A filling apparatus for serially filling multiple lanes of containers includes a plurality of piston pumps which receive flowable product from an associated source. Each pump includes a reciprocably movable pump piston, which can “float” upwardly during a filling stroke, as each pump is filled with product delivered thereto under pressure. The pump pistons can move upwardly independently, until each reaches a predetermined position, corresponding to the quantity of product with which each container is to be filled. After all of the pistons reach their respective predetermined positions, valves of the pumps are simultaneously operated, and the pistons simultaneously stroked so that respective containers are filled with the flowable product. The multiple lanes of containers are thereafter indexed, and the filling cycle repeated.