The baths at Pollena Trocchia were built at the end of the 1st century AD and unlike the urban baths, this establishment had to rely on large cisterns collecting rainwater or diverting a stream. For use in the baths, the water had to be lifted from the underground cistern to a reservoir on the 1st floor.
I reconstruct the lifting device, based on layout of the room with the puteal and cuts in the floor, as a treadwheel powered bucket chain. Calculations show possible discharge of 0,46 l./s., comparable to the Stabian baths.