The History of the Aqueduct Supplying the Fonte Gaia
It was under the Rule of the Nine (from the end of the thirteenth century through the first half of the fourteenth century) that Siena changed its appearance: the grey stone was replaced by the distinguishing hues of red brick. There was the construction of the Palazzo Pubblico, of the Torre del Mangia, and the re-design of the Campo; the main streets were paved with stone or brick; one saw the enlargement of the walls and the attempt to build the largest cathedral in Christendom.
In 1334 Jacopo di Vanni was entrusted with bringing water from sources north of the city, and this water arrived in the Piazza del Campo, the center of civic life, in 1343. In 1343 the bottino reached Fontebecci and a means of linking it with the water of the river Staggia near Quercegrossa was sought.
In 1387 the branch of Uopini was completed and an attempt to direct the water of Mazzafonda into the bottino of Fontebranda was made.
In 1437 they worked on the Marciano branch.
In 1438 the "galazzoni" were built under the field of Camollia. The galazzoni were a series of settling tanks into which water, flowing very slowly, was clarified and freed from impurities and where excessive calcites could precipitate.
In 1466, in addition to continuing the search for other veins of water, the network of aqueducts had reached their greatest extent, with a total of 25 kilometers of tunnels. After this date the work consisted only of maintenance and consolidation.
For the entire period extending from the surrender of Siena in 1555 until after the first World War, when the Vivo Aqueduct was put into service, Siena continued to use the bottini as the sole source of water supply for all the purposes that have been previously enumerated.
This was possible thanks to the low number of inhabitants (never more than 20,000) to which Siena was reduced after the plague of 1348. The political tranquility and continuity resulting from the inclusion of Siena into the Grand Duchy of Tuscany permitted the bottini to be tended with greater care, at least with regard to their maintenance, and thus they remain preserved to this day. They were modified in the nineteenth century when many private citizens demanded to connect their households to the city's water supply system through wells that collected water from the aqueducts: the amount they could take was based on how much they paid; they city measured the water in "dadi".
The dado was a little groove (about an inch wide), in the middle of a small stone plate that dammed the little channel of water. The amount of water that could flow through it corresponded to about 400 liters each 24 hours. Using this system one was able to contract for 1/2, 1, 2, 3, or more dadi of water. In order to keep track of these provisions in the underground world little maps were made (the oldest one dates from 1768) and tags or plates were fixed at each user's well, on which it was indicated precisely the name of the occupant, the exact location of the dwelling, the number of dadi for which the user paid, and a small plan of the that branch of the bottino. These users however corresponded to the wells from which the great palaces took their water, with this system serving only the wealthy landowners who had houses close to the route of the main aqueduct. The other residents, and especially the poorest, continued for centuries to use the public fountains, which were augmented on the outside with additional facilities, including new laundry basins.
The system continued to function in this way until someone finally thought of bringing water from the three springs on Mt. Amiata. In fact, there was an attempt already, quite similar, many years before in 1267, when they considered bringing water from the Merse River, at the Ciciano spring, about 30 kilometers as a crow flies, from Siena. The project turned out to be impractical, mainly for two reasons: the difficulty of overcoming the constantly changing slope of the earth , and second, when they calculated the incline from the beginning to the end they discovered that they would be able to deliver the water no higher than 288 meters above sea level, at the elevation of the lowest fountains, which would have created further hardships for the population that already had to descend a long slope in order to use the fountains.
For these and other reasons (not the least political ones), the project was abandoned and they sought to increase the development of the bottini.