
Well head at Campo Santi Giovanni e Paolo
While walking around Venice and admiring its architecture, you can’t help but notice the beautiful, architectural wells in almost every large square (campo). They were ingenious works of art and engineering that were designed to supply drinkable water to inhabitants who, ironically, were surrounded by water.
The wells of Venice, vere da pozzo,were not true wells as they did not draw water from underground aquifers. They were underground cisterns designed to collect and filter precious rainwater, and served Venetians from the 5thcentury to about 1884 when water was piped in from the mainland.
The construction was both complex and expensive. Highly skilled builders known as pozzeri,along with bricklayers, supervised the digging of the cisterns. Sons followed fathers and grandfathers into the business. It was an important trade and highly valued.
First a large area was selected; hence wells were built in the campi or corti of Venice. The area was dug to a depth of 5-6 meters below ground and sea level. The recess was lined with a waterproof layer of clay to prevent infiltration of salt water and dispersion of fresh water from the tank. In the center a tall tunnel (cassone or canna da pozzo) formed the well shaft; this is where the local inhabitants dipped their buckets to obtain fresh water. The rest of the recess was filled with sand and gravel. Each stratum consisted of a different size stone creating a graduated filter. Then 2 to 4 manholes (pilelle) were built close to the edge of the reservoir to collect the rainwater as far from the center tunnel as possible so that the water could be purified through the various layers of sand and gravel.

Well head at Cà d’Oro
The crowning glory was the vera, the well-head, which was a work of art in its own right. Early ones were built with stones taken from ancient Roman ruins: capitals, pillar sections, and cinerary urns were adapted for use as vere. The Republic encouraged the aristocracy to participate in the construction of rainwater wells; in return, the family’s coat of arms or inscriptions could be carved into the vera. Venice’s Administration also developed a system to check and maintain the wells.

Doge’s Palace well head
Wells were capped with heavy, iron covers and locked for most of the day. Sometimes only the local priest kept the key to unlock them twice a day, morning and evening, at the toll of the “well bell” calling residents to fill their buckets. At the height of Venice’s prosperity, there were over 6,500 wells. While no wells are in use today, about 600 remain in the Venetian campias a testament to the history and art of this engineering marvel, which perhaps could be adapted today in areas of the world suffering from drought.

Rainwater well in the cloister of Trinity inside the monastery of Santa Maria dei Frari
i did not know this! thank you for the info.
anne