Abstract: In a siphon for lavatory basins and the like, of the kind comprising a main body having an upper inlet opening, a lateral outlet opening and an open lower end closed by a removable socket, the socket is disposed obliquely at an acute angle to the vertical axis of the main body and the inner tube, which is connected to the outlet fitting of the basin, has a lower portion which extends obliquely through the lower end of the main body and into the removable socket, substantially co-axially thereto.