Correccions

The venetian well is an architectural structure used in the city of Venice in past ages for the supply of drinking water.

Currently, more than 600 venetian wells are survived only as an ornamental complement but they are essential and contribute in a fundamental way.in the planning of the city.

History The water supply was always fundamental problem in Venice and its surrounding islands.

Considering the particular hydro-geological features of the lagoon, citizens already started in the Middle Ages the building of underground cisterns, commonly defined "wells".

For its part, the government of the island encouraged, promoted and coordinated the construction of water systems In 1322 the Maggior Consiglio decreed the construction of fifty wells.

In 1386 was founded the "Guild of Acquaioli." In 1424 another thirty wells were built.

In the eighteenth century, there were 157 public wells, to which you had to to add many thousands of private wells [1], so much so that in 1858 the Venice Municipal Technical Office estimated the presence in the city of nearly 7,000 wells (6,046 public and 180 private wells, over 556 already buried).

During maintenance operations were brought to light the rests of a well in the same Piazza San Marco and was engraved in the pavement track of its location.

In the nineteenth century, with the making of the municipal aqueduct, the use of wells as a source of water supply was slowly abandoned until they ceased altogether.

For safety reasons, the top of the wells which are no longer used was closed with metal covers or in cement.

Venetian wells differs from the ordinary artesian wells as for the specific hydro-geological characteristics of the Venetian lagoon, the water was not obtained by accessing an underground source but only by collecting and filtering rainwater, taking advantage of the clayey nature - and then substantially impermeable - of venetian subsoil.

The construction of a well was somewhat complex.

It was necessary first of all to have a sufficiently large collecting area around the well itself, towards which converge the rainwater: for this reason the Venetian wells are located almost exclusively in the "campi" or in the wider courts.

Once identified, the area of a rectangular or square, was dug for a depth of five or six feet, covered with a thick layer of impermeable clay and filled with layers of different thinness of sand, which held the filter function.

Rainwater was collected using two or four manholes in Istrian stone, called "pilelle", arranged symmetrically in relation to the pipe of the well.

To limit losses, under manholes was built a brick structure in the shape of a bell, open at the bottom, to convey as much rainwater as possible directly to the sand filter.

The whole area surrounding the manhole was also elevated slope in order to promote rainwater harvesting.