Abstract: An oil skimmer in combination with a channel that directs the flow of waste water from surface drainage, or the like. There is a weir at the downstream end of the channel to maintain the level of the waste water in the channel. A pivotally supported tray goes across the channel and is mounted so that it has a normal attitude parallel to and beneath the surface of the channel water. This tray has an open end on the upstream side, and there is a means for periodically tipping it so as to wash any floating oil and debris back to the opposite end of the tray where it may be removed.