Long-Run Sprinkler Supply Line: Pressure Loss and Pump Sizing

One-mile supply line: 1.5" PVC reduced to 3/4" for 500 ft, then 1" main to 1/2" laterals. 55 PSI, 0.183 GPM (very low). 6 valves, 36 heads (6/valve).

Critical Issues

• Volume (GPM) is key: 0.183 GPM is < 1/5 gallon/minute—far below sprinkler needs (0.5–4 GPM/head).
• Pipe sizing: Larger pipe reduces friction loss. Run 1.5" all the way to house.
• Test flow at 1.5" end: Cut, add elbow, run 1 minute, read meter. If ≥10 GPM, continue 1.5" to house. If ≤8 GPM, need booster pump.
• Lateral size: 1/2" limits to ~5–7 GPM regardless of pump.

Match pump to total zone GPM (typically 12–20 GPM/zone at 60–80 PSI).