Plugging a sprinkler line involves sealing a section of the irrigation system, either to permanently remove a sprinkler head or to repair a leak in the pipe itself. This process requires careful preparation and the selection of materials appropriate for the pipe type, typically rigid Polyvinyl Chloride (PVC) or flexible Polyethylene (Poly) tubing. Proper execution ensures a secure, leak-free repair that maintains pressure for the rest of the system.
Essential Preparation Before Starting Work
The first step is to locate and shut off the main water supply to the irrigation system or the specific zone that requires work. This isolates the damaged section and prevents a high-pressure geyser once the pipe is cut. The main valve is often found near the backflow preventer or where the sprinkler line connects to the main water service line.
After closing the main valve, relieve any residual pressure in the line by opening a test head or a drain valve on the affected zone. This prevents water from flooding the repair area. Once the water flow has stopped, gather tools like a shovel or trowel for excavation, a PVC cutter or hacksaw, and rags to clean the pipe ends.
Methods for Decommissioning a Sprinkler Head
Permanently removing a sprinkler head requires capping the line to prevent water from escaping when the zone is active. The method used depends on whether the line is PVC or flexible Polyethylene pipe. You must first dig around the sprinkler head to fully expose the pipe fitting beneath the soil.
If the pipe is rigid PVC, the sprinkler head or riser is typically threaded into a tee fitting and can be unscrewed. Once the head is removed, install a correctly sized threaded cap or plug directly into the tee fitting to seal the opening. Using Teflon plumber’s tape on the threads before installation helps ensure a watertight seal against the system’s operating pressure.
For a flexible Polyethylene line, the process involves removing the head, cutting the pipe, and inserting a specialized barbed fitting. Cut the pipe cleanly past the riser connection and insert a barbed end-plug fitting into the open end of the Poly tubing. A stainless steel clamp must be secured over the fitting and tightened to compress the flexible pipe onto the barbs, preventing the plug from blowing out under pressure.
Repairing and Plugging a Damaged Main or Lateral Line
When a leak occurs mid-line due to a puncture or crack, cut out the damaged section and splice in a new piece of pipe. For PVC pipes, the most effective solution is a slip-fix coupling, also known as a telescoping repair coupling. This fitting allows you to replace the section without having to flex the rigid pipe, which is often impossible in a small trench.
To use a slip-fix coupling, cut out the damaged pipe section, ensuring the remaining gap is slightly shorter than the fully extended coupling. Apply PVC primer to both the inside of the coupling ends and the outside of the existing pipe ends, followed immediately by PVC cement. The slip-fix slides onto one pipe end and telescopes across the gap to be cemented onto the other end, creating two sealed joints.
Repairing a flexible Polyethylene line involves using barbed couplers or compression fittings to join a new section of pipe. After cutting out the damaged area, insert a barbed coupling into both the existing pipe and the new piece of Poly tubing. Secure each connection point with a stainless steel hose clamp, tightening it over the barbs of the fitting to prevent leaks. Replacing the section with a coupling is generally more reliable for a permanent fix than using temporary repair epoxy or a patch kit.
Final System Check and Flushing
Once the plug or repair is completed and the cement or clamps are set, slowly repressurize the system. Return to the main shut-off valve and open it gradually, allowing the water to fill the lines and compress the air within the system. Opening the valve too quickly can cause a pressure surge that may damage the new repair or other vulnerable parts of the system.
After the line is fully pressurized, carefully inspect the repair site for any signs of leaks, such as dripping water or bubbling in the soil. Run the zone for a few minutes to flush out any debris, such as soil or PVC shavings, that may have entered the pipe during the repair process. This prevents the debris from clogging a sprinkler head downstream.