The cistern is a circular space with an internal radius of 4.5’ and height of 7’. The walls are made of 27” rammed earth tires in a running bond pattern with an internal 8” concrete layer to provide a waterproof barrier.

The use of a circular shape creates a geometrically stable shape where no buttressing is needed. In addition, it allows to avoid the presence of sharp corners where stresses would accumulate in case of earthquakes, thus creating weak spots in the structure.