RAINWATER TREATMENT DEVICE

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