How the Sprinkler Designer Works

We compute available flow (GPM) from your meter size, pipe diameter, pipe material, and service line length. Friction losses follow standard irrigation hydraulics (Hazen-Williams equation), so longer runs of small-diameter pipe yield lower available flow. We also estimate the dynamic pressure that will actually arrive at the heads — usually 5–15 PSI below your static reading.

Based on the narrowest dimension of your yard, we pick a head type:

• Under 10 ft of throw: 8-Series Rain Bird spray nozzles.
• 10–18 ft: 15-Series or 12-Series sprays, or Hunter MP1000 rotators.
• 18–25 ft: Hunter MP3000 rotators (efficient, low-pressure friendly).
• 25+ ft: Rain Bird 5000 rotors.

If your dynamic pressure is below 30 PSI, we steer toward MP rotators instead of fixed sprays — they perform better at low pressure and waste less water to misting.

The placement runs in three passes:

• Corner heads sit at every vertex of your yard polygon. Their arc snaps to the actual interior angle of that corner (90° for a square corner, 120° for a hexagonal one).
• Edge heads fill long edges between corners, evenly spaced at ~75% of the head's radius for "head-to-head" coverage.
• Interior heads tile the rest of the polygon with 360° heads on a grid sized to overlap each previous head.

Every candidate position is checked against the polygon (must be inside) and against obstacles (must be at least a head's radius buffer away from house/driveway/etc).

One zone = one valve, runs all its heads simultaneously. The sum of head GPMs in a zone must stay under your available flow. The grouper:

• Splits by head type first — never mixes sprays with rotors (their precip rates differ, you'd over- or under-water).
• Clusters spatially using nearest-neighbor inside each type, respecting the GPM cap.
• Merges tiny clusters into neighbors (with a 10% over-cap tolerance) to avoid orphan one-head zones.
• Rebalances oversized or undersized zones so each zone has 3–8 heads where possible.

After zoning, we run a nozzle optimizer: for each zone, can we swap to higher-flow nozzles without exceeding the GPM cap? More flow = shorter run times = less wasted electricity on the controller and less evaporation per session.

A simple TSP-style router connects each zone's heads via a manifold near your water source. The parts list rolls up heads, valves, valve box, controller, PVC pipe, swing joints, and fittings with rough Home Depot prices and Amazon affiliate search links.

Per zone: weekly water target (turf = 1.5 in/week in summer) divided across runs constrained by your soil's infiltration rate. Clay soil gets more frequent shorter runs (the soak-in limit); sand gets fewer longer runs. Run times are computed from each zone's average precipitation rate.

What the engine is NOT

• An engineered plan a licensed irrigator would stamp. It's a homeowner-grade starting point.
• An accounting of local codes, backflow requirements, or permit needs.
• A drip irrigation designer — sprays/rotors only.
• Aware of slopes, microclimates, or special vegetation needs (we use one soil + one veg type per yard).

For most suburban yards under ~10,000 sq ft, the output is good enough to source parts, dig trenches, and have something working. Tweak heads and run times by feel over the first few weeks — that's how a pro does it too.