A device for separating debris and other material from rainwater as it flows into a downpipe from a roof gutter is disclosed. The device has a compartment for fitting to the upper end of a downpipe. The compartment has a horizontally pivoted perforated drum which rotates when rainwater and entrained debris from an overhead gutter impinges on it such that the rainwater passes through the perforations in the drum into the associated downpipe and the debris is ejected outside of the device by the rotation of the drum.