How to Install an In-Ground Sprinkler System

Installing an in-ground sprinkler system takes time and sweat equity, but it is worth it. You’ll need to tie in your home’s water supply, install a valve box and manifold, lay out all the underground pipes, and attach sprinkler heads.

This is one of those projects that can feel very exhausting when you’re in the middle of it, but once it’s all done and the system is up and running, it will make a massive difference in the health of your lawn and decrease your water consumption.

Note: Some people are nervous about tying an irrigation system into their home’s main water supply. If that’s the case and you’d rather not tackle these plumbing steps, hire a licensed plumber. Have someone come out, tap into your main supply, and install a shut-off valve. You can then complete the rest of the sprinkler system installation.

Supplies and Tools Needed

  • Irrigation controller
  • PVC or polyethylene pipe for the mainline and lateral lines — should be at least three-quarters of an inch
  • Elbows, tees, couplings, connectors, and any other fittings needed to assemble the water line
  • Sprinkler heads
  • Risers
  • Shut-off valve
  • Backflow preventer (if required by local code)
  • Sprinkler manifold — needs one valve per system zone; you can build your own or buy a prefabricated unit Valve box large enough to house the sprinkler manifold
  • Pipe wrench
  • Pipe cutter or hacksaw
  • Pipe cement
  • Plumber’s pipe tape
  • Trenching tools (shovels or a trenching machine)
  • Landscaping flags or spray paint
  • Miscellaneous tools, including a level, pliers, screwdriver, wire cutters, and wire connectors

Step-By-Step Sprinkler System Installation Instructions

  1. Lay out the design in the lawn: Using spray paint, mark where the trenches will run and use landscaping flat to pinpoint where each sprinkler head will be installed. You should also mark out where you want to install the valve box. It must be between the shut-off at the main supply and the sprinkler heads.
  2. Dig the trenches: Start closer to the house where you’re connecting to the main water source and move outward across the lawn. Use the trenching machine (a ditch witch) or a shovel to dig trenches for the mainline and lateral pipes. Trenches should be about four inches wide and eight to 12 inches deep, and the bottom should be level.
  3. Tie into your main water supply: Connect to an existing faucet or tap into the service line, depending on your climate. If you live in a cold environment, you’ll want to tap into the service line; in warmer climates, you can avoid cutting into the pipes and tie in at an existing faucet. Make sure to shut off the water supply to your home before doing any work.
  4. Install a shut-off valve and backflow preventer: Once you have tied into the main water supply and have a separate line running to your sprinkler system, install a shut-off valve to make repairing or maintaining the sprinkler system easier. If local code requires it, install a backflow preventer at least 12 inches above the soil surface. A backflow preventer keeps water flowing in one direction and prevents contamination of your household drinking water.
  5. Install the valve box and sprinkler manifold: Dig a hole slightly wider than the outside of the valve box and set it securely in the ground. The lid should rest slightly below or right about ground level so you don’t hit it when cutting the grass. Position the valve manifold within the box, lining up the inlet and outlet pipe openings with the holes in the sides of the valve box. Run a pipe from the shut-off (or backflow preventer) at the main through one side of the valve box, attaching it to the valve manifold.
  6. Lay out and connect the pipes: Start at the valve box and work outward through the lawn. Assemble the pipe sections and place them in the trenches. If you’ve never worked with PVC cement before, take a few minutes to look at some online tutorials to become familiar with the process. The cement sets within 30 seconds, making it essential to know what you’re doing and work quickly.
  7. Install the sprinkler heads: Once the mainline and lateral supply lines are assembled and laid in the trenches, it’s time to install the heads. Wrap the connection threads with pipe supply tape and screw a riser onto the connection in a clockwise direction, making sure to only hand tighten it. Then screw the head on in a similar fashion.
  8. Install the irrigation controller: Turn off the electrical at your main panel, and follow the user manual instructions to mount the controller on the garage wall or somewhere it is protected from the elements. Keep in mind the controller needs to be closer to a power source. Once installed, run wires from the controller to the valve manifold and make the appropriate connection.
  9. Test the sprinkler system: Turn the water back on, plug your controller into an outlet, and turn the system on. Carefully observe the entire lengths of the pipe and all of the connections, including where the sprinkler heads attach for leaks. Have each sprinkler head pop up and drop back down several times to ensure they aren’t catching on any obstructions.
  10. Bury the pipes: When you’re satisfied everything is installed correctly and running, turn the sprinklers off and backfill the trenches. Tamp down or roll the soil to get rid of any air pockets.
  11. Program the controller: Using the operating instructions, enter all of the watering parameters into the controller, including days to water, start time, and station run times.
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