RAINWATER TREATMENT DEVICE

The disclosure relates to a rainwater treatment device comprising a fluid inlet (11), a fluid outlet (12), a cartridge accommodation space (20) for removably receiving a cartridge including a substrate for treating rainwater, a fluid receiving space (50) for receiving fluid flowing out of the accommodation space (20), the fluid receiving space (50) being fluidly connected to the fluid outlet (12) by a drainage flow path, and an overflow damming element (40) provided in the drainage flow path and/or the fluid receiving space (50) for damming up fluid in the fluid receiving space (50) and the accommodation space (20) and for reducing a fluid throughput in the drainage flow path towards the fluid outlet (12) for as long as the overflow damming element (40) does not overflow.