Placed directly under a Rain Head, a First Flush diverter prevents the highly polluted water from entering the tank. An automatic ball and seat system directs this water to a diversion chamber. Once the chamber is full the ball seals the chamber and directs water to your downpipes and onward to your tank. A slow release valve empties the chamber after rain and the system is ready to divert the first flush of polluted water next time it rains.

The quantity of first flush water that needs to be diverted depends on the area of roof from which water is harvested and the severity of pollutants on the roof.

For a roof with minimal pollutants - clean environment, no trees, no bird or animal droppings divert ½ litre per square metre of roof.

For a roof with substantial pollutants - large amounts of leaves and debris, bird or animal droppings, dead insects etc divert 2 litres per square metre of roof.

Fitting an appropriate sized diversion chamber is critical to harvest good quality water.

Post or wall mount kits are available for 300mm pipe to allow simple installation.

If several downpipes merge to one pipe entering the tank a (larger) single unit may be used. Maintenance of one unit may be easier than diverters at each downpipe.