WaterCalcLabRainwater Savings Calculator
Bound potential mains replacement by both available rainwater and eligible demand in the same period.
Your result
Bars compare only results in the same unit group. They are normalized, not a time-series forecast.
Planning result based on your inputs.
How this tool works
Bound potential mains replacement by both available rainwater and eligible demand in the same period.
replacement = min(supply, demand); saving = replacement/1000 × priceExample calculation
The prefilled form is a worked example. Its base-unit inputs and expected outputs are shown below; use the reset button to restore it.
| Input | Example |
|---|---|
| Available supply in the same period | 15000 |
| Demand in the same period | 20000 |
| Avoidable volumetric price | 3 |
Frequently asked questions
How should I choose the inputs?
Use measurements and local records for the stated period. All preset values are illustrative examples, not recommendations.
What does this result leave out?
This upper bound ignores seasonal mismatch and overflow. Enter realized usable supply where possible. Fixed charges and non-avoidable sewer charges remain.
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Method version 1.0 · Last reviewed: 2026-10-10