The site uses public-sector health, plumbing, stormwater and environmental guidance as a starting point, then keeps local decisions with the responsible authority.
Core reference set
- US Centers for Disease Control and Prevention — Collecting Rainwater and Your Health
- US Environmental Protection Agency — Rainwater Harvesting Practices
- US Environmental Protection Agency — National Stormwater Calculator
- National Research Council Canada — National Plumbing Code of Canada 2020
- British Columbia Ministry of Health — Guidance for Treatment of Rainwater Harvested for Potable Use
- Australian Department of Health and Aged Care — Guidance on the Use of Rainwater Tanks
- NSW Health — Rainwater Tanks
- UK Government — National Standards for Sustainable Drainage Systems
- UK Environment Agency — Rainwater Harvesting Regulatory Position Statement
- Ontario — City of Waterloo Rainwater Harvesting System case study
Calculator methods
The capture calculator uses the standard roof-area × rainfall-depth × runoff-factor relationship. The tank tool is a simple dry-period demand screen, not a rainfall time-series model. The overflow tool compares event inflow with free storage. The payback tool uses net initial cost divided by annual water value after entered maintenance.
Currency and prices
The site does not publish fixed universal prices. Visitors enter local costs, tariffs and incentives because labour, excavation, permits, equipment and water pricing change by place and time.
Review boundaries
Official sources can be revised and model codes may not be adopted in a particular jurisdiction. Always verify the current local edition and requirements before relying on a technical detail.
Last editorial review: August 5, 2026.