How to Install an Underground Sprinkler System


Underground sprinklers can help promote a healthy look for your yard and gardens. They can be programmed with starting and ending times, simplifying the watering of your gardens, shrubs, trees and yard. Plus, underground sprinklers provide even watering for a professional look about your yard that enhances its growth and coloring.

Things You'll Need

  • Graph paper and pencil
  • Shovel
  • Wrench
  • Utility knife
  • PVC or CPVC pipe
  • PVC or CPVC male adapters- 1 for each sprinkler head, 2 for each automatic drain valve, and 5 the underground pipe from the outside pipe
  • PVC or CPVC T-fittings
  • PVC or CPVC risers
  • PVC or CPVC fittings
  • PVC or CPVC elbows
  • Hacksaw or tubing cutter
  • Anti-siphoning valve
  • Gate valve
  • Iron or steel T-fitting, threaded
  • Iron or steel close nipple
  • Automatic drain valves (one for each branch and one for the end of the pipe run)
  • Gravel
  • Sprinkler heads
  • PTFE plumbers' tape
  • Plastic electrical tape
  • Solvent glue and primer
  • Plastic solvent cement
  • Pen


  • Do your research and find out if your township or county has restrictions related to underground water systems. Inquire after the need to obtain any permits.

  • Contact the local water department about the existence of underground pipes. Make a note of them on a diagram of your yard.

  • Contact local electrical, telephone, and gas departments about the existence of underground wiring or pipes. Make a note of them on a diagram of your yard.

Planning Stages

  • Determine the water pressure using a pressure gauge at an outdoor faucet.

  • Determine the flow rate or how much water your water system provides per minute.

  • Plan the positioning of your sprinkler system on a diagram, overlapping the spray.

  • Determine the number of sprinkler heads and the size and type of pipes that you need to purchase, using measurements of the area where you will be installing the underground sprinkler system. Ask for help at the store if you are unsure what to purchase.

  • Purchase the parts for your underground sprinkler system.

  • Install a shut-off valve for the outside water as well as a drain so that you can shut the water off and drain the system in the winter. This will help to prevent costly damage.

Working with the Existing Faucet

  • Cut the pipes to the proper length for your design.

  • Turn the outside water off.

  • Take off the outside faucet.

  • Put the iron T fitting on securely.

  • Put the iron close nipple into the proper opening. This is the one that is pointing out straight.

  • Replace the faucet.

Working with the Anti-Siphoning Valve

  • Measure the lengths of PVC or CPVC pipe for placement at the faucet.

  • Cut the pipes.

  • Attach a male adapter.

  • Cover the threads of the adapter using PTFE plumber’s tape.

  • Screw one of the pipe pieces into the iron T fitting’s opening. It should be pointing downward.

  • Attach the second piece of pipe to the first one using an elbow.

  • Attach the anti-siphoning valve to the other male adapter.

Working with the Gate Valve

  • Cut a small piece of pipe, attaching a male adapter to each end.

  • Using PTFE plumber’s tape, cover the threads of the adapters.

  • Attach an end of the pipe to the gate valve and an end to the anti-siphoning valve.

Digging and Linking the Gate Valve to the Pipes

  • Map out the digging area. Prepare the ground by laying tarps for the sod and dirt that you remove. Make the trenches as wide as the shovel and 9 inches deep. Increase the depth ¼ of an inch every 5 feet.

  • Mark the placement for your sprinkler heads.

  • Place gravel inside the trenches.

  • Measure and cut the pipe that connects the gate valve to the bottom of the trench.

  • Use PTFE plumber’s tape and cover the threads of the adapters, attaching the male adapter and elbow.

  • Attach the pipe to the gate valve and attach the elbow at the beginning of the pipe run.

Laying the Pipe Run

  • Measure and cut your pipe.

  • Lay your pipe into the gravel-lined trenches, attaching elbows at corners and T fittings at branches.

  • Attach automatic drain valves at the end of branches and runs.

Attaching the Sprinkler Heads

  • Prepare the risers, cutting them to size.

  • Using solvent glue, attach the adapters to the risers. Allow this to dry. Use PTFE plumber’s tape to cover the threads.

  • Attach the T fittings to the risers, placing a stake next to it.

  • Put the sprinkler heads on.

Tips & Warnings

  • Select either PVC or CPVC pipe for your underground sprinkler system. These types of pipe are easy to use and lightweight; and they won’t corrode.

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