1Your property
Start with the essentials. You can fine-tune the assumptions below.
Compare your best options
See two smaller choices, our recommendation, and two larger options.
Behind the result
A better estimate than litres × dry days.
Storage matters, but so do refill timing and roof yield. The calculator models how water moves through the tank day by day.
- Find your location and retrieve up to ten full years of historical daily rainfall.
- Turn rainfall on your selected roof area into harvestable litres.
- Simulate daily inflow, demand, overflow and shortfall for every available tank size.
- Recommend the smallest stocked tank that meets your chosen dry buffer and supply target.
Important: Historical rainfall is not a forecast or guarantee. This is a planning estimate, not an engineering, plumbing or site assessment. Call 02 6624 4662 for property-specific advice.