A ball-on-pipe water tower is an elevated water tank with a central shaft which flares into a round container at the top. It is constructed for storing water and increasing pressure in a water system.

The central shaft supports the rounded tank without the separate side legs of a multilegged water tower. The tank remains elevated for storage and water-supply pressure.

The rounded upper container and narrower supporting shaft give the structure its recognizable form. Its appearance describes the support arrangement, separately from the quantity of stored water.