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Rainwater harvesting: the cheapest tank you will ever install
A 100 m² roof in a 600 mm/year climate yields roughly 48 m³ of usable water. Filtration, first-flush diverters and tank sizing decide whether it stays drinkable.
≈48 m³/year per 100 m² roof
A 100 m² roof in a 600 mm/year climate yields roughly 48 m³ of usable water. Filtration, first-flush diverters and tank sizing decide whether it stays drinkable.
Size the tank for the dry spell, not the annual total: 30 days of demand is the usual rule. A first-flush diverter of 0.5 l/m² of roof removes most of the dust and bird load, and a dark, sealed tank keeps algae out without chemicals. Potable use needs filtration plus UV, and in most jurisdictions a backflow-protected separation from the mains.
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