ABSTRACT
A candidate for the type of castellum is to be found at the terminus of the Claudia and Anio Novus aqueducts where remains suggest a five chambers that divide aqueduct flow to separate destinations with different water flow rate requirements. A further candidate castellum of the type is provided by the water distribution system at Ephesus where an unexcavated site exhibiting pipelines to different destinations with different water needs strongly suggests a castellum of this type. Typical designs indicate a pipeline constriction insertion device designed to measure flow rate; markings on the calyx indicate the value of the flow rate in quinaria that the calyx allows through its orifice. As part of Roman water distribution networks, water from aqueducts was delivered to reservoir basins then to castellum systems which, for public use, contained calyx devices to measure flow rate with a tax appropriate to that flow rate.
