Per-zone flow: heads × nozzle
| Nozzle type | Flow per head | Typical heads/zone | Zone flow |
|---|---|---|---|
| Fixed spray | 1.5-3 GPM | 4-6 | 8-12 GPM |
| MP rotator | 0.5-1 GPM | 8-12 | 6-10 GPM |
| Gear-drive rotor | 2-5 GPM | 4-6 | 10-20 GPM |
| Drip line / emitters | 0.5-1 GPH per emitter | 100-300 | 1-5 GPM |
So a typical residential zone draws 6-12 GPM while running - that is the number your supply must cover at once, with a 10-30% margin on top.
Whole-system flow: zones run sequentially
The system total is not heads × GPM for the whole yard - zones take turns. A 6-zone spray system with 10 GPM zones still only needs a 10-12 GPM supply; it just runs the zones back to back. What multiplies is time: six zones × 15 minutes ≈ 90 minutes to water everything once.
What your supply can realistically run
- 8-12 GPM (typical residential outdoor tap): spray zones of 3-5 heads, MP zones of 10+, or drip zones of several hundred emitters.
- 15-25 GPM (1-inch meter, larger service): bigger rotor zones and shorter total schedules.
Measure yours with the bucket test, then total a planned zone with the Irrigation Flow Calculator and check it against the supply with the Sprinkler Zone Calculator - it flags when the flow does not fit.
If the answer is "more than you have"
Switch to lower-flow nozzles (MP rotators), shrink zone sizes, or ask a plumber about upsizing the service line. Do not plan zones at 100% of measured flow - the far head will always tell you about it in August.