Commercial Drip System Pressure Loss: 2" Mainline Too Small for 1500' Run

Commercial project: 35 PSI city supply, 2" meter, 1500' of 2" PVC mainline, 2" RP backflow preventer, all drip + 6 quick couplers. Pressure at end is near zero.

Pressure Loss Calculation

• 2" meter: 2 PSI loss at 51 GPM max safe flow
• RP backflow preventer: 8-12 PSI loss (use 12 PSI)
• 1500' of 2" PVC at 51 GPM: 1.99 PSI/100' = 29.85 PSI loss
• TOTAL LOSS: 43.85 PSI

Result

System cannot work. 35 PSI supply - 43.85 PSI loss = negative pressure.

Required Fixes

1. Multiple zones: Reduce simultaneous flow to 15-20 GPM max
2. Larger mainline: 3" PVC cuts friction loss ~60%
3. Booster pump: Add if pressure insufficient after zoning

Resource

Drip design guide: irrigationtutorials.com. Hire irrigation designer for commercial projects.