(2 different types with the same functioning principle). The device is needed for intermitted loading of the first filter stage: a chamber of several m3 is slowly filled by wastewater influent, once the chamber is full it is emtpied with a high flow onto the surface of the filters. The system works with a floating device that carries big pipes connected to the outlet with a flexible pipe section. When the chamber is almost full, the floating device is stopped, gets submerged, sinks to the bottom and water is siphoned through the pipes towards the filters until the chamber is empty. If not enough slope for gravity flow is available, a pump with high flow can replace the siphon device.