Abstract: In an apparatus for filling bottles with liquid, the liquid supply tank has several bottle filling adapters mounted to its body and providing a valve seat for liquid to flow from the tank to a bottle. The seat is proximate to a vertically movable valve body which has an integral tubular stem extending upwardly from it and a gas tube extending downwardly from it so gas can be conducted downwardly into a bottle and upwardly for being exhausted or returned to the tank. In the bore of the tubular combination gas conducting tube and valve stem there is a wire constituting a filling level probe. The tip of the wire is exposed in the gas tube to liquid in the bottle and the body of the wire is insulated and runs upwardly through the bore of the tubular stem where it is terminated in a cylindrical conductive element that enters an electrical connector. The connector provides a lead to a microprocessor based controller.