A farmer has a 10 ha field that requires 5 mm of water per day for 30 consecutive days. The irrigation system used has an efficiency of 70 %. How many litres of water must the farmer supply in total?

Step-by-step solution

1. 1) Convert area from hectares to square metres: 10 ha = 10 × 10,000 = 100,000 m².
2. 2) Convert depth from millimetres to metres: 5 mm = 0.005 m.
3. 3) Compute daily volume of water needed: 100,000 m² × 0.005 m = 500 m³.
4. 4) Multiply by 30 days: 500 m³ × 30 = 15,000 m³ for the period.
5. 5) Convert cubic metres to litres: 15,000 m³ × 1,000 = 15,000,000 litres.
6. 6) Adjust for system efficiency (70 % = 0.70): 15,000,000 ÷ 0.70 = 21,428,571 litres.
7. 7) This is the total volume the farmer must supply.

Concept tested: Irrigation water requirement calculation

Published 10 October 2026 · How this solution was prepared and checked