Drip Irrigation System Calculator – Zones

System design starts at the emitter. Multiply emitters per zone by the emitter discharge to get zone flow, then check it against the 20–30% pressure-limited supply. Worked example: 1 ha of tomatoes, paired rows 1.5 m apart → 6,667 lateral-m with 30 cm (0.3 m) emitter spacing ≈ 22,222 emitters; at 2 L/h each, zone flow = 22,222 × 2 = 44,444 L/h ≈ 195 GPM — too much for one valve, so split into 2 zones of ~22,000 L/h (97 GPM) each on a 63 mm submain. Applying 6 mm per event with emitters wetting the full strip (application rate ≈ 4 mm/h) takes 1.5 hours per zone. Daily ETc of 6 mm ÷ 90% emission uniformity sets the schedule.

1. 1

   Step 1

   Enter area, row and emitter spacing to count emitters.

2. 2

   Step 2

   Choose emitter discharge (1–4 L/h).

3. 3

   Step 3

   Read zone flow in L/h and GPM; adjust the number of zones.

4. 4

   Step 4

   Enter target mm per event to get run time in hours.

• 1

  Keep zone flow within 70% of the pump’s rated flow

• 2

  Filter to 120–150 mesh for drip tape

• 3

  Pressure-compensating emitters above 2% slopes

• 4

  Flush laterals every 2–4 weeks in hard water

• Running more zones than the pump can hold pressure for

• Ignoring emission uniformity — design to 85–95%, not 100%

• Mixing 2 L/h and 4 L/h emitters in one zone

• Forgetting flush points so laterals clog at the ends