First flush diverters are devices used in stormwater harvesting systems to divert the initial flow of runoff away from the storage area. When rain begins to fall, the first portion of runoff typically contains the highest concentration of contaminants such as dust, leaves, bird droppings, and other pollutants that have accumulated on rooftops or paved surfaces. The first flush diverter captures and isolates this initial runoff, preventing it from entering the storage tank or reservoir.
Once the first portion has been diverted and the rain continues, cleaner water is then allowed to flow into the storage system for reuse. These devices often use simple mechanisms such as valves, chambers, or floating balls to control the flow. By removing the most polluted water at the start of a rain event, a first flush diverter helps protect the quality of the stored stormwater and reduces the need for more extensive treatment later on.
