For certain applications, Preload’s prestressed concrete tanks are constructed with an open top. Like our dome or flat-roof tanks, Preload’s open-top tanks consist of a circular cast-in-place, reinforced concrete, floor slab and a precast, circumferentially prestressed, concrete wall incorporating a continuous mechanically bonded steel diaphragm. Preload’s open top tanks are also subject to the requirements of the ANSI/AWWA D110 Standard for Wire- and Strand-Wound Circular Prestressed Concrete Water Tanks - Type III: Precast Concrete With A Steel Diaphragm.