Abstract: A liquid dispenser having a liquid flow duct through which liquid may flow from a liquid source into a battery or the like. The dispenser includes a light-transmitting portion adjacent the flow duct to produce a visual indication of the surface elevation of a pool of liquid into which the liquid flows. Available light at the outer end of the light-transmitting portion passes in and through the latter to a reflective, inner end of the light-transmitting portion and is then reflected back out to provide a visual indication that the reflective end is not immersed in the pool of liquid. When the level of the pool has risen to immerse the reflective end, the available light reaching the reflective end is refracted into the liquid, and immersion is indicated by the relative absence of reflection.