Drip Irrigation Design Guide: Pump & Flow Calculation

How do I calculate the water requirement of a crop?

Water Requirement = Crop Area * Evapotranspiration Rate * Crop Coefficient. A typical vegetable plant needs 2 to 4 liters of water daily.

What is the standard flow rate of a drip emitter?

Standard emitters deliver 2 liters per hour (LPH) or 4 LPH of water directly to the root zone at a pressure of 1 bar.

What is pressure compensation (PC) in drippers?

PC drippers maintain a constant water flow rate even if the land is sloping or pressure drops along the lateral pipe line.

How do I choose the correct pump HP for drip irrigation?

Calculate the total discharge needed (number of emitters * LPH) and the total head (vertical height + friction loss in pipes) to select pump HP.

What is head loss in irrigation pipes?

The drop in water pressure caused by friction between the flowing water and the inner walls of the plastic pipes.

Why is a sand filter necessary?

If you draw water from a canal or open pond, a sand/media filter is mandatory to remove mud, algae, and organic debris before it blocks drippers.

What is the ideal lateral line length?

For 16mm lateral pipes, keep the line length under 100 meters to ensure uniform water pressure from start to end.

How do I perform a system flush?

Open the end caps of all lateral lines and run the pump for 5 minutes to wash out any settled mud or mineral scale.

What is sub-surface drip irrigation?

Burying drip lines 6 to 10 inches below the soil, which cuts evaporation, stops weed growth, and protects lines from rodent bites.

Can I run drip irrigation on gravity pressure?

Yes, for home gardens or small patches, placing a water tank 5 to 10 feet high provides sufficient gravity head pressure for low-pressure drippers.

A Guide to Drip Irrigation Design and Calculation for Small Farms