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Water Usage & Tank Size Calculator

    Total roof area feeding the tank.
    Tip: You can measure your roof area using Google Earth’s Path and Polygon tools .
    How many days you want the tank to cover if it doesn’t rain.
    Inside water use
    Outside water use
    Tip: choose from the dropdown if it appears; otherwise just type and click Calculate.

    How the NRRTanks Water Tank Chooser works

    The NRRTanks Water Tank Chooser provides a practical starting point for selecting a rainwater tank for an Australian home, farm or business.

    What the calculator uses

    How to use your result

    The calculator estimates daily water use, yearly harvestable roof water and the minimum tank capacity needed for your selected no-rain period. It then shows tanks that meet or exceed that capacity. Use the result as a guide, then consider site access, available space, plumbing requirements and your intended water use before ordering.

    Important: This calculator provides a planning estimate using the information entered and long-term rainfall data. It is not a site inspection, engineering assessment or guarantee of water supply. Contact NRRTanks for advice tailored to your property.