How big your rainwater harvesting system should be
Domestic water use
A tank volume of approximately 1,000 liters is required per person for domestic water use.
For every 150 m2 of intensive irrigation area, a tank volume of approx. 1,000 liters is assumed.
To determine the required roof surface: for every 1,000 liters of tank volume, approx. 20-25 m2 of roof surface should be available.
Mr. Practical would like to purchase a simple rainwater harvesting system for garden irrigation at the lowest possible financial cost. His property area is 600 m², of which the house occupies 100 m².
The roof surface is suitable to fill a tank of 4,000 litres. The system is a budget option and the extensive garden irrigation requires a tank of this size.