The hidden treasure of Venice
Visiting Venice, tourists cross a campo or a campiello – medieval Italian words that indicate large or small squares –, they see the above ground urban layout… and go on. They do not imagine that, under their feet, there is a secret, a unique artwork, a hidden treasure.
Venice. Campiello of the Levantine School, by Antonello Vincenti (1926-2021)
Venice is a city built on the sea. But it lacked a primary good: there was no drinkable water. Digging a well in a lagoon is not a good idea: wherever you drill you will find only muddy and salty water. It was therefore necessary to create cisterns, to channel the rain into them and top them up with fresh water from nearby rivers.
Venice, the Grand Canal in the Moonlight by Karl Heilmayer (1829-1908) – PD-US?
The concern of the Government of Venice was to provide drinkable water for the people, especially the most needy, since only the wealthy people could afford a private well. The local rulers decided to create public cisterns for Venetians, and they paid the burchieri – the helmsmen of special boats that carry fresh water from nearby rivers – to supply the wells of the city at the state’s expense. As early as 1334, the Venetian government issued a law relating to the gutters of houses that must lead rainwater into the wells. In 1536 the Provveditori alla Sanità – Health Officers who had, among their many activities, to take care of the hygiene of the cisterns – forbade barbers, dyers, butchers, furriers, painters and decorators, and anyone who used water for his activities, that is, all shop owners, to take it from public wells, otherwise the penalty was six months in prison and 50 Venetian Lire (equivalent to months of a worker's wages). These artisans had to buy it from the Acquaroli, a guild specializing in wholesaling water.
The Courtyard of the Doge's Palace in Venice, by Rudolf von Alt (1812-1905)
Fresh water was a precious commodity in Venice and therefore had to be regulated. The drinkable water was free for Venetians but rationed: the wells were locked and citizens could only take water twice daily to the sound of a bell, when they were opened; at other times, water had to be bought retail.
Campo San Canzian, Venice, by John Singer Sargent (1856-1925)
The construction of the Venetian wells is a unique masterpiece of hydraulic engineering to obtain pure drinking water. The construction of the cisterns was entrusted to the so-called pozzeri – well makers –, a small group of the masons' guild that deals specifically with the wells "for the use of Venice", an art that was handed down from father to son.
Cross section of Campo San Trovaso well????
It began by excavating a circular, square or polygonal large pit in the shape of a truncated pyramid, no more than 6 meters (19.7 feet) deep. Its walls were made of clay: the work was carried out in layers, always starting from the bottom of the pit and going up along the walls and this material was well handled to ensure impermeability and therefore facilitate the collection of fresh water and avoid its dispersion. The so-called canna – the cylindrical part of the well from which to draw water – was 1 to 2 meters wide (3.3-6.6 feet), with a stone at its base. It was built of bricks cemented with clay mixed with sand, placed in the center of the pit, and reached down to ground level. Above it was placed a vera, that was a puteal to protect the canna. At first it was a simple stone element, with only a security function but over time, it became a rich and picturesque ornament of squares and courtyards.?
Puteal, Campo of the Ghetto Nuovo
Of the remaining space, the 6/10 were filled with sweet sand – silicon sand, sea sand, or fine gravel, cleared of other substances – which was compacted to allow the construction of cassoni, that was a covered tunnel, in which fresh water was poured or rainwater conveyed from the roofs of the houses. It was built with dry stone walls and partially filled with sand to filter but also to control the momentum of the incoming flow, which goes around the canna and which is close to the walls of the cistern: its function was to increase the purification of the water that entered the canna. Only 4/10 of the reservoir were filled with fresh water. The water, mechanically purified first by the sand of the cassoni, then by the sweet sand and finally by the one that cemented the canna, became perfectly filtered water, ready to drink.
Campo S. Angelo, Venice, by Canaletto (1697-1768) – PD-US