Homeowners often need to relocate existing sprinkler lines when undertaking significant outdoor projects, such as installing a new deck, changing landscape beds, or adding a swimming pool. Moving these lines successfully requires a systematic approach to maintain water efficiency and system integrity after the alteration. This relocation process involves careful planning, precise cuts, and secure connections to prevent future leaks or pressure issues. Following a detailed, step-by-step method allows the DIYer to confidently manage this plumbing adjustment.
Preliminary Planning and Safety Checks
Before starting, map the exact route the relocated line will take and mark the precise placement of new sprinkler heads. This map should account for necessary burial depth, typically 8 to 12 inches below the surface, to protect the pipe from garden tools and surface weight. Contacting the local utility location service (“Call Before You Dig”) several days prior is a fundamental safety requirement. These services mark underground gas, electrical, and telecommunications lines, preventing accidental strikes during excavation.
Identifying the existing system material—Polyvinyl Chloride (PVC) or Polyethylene (Poly)—dictates the required fittings. PVC systems require rigid couplings, elbows, and T-junctions, along with specialized solvent cement for bonding the pieces. Polyethylene pipe utilizes barbed fittings secured with metal hose clamps for a mechanical, watertight seal. Locate the main backflow preventer or system supply valve to completely isolate the system from the household water supply. Open the system drain valve to fully depressurize the lines, ensuring no residual water or pressure remains before cutting any pipe.
Excavation and Isolating the Old Line
The physical work begins with careful excavation, especially when digging near the existing sprinkler line or marked utility lines. Hand digging is strongly recommended when working within 18 inches of identified underground infrastructure to minimize the risk of damage. Once the existing pipe is exposed, choose a section of the main line where the new lateral run will branch off, typically requiring a T-junction fitting.
The existing pipe must be cut cleanly and squarely to ensure a proper mating surface for the new fitting. For rigid PVC pipe, a ratcheting pipe cutter provides the cleanest edge, while flexible Polyethylene pipe can be cut with a sharp utility knife or specialized poly cutter. After the cut is made, the pipe ends must be meticulously prepared to facilitate a strong, leak-free connection. PVC pipe ends should be deburred, sanded lightly to remove the glossy surface, and chamfered slightly on the outer edge to allow the fitting to slide on smoothly. This preparation ensures maximum surface area contact for the solvent cement to chemically fuse the plastic molecules together. For Poly pipe, ensuring the cut is free of dirt and debris is paramount before inserting the barbed fitting.
The trench for the new line should also be dug to the required depth at this time, maintaining a smooth, consistent grade to prevent air pockets or low spots in the new piping.
Installing and Connecting the New Piping
With the existing line prepped, begin installing the new piping run at the connection point. When working with PVC, apply a primer to both the exterior of the pipe and the interior of the fitting, which softens the plastic surface. Quickly apply solvent cement, insert the pipe into the fitting with a slight twist, and hold the connection firmly for about 30 seconds to allow the chemical fusion process to begin.
For Polyethylene pipe, insert the appropriate barbed T-fitting into the cut ends of the existing line, and push the new section of pipe onto the third barb. Position a stainless steel clamp over the fitting and tighten it securely using a screwdriver or nut driver. Lay the new pipe in the prepared trench, following the mapped route and maintaining the specified burial depth. Long, sweeping curves are preferred over sharp angles to minimize friction loss and maintain optimal water pressure throughout the line.
Attach the sprinkler heads at the terminus of the new line using a connection that incorporates flexibility. Install a swing joint or a short section of flexible pipe to connect the rigid lateral line to the sprinkler head riser. The swing joint mechanism allows the sprinkler head to move slightly if stepped on or hit by equipment, preventing the rigid mainline connection from snapping under mechanical stress.
Before backfilling any trench, assemble and secure all new connections to create a continuous, watertight system. Ensure all swing joints are properly threaded and tightened, and that the head risers are vertical and flush with the final desired grade.
System Testing and Final Burial
The final stage involves verifying the system’s functionality and restoring the area, beginning with a careful pressure test. Turn the main water supply back on slowly to allow the system to gradually fill with water and equalize pressure. This prevents a sudden surge that could stress the new connections. With the trenches still open, visually inspect all new fittings and joints for any signs of weeping or leakage under static pressure.
Once static pressure holds, activate the specific zone connected to the new line via the controller. Running the zone allows for a dynamic pressure check and verification of the relocated sprinkler heads’ coverage and spray pattern. If the pressure appears adequate and no leaks are observed, the sprinkler heads can be adjusted to ensure they cover the intended area efficiently without overspray. Backfill the trenches by adding soil in layers and lightly tamping each layer down to prevent future settling of the ground. This careful tamping process is important to stabilize the pipe and protect it from displacement.