How do I size a rainwater tank?

Tank volume should cover 2-3 months of demand minus rainfall supply during driest period. Model monthly supply vs demand to find peak storage deficit.

What roof area is needed for significant water savings?

A 100 sqm roof in a 500mm annual rainfall region collects ~45,000 liters/year (at 90% efficiency), enough for basic household use in many climates.

Rainwater Tank Sizing by Catchment Area Calculator

Formula Definitions

The Rainwater Tank Sizing by Catchment Area Calculator works by applying a well-defined formula to the values you enter. Understanding the formula behind the calculation helps you interpret the result and check that your inputs are correct. Below we break down the key components that drive the Rainwater Tank Sizing.

The core formula used by this calculator is:

Result = f(inputs, settings)

Each variable in the formula has a specific meaning:

inputs — Values entered into the Rainwater Tank Sizing.
settings — Options, units, or parameters that adjust how the calculation is performed.
Result — Computed output for the chosen inputs and settings.

How to Use This Calculator

Enter the required values. Enter the required values into the Rainwater Tank Sizing by Catchment Area Calculator input fields.
Adjust settings. Adjust any settings, select applicable options, or choose units as needed.
Calculate the result. Press Calculate to compute the result using the underlying formula.
Interpret the output. Review and interpret your result using the provided context, reference ranges, or explanatory notes.

Glossary and Definitions

Input: A value entered into the calculator to be processed.
Output: The computed result returned by the calculator for the given inputs.
Setting: An option that adjusts how the calculation is performed, such as unit selection or mode.
Rainwater tank sizing: A key concept referenced by the Rainwater Tank Sizing: Calculate the optimal rainwater harvesting tank size based on roof catchment area, local rainfall patterns, and household water demand. Model dry season shortfall risk and optimal tank volume for different self-sufficiency targets.
Rainwater harvesting calculation: A key concept referenced by the Rainwater Tank Sizing: Calculate the optimal rainwater harvesting tank size based on roof catchment area, local rainfall patterns, and household water demand. Model dry season shortfall risk and optimal tank volume for different self-sufficiency targets.
Tank volume calculator: A key concept referenced by the Rainwater Tank Sizing: Calculate the optimal rainwater harvesting tank size based on roof catchment area, local rainfall patterns, and household water demand. Model dry season shortfall risk and optimal tank volume for different self-sufficiency targets.
Water collection tank size: A key concept referenced by the Rainwater Tank Sizing: Calculate the optimal rainwater harvesting tank size based on roof catchment area, local rainfall patterns, and household water demand. Model dry season shortfall risk and optimal tank volume for different self-sufficiency targets.

Related Calculators

Earthship Water Sizing

Miscellaneous Niche

Off-Grid Solar Sizing