PangPang ToolsRainwater Harvest Estimator: Accounting for rainwater runoff losses — Worked Scenario
How do you check accounting for rainwater runoff losses without overlooking a default value or an assumption? Follow the input and result from Rainwater Harvest Estimator, then review what can change the output before using it.
Tool walkthrough based on an illustrative example; this page is still awaiting an independent content review. Do not treat it as official guidance or a verified regulatory result.
Check the worked example in Rainwater Harvest Estimator
What this scenario actually checks
One millimeter of rainfall across one square meter is one liter of water before losses. Apply the runoff factor and separately allow for first-flush and storage overflow. Rainwater Harvest Estimator performs a browser-local calculation using measurements and quantities you control. The results are presented as labelled figures so each number is easy to interpret. Excludes first-flush, storage overflow, contamination and timing of rainfall.
This walkthrough focuses on accounting for rainwater runoff losses. It follows the published tool inputs, not a new formula or an automatically verified legal, financial, medical or engineering determination.
Start by preparing the right inputs
Enter the following fields using their displayed units: Catchment area (m²), Rainfall (mm), Runoff coefficient. Press Calculate to display the geometric or theoretical results. Excludes first-flush, storage overflow, contamination and timing of rainfall.
Before copying the example, confirm that each entered unit, date, dimension and default matches your real task. Changing only a visible number without revisiting its assumptions can change what the answer means.
- Enter the following fields using their displayed units: Catchment area (m²), Rainfall (mm), Runoff coefficient.
- Press Calculate to display the geometric or theoretical results. Excludes first-flush, storage overflow, contamination and timing of rainfall.
- Review material specifications, design constraints and required safety checks separately before procurement or installation.
Worked example with the calculator
Use the following input values: Catchment area (m²): 100, Rainfall (mm): 20, Runoff coefficient: 0.85.
The example output is Rainfall volume: 2,000 L. Using these sample input values gives the first labelled output above. Excludes first-flush, storage overflow, contamination and timing of rainfall.
Treat this as a reproducible example, not a result to reuse with different measurements.
What can change the answer
Review material specifications, design constraints and required safety checks separately before procurement or installation.
Can I use the default numbers for purchasing or safety certification? No. Replace the examples with your real values. Excludes first-flush, storage overflow, contamination and timing of rainfall.
Is the calculated rainwater volume safe to drink? No. The tool estimates quantity only; collection-system treatment, roof contamination and water quality are not assessed.
Before using the result for a real decision
For accounting for rainwater runoff losses, check the original measurements and input units, and save the assumptions alongside any number you share.
Where legal rules, official allowances, equipment ratings or contractual conditions matter, consult their current authoritative documents. An illustrative estimate is not a substitute for that verification.
- Reproduce the example before changing inputs
- Check all units and assumptions, including any default values
- Verify official or manufacturer-specific requirements outside the calculator
Related tools
Use the tools to verify the steps against your own files or text.