of slack, you can do this with one fitting. Fittings for plastic tubing are often of the push-in or screw-in variety, so simply put the two ends of the severed line into a single fitting. For plastic tubing with no slack, use two fittings attached to the ends of the severed water line and a new section of tubing inserted between them. For PVC piping, use the two fittings and a new section of tubing between them again, fastening it all together with PVC adhesive.

Allow the PVC adhesive to dry overnight, if it was used.

Switch the water pump back on, open faucets around the repaired area and check for continued leaks. There might have been a flaw in how your did the fittings or perhaps another leak you did not detect.