Water Usage Calculator
Enter the number of people and adjust the litres per person per day for each activity to match your household.
Your result will appear here after you press Calculate.
How this calculator works
Daily use = people × Σ(litres per person per day for each activity) + extra daily use
Monthly = daily × 30; Yearly = daily × 365
Storage needed = daily use × days of storage
Assumptions and limits
- The litres-per-person values pre-filled in the table are sample assumptions for illustration, not official norms. Edit them to reflect your household.
- Seasonal changes and leaks are not included.
This tool gives an approximate estimate from the values you enter. It is not a substitute for professional engineering design, site inspection, official quotations or applicable building regulations. See the calculator disclaimer.