Anyone with a sprinkler system knows leaks, drips, and full-on blowouts can happen at any time, regardless of the season or your watering schedule (but Murphy's Law seems to ensure it’s usually at night when it's cold and raining). So, when you see or hear the gushing, bubbling water where it shouldn't be, here's an easy and inexpensive fix that will keep the water flowing in the right direction.
Step 1 - Expose the Pipe
Start by turning the water off at the source so you're not wasting water or creating a larger mess. Depending where the break is and the force of the water, it may not take much work to clear access to the pipe, as the leak may have already blown the dirt aside. You still need to clear enough dirt away so the pipe is exposed for about a foot.
Sometimes it takes a few tries to find the actual source of the leak, since water may run and pool in a different location. If it isn't obvious where the break is, expose some of the suspected pipe and turn the water back on to observe leaks.
Use caution when digging to avoid breaking the line in another place. Also be sure to check with your local utility line identification service company so you don't accidentally dig through cables or gas lines.
Remove the sprinkler after you do this to minimize the amount of dirt that gets inside it.
Step 2 - Cut the Pipe
Once you've identified the break in the line, you'll need to remove the broken parts in order to replace them with new pieces. Always check where the pipe meets a fitting, as this is a common area for leaks. However, something like roots could also cause problems in the middle of an underground waterline.
A PVC cutter will cut down on vibrations while you work, but if you don't have one a reciprocating saw works well.
Cut the away pipe a few inches on either side of the fitting, assuming that is the problem location. The same practice applies to other stretches of broken pipe.
Step 3 - Find the Fittings
If you have parts on hand, just match them up with what you cut away. If not, take the fitting to the home center and find one that matches. Pay attention to diameter for a proper fit. You also need two straight connectors and a short length of pipe, all of the same diameter as the original. You may have to shuttle back and forth between the plumbing department and the garden/irrigation department to find everything you need. Don’t forget PVC glue. For a single pipe, a small container will do the trick.
Step 4 - Size the Replacements
Cut a few inches off the new length of pipe and attach it to one end of the fitting. Attach a straight connector to the other end. Hold this assembly up to one end of the broken pipe, figuring it will fit half way into the connector. On the other end of the broken pipe mark how long it needs to be to match up with the fitting and cut it there. If you made a larger gap in the pipe, you may need a length of replacement pipe and a straight connector on both sides of the fitting.
Step 5 - Replace the Fittings
This can be a bit of a puzzle because everything fits together with very little slop. However, this step is essential in completing a repair job that will last without leaking or causing a blow out. Try different techniques to set the pieces in place. Try fitting onto one end of the pipe and then attach the connector to the other end. You can bend the pipe slightly to get it to snap together. Dry fit everything to make sure it matches up.
If it matches up, pull it apart and then repeat the process, first putting PVC glue on the outside of the pipe and the inside of the fitting and connectors.
Step 6 - Reattach the Sprinkler and Bury It
The PVC glue sets up almost instantly, so work quickly to get things in place. Follow the directions on the container for curing time and then turn the water on to ensure a leak-free seal. Be sure to either cap off the sprinkler head or expect to see water shooting out. The goal is to check the pipes before covering them back up. Finally, reattach the sprinkler parts and fill in the hole, leaving the top of the sprinkler exposed.
Finally, sleep well, knowing you’ve averted another geyser in the wee small hours of the morning.