What is a first flush diverter?
This is an absolutley necessary part of a roofwater harvesting system and will keep concentrated toxic chemicals out of the slow sand filter. A first flush diverter (sometimes called a “roof washer”) is a device that manages the flow of rainwater into a harvesting system. It diverts the first flow of runoff from a roof, after a dry spell, away from a roof water harvesting system. There are many different designs, but the idea is the same – prevent water that contains dissolved pollutants such as: dust, vehicle exaust particles, animal droppings, and particulate matter due to poor air quality from entering the water storage system. The runoff from the first rain after several months of a dry spell will contain concentrated highly toxic materials including harmful bacteria. A diverter usually has a “temporary storage chamber” that fills with the most polluted water and then seals itself off to allow the fresh rainwater to flow into the storage system while slowly emptying this “temporary
