Abstract: A filter cartridge has a pleated filter media rolled into a cylinder, a tubular core, moulded from plastic with alternate grooves and ridges provided at the outer surface and a collar with uniformly spaced teeth which envelopes the filter media to rigidly space the pleats. The collar is retained by friction and it may be displaced towards the end caps of the cartridge. The core may be withdrawn from the filter media of a waste cartridge and utilized in a new cartridge. The upper end cap has a handle with a hinge provided by a reduced section of the plastic material.