Galleria Bassa and Fonte Carolina are the two springs located at about 600 meters above sea level, at the foot of the village of Santa Fiora. They are located near the water purification plant, completed in 1982 and derive water from two separate water capture works that are about 45 meters away from each other.
Downstream of the village of Santa Fiora, two springs flow: Galleria Bassa and Fonte Carolina. They are located at about 620 meters above sea level and in the historical documentation they are considered as part of a single source of supply called Fonti Mannarine. They are located downstream of the town of Santa Fiora, near the water purification plant and derive water from two separate water capture works. The excavation of the Fonte Carolina tunnel dates back to 1913 and is 17 meters long, with the water coming out at the bottom of the tunnel from a spring in the trachyte mass. The tunnel has a barrel vault made of concrete and plastered. The captured water is collected in a semicircular channel that flows into three settling tanks, the last of which leads the resource into a collector. The Galleria Spring is much larger in size, characterized by a tunnel of about 70 meters in length with water coming out of three main springs. The vault and the walls are made of settled and tightened trachyte blocks. The water coming from the springs is channelled into a steel pipe and under this pipe, next to the pavement, there is a channel, able to collect the water on the occasion of temporary shutdowns of the steel pipe. Since 1982 the waters of Galleria Bassa and Fonte Carolina springs have been distributed undergoing therefore a purification treatment. Initially the water purifier included a lifting unit, an ozone oxidation stage and a battery of activated carbon filters. Currently, the waters captured by the two springs are subjected to pre-treatment of sedimentation / de-sanding, pre-oxidation, filtration on quartz sand and final disinfection with sodium hypochlorite.