Abstract: A system for controlling a flow of water out of a container in a manner to prevent the generation of noise as an incident to the outflow and to permit adjustment of the water level in the container, the container being a component of apparatus for maintaining water at a desired level in an enclosure. The system basically includes: an outflow conduit defining an outlet flow path via which water flows downwardly out of the container, the conduit having an upper end located within the container and having an inlet opening; a cap overlying the inlet opening and defining with the conduit upper end an annular flow path via which water flows to the inlet opening; and a vent tube extending vertically downwardly through the cap and into the conduit to establish an air flow path between a region above water in the container and a region within the conduit.