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Rainwater Harvesting Calculator

Calculate annual rainfall collection and tank sizing for Australian homes using BOM state averages.

AU Rainfall DataTank Sizing

Roof Catchment Area (m²)

State

Tank Size (litres)

Daily Household Use (litres)

About this tool

Calculate annual rainfall collection and tank sizing for Australian homes using BOM state averages. This tool gives a general estimate based on standard assumptions — actual results will vary depending on your specific site, equipment and conditions.

How to use it

Enter your property or system details into the fields.
Adjust the inputs to match your location and setup.
Calculate to see your estimated result.
Try different figures to plan for different scenarios or upgrades.

Common use cases

Planning a new install or system before committing to it.
Estimating running costs or yield before you invest.
Comparing a couple of setup sizes or configurations.
Getting a rough figure to take to a supplier or installer.

About this calculator

Calculate annual rainwater collection and recommended tank size for Australian homes using BOM state rainfall data. The Rainwater Calculator page explains what the tool or support page provides, what information is needed and how to use the result or guidance for an everyday task.

Use Rainwater Harvesting Calculator when you need a quick answer without creating an account, downloading an app or sending your information to a third party. The tool is designed for everyday planning, comparison and checking, with results shown in the browser as soon as you enter the details.

How to use Rainwater Harvesting Calculator

Enter the dates, numbers or options requested by the form on this page.

Choose any unit, country, time period or setting that applies to your situation.

Press the calculate or generate button to show the result.

Review the explanation beside the result before relying on it for planning.

When this page is useful

Rainwater Harvesting Calculator is useful for quick checks, household planning, school or work tasks, content planning and comparing simple scenarios. Many visitors use these tools to avoid manual counting or spreadsheet setup for a one-off question.

The result should be treated as a practical guide rather than professional advice. For legal, financial, health, tax, pregnancy, school holiday, tide or public holiday decisions, confirm important details with an official source or qualified professional.

Privacy and accuracy

MyCalcTools tools run in your browser wherever possible. We aim to keep pages clear, lightweight and easy to read on mobile, tablet and desktop. If a page uses dates, public holidays or calendar rules, those rules can change over time, so checking the final result against the relevant authority is recommended for high-stakes decisions.