Rainwater Harvesting API
Rainwater-harvesting maths as an API, computed locally and deterministically. The harvest endpoint works out how much water a roof collects from a given rainfall — from the catchment (roof plan) area, the rainfall depth and a runoff coefficient it returns the harvested volume in litres, US and UK gallons and cubic metres, using the identity that 1 mm of rain over 1 m² collects 1 litre before losses. The runoff coefficient can be given directly or looked up from the roof type (smooth metal collects the most at ~0.9, green roofs the least at ~0.3). The demand endpoint sizes a storage tank from a daily demand (given directly or as people × litres per person) and the length of the dry spell you want to cover, and — if you also pass the annual rainfall and roof area — checks whether a year of harvest can meet a year of demand. The firstflush endpoint sizes a first-flush diverter, the volume of dirty initial rain to discard. Areas accept square metres or square feet (or length × width), rainfall accepts millimetres, centimetres or inches. Everything is computed locally and deterministically, so it is instant and private. Ideal for sustainability and off-grid apps, plumbing and landscaping tools, smart-home water systems, and construction planners. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is rainwater catchment maths; for roof pitch and area geometry use a roofing API and for general construction material quantities use a construction API.
api.oanor.com/rainwater-api
