How to Install an In-Ground Sprinkler System
Map zones, dig trenches, connect supply manifolds, lay poly pipe, and calibrate pop-up sprinkler heads to build a fully automated lawn irrigation system.
- Read the tools, materials, safety notes, and steps below for free.
- Tap Start Camera Coach when you want hands-free voice help.
- Allow camera and microphone. Point your phone at the work; the coach watches your progress and tells you the next step.
🧰 Required Tools & Equipment
- ✓ Trenching shovel or walk-behind trencher
- ✓ Irrigation pipe cutter
- ✓ Crimp ring tool or nut driver
- ✓ Wire strippers
- ✓ Torpedo level
- ✓ Marking spray paint
📦 Materials & Supplies
- ✓ Flexible polyethylene pipe (3/4-inch or 1-inch)
- ✓ Pop-up sprinkler bodies and spray nozzles
- ✓ Barbed tees and elbow fittings
- ✓ Stainless steel crimp clamps or worm-gear hose clamps
- ✓ Automatic irrigation valves with manifold
- ✓ Waterproof multi-conductor irrigation wire
- ✓ Swing pipe (funny pipe) and spiral barb fittings
⚠️ Safety Checkpoints & Warnings
- • Call 811 (Utility Call Before You Dig) at least 48 hours prior to excavating to mark underground power, gas, and communications lines.
- • Shut off the main water shutoff valve and verify zero pressure at an outdoor spigot before cutting into existing plumbing lines.
- • Install a certified backflow preventer according to local plumbing code to stop non-potable lawn water from siphoning into drinking water.
📋 Step-by-Step Guide (7 Steps)
Mark Trench Paths and Head Locations
Walk the yard and mark head locations with survey flags ensuring head-to-head spray coverage overlap. Use marking spray paint to outline the direct trench routes connecting the water source to the valve manifold and each sprinkler head. Avoid root systems and ensure paths stay clear of marked utility flags.
- • Continuous brightly painted lines tracing the yard connecting all flagged sprinkler head spots.
- • Color-coded flags planted at every planned pop-up location showing 100% overlapping coverage radius.
- • Spacing heads too far apart expecting spray to reach without head-to-head overlap.
- • Plotting trench paths directly across underground utility lines.
Excavate Trenches to Proper Depth
Dig along your painted layout lines using a trenching shovel or powered trencher to a uniform depth of 8 to 12 inches. Slice the top sod into neat slabs using a flat spade and place the sod on a tarp on one side, piling subsoil on a separate tarp on the other side. Clean out loose dirt from the bottom of the trench so the floor sits flat.
- • Clean, flat-bottomed trenches 8 to 12 inches deep across the entire run.
- • Neat rows of cut sod squares and excavated dirt neatly segregated on plastic tarps.
- • Digging trenches shallower than 6 inches, exposing pipes to aerators and surface freezing.
- • Mixing topsoil and subsoil directly on the grass, killing the surrounding lawn.
Assemble and Connect the Valve Manifold
Connect the backflow-protected water supply line to the multi-port valve manifold inside an underground valve box. Thread automatic inline solenoid valves onto the manifold ports using Teflon tape on male threads. Hand-tighten each valve assembly securely, then turn an extra quarter turn with channel locks without cracking the plastic bodies.
- • Level valve box with the lid sitting flush with lawn grade.
- • All solenoid valves aligned parallel inside the box with room around each body for servicing.
- • Over-tightening plastic PVC threads causing hairline splits in the manifold body.
- • Installing valves backward relative to the water flow direction arrow molded on the valve.
Lay Lateral Poly Pipes and Install Tees
Roll out flexible poly pipe into the bottom of the trenches along each dedicated zone circuit. Cut the pipe squarely using an irrigation pipe cutter at each flagged sprinkler location. Slide stainless steel crimp clamps over the pipe ends, insert barbed tee fittings fully to the stops, and crimp the rings tightly in place.
- • Pipe resting flat on the trench floor without kinks, loops, or sharp bends.
- • Barbed fittings fully inserted with crimp clamps seated 1/8-inch from the cut edge.
- • Cutting pipe at an angle, preventing the barbed fitting from seating fully.
- • Leaving crimp clamps loose or positioned too far back on the fitting barbs.
Mount Sprinkler Heads on Swing Pipe
Thread a spiral-barb elbow into the bottom of each pop-up sprinkler body and into the branch tee on the lateral line. Connect them using a 6-to-12-inch length of flexible swing pipe (funny pipe) pushed firmly over the spiral barbs without clamps. Position the sprinkler body vertically against the trench wall so the cap sits exactly 1/2-inch above soil level.
- • Sprinkler body standing perfectly plumb when checked with a torpedo level.
- • Wiper seal cap resting flush with the final grade of the turf soil.
- • Placing sprinkler bodies too high, exposing them to lawnmower blades.
- • Rigidly plumbing heads directly to the lateral pipe without flexible swing pipe.
Flush System Lines and Install Nozzles
Leave flush caps on the sprinkler bodies and turn on the water supply zone by zone to blast out dirt, rocks, and debris from the lines. Allow water to run clear for 30 to 45 seconds per zone, then shut the water off. Remove the flush caps, drop the screen filters into the bodies, and thread on the matched spray nozzles according to your arc patterns.
- • Clear, grit-free water shooting out of every open pop-up body during flush.
- • Nozzles threaded securely onto stems with arc adjustment indicators pointed toward the target lawn area.
- • Installing fine spray nozzles before flushing, instantly clogging nozzle orifices with dirt.
- • Forgetting to insert the small basket filter screen beneath each nozzle.
Wire Controller, Backfill, and Test
Run multi-strand irrigation wire from the valve box to the controller, connecting common (white) wire and individual zone wires using gel-filled waterproof wire nuts. Backfill trenches halfway, tamp the soil firmly with your boots, and run a complete cycle test on the controller. Once verified leak-free, backfill completely, tamp, and replace original sod pieces over the trenches.
- • Waterproof grease caps completely encapsulating twisted wire splices in the valve box.
- • Sod laid flat and level with surrounding turf with no visible trench depressions.
- • Using standard indoor wire nuts inside valve boxes, causing corroded connections within months.
- • Failing to tamp soil during backfill, creating sunken ruts after the first rain.
Credit: inspired by an original tutorial by This Old House — watch the original on YouTube.
Don’t have everything?
- No Walk-behind trencher? Trenching spade and pick mattock
- No Crimp ring tool? Nut driver with stainless steel worm-gear hose clamps
- No Flexible swing pipe? Threaded street elbows with cut Schedule 40 PVC risers