Grit separating apparatus comprises an annular settling chamber having a floor which slopes conically downwards to an annular grit collecting channel. A conduit for removing grit extends downwardly through the chamber into the channel and is moved lengthwise of the channel to remove grit therefrom. The conduit is conveniently mounted on a bridge extending radially over the annular chamber and the bridge may serve to support agitating means to move the water through the setting chamber at an effective flow velocity between a raw water inlet port and a treated water outlet port.