A container washing and filling machine for washing and filling blow moulded containers 1 having an open-ended neck 2 includes only a single head 5 through which both washing and filling liquid is introduced into the container 1 through its open-ended neck 2. The container 1 is held in fluid-tight sealing engagement with the single head 5 by a clamping device 32 and the clamping device and single head 5 are movable together with a container 1 being treated between a washing position in which the container 1 is inverted and a filling position in which the container 1 is erect. Preferably the machine also inlcudes a closure unit 21 to apply a closure to the open-ended neck 2 of a filled container 1.