A bit of history
Bonvesin della Riva (b. ~1240 – d. ~1315), Italian author and poet, reports that already back in 1200s there were 6000 phreatic “live water” wells in the Milan area.
The abundance and the surface nature of the groundwater (2…3 m or 6…10 ft below ground level) meant not very deep wells were required, meaning that they were exposed to human and animal contamination.
In a public tender called in 1877 to build waterworks, 13 companies have bidden; the project proposed by Società Italiana Condotte d'Acqua was chosen in 1881, which involved transporting water from the source of the Brembo river to Milan.
Bergamo residents protested, causing the project to be abandoned and a new tender called.
Finally, the proposal of the Municipal Technical Department coordinated by Mr Poggi, an engineer, prevailed in 1887, suggesting to continue pumping water from the underground water table using wells of suitable depth.
The first two experimental wells were built in the Arena zone in 1888 and the water was used by the new residential neighbourhood rising between piazza Castello, Foro Bonaparte and via Dante. Two large accumulation reservoirs “hidden” inside the keeps of Sforzesco Castle were built to adjust the water supply pressure.
The municipality then decided that the underground water table would be the only source of drinking water, discarding ideas to pump water from suburban springs (many were available at the time, some with high water flow rates) or from mountain sources (Val Brembana).
The abundance of drinking water made building public baths and facilities possible, equipped with large pools, like the ones built in via Argelati. This meant that almost anyone could afford using the bathing establishments which may have been less elegant but equally functional as the ones that the better-off Milanese population had already used for many years, e.g. the prestigious and elegant Kursaal Diana in Porta Venezia.
After the Arena, the second pumping station was built in 1898 at the Cagnola roundabout (now piazza Firenze); the Parini station, close to the current piazza della Repubblica, was added in 1903.
The Armi station, built in 1904, is the oldest of the still existing ones.
In 1910 there were already ten pumping stations.
The Anfossi station was built in 1915.
At the end of the ‘20s, when there were seventeen stations, with a total pumping capacity of about 6 m3/s (1,320 imp gal/s), a slight lowering of the water table began and this forced a change in the extraction system. Electric, axial-flow pumps were used to pump the water into special reservoirs and from there it was pumped into the piping network.
In 1948, the San Siro station designed by Gio Ponti was commissioned.
The problem of the water quality in the water table developed from the sixties. In fact, the water table was heavily contaminated by untreated industrial discharge. After years of progressive indiscriminate public and private exploitation of the phreatic water table, it began to show signs of “tiredness”. The phenomenon was reversed from 1975, due to the closure of the heavy industry that had been the major cause of the degradation of the water table water. During that time, the rising of the water table level led to flooding of basements, underground car parks and metro installations.
In 1988, one hundred years after the modern drinking water network had been built, there were 34 stations with a total pumping rate capacity of about 30 m3/s (6,600 imp gal/s).
In the meantime, the waterworks began to introduce purification technology to ensure water quality and to comply with the increasingly restrictive European laws setting limits to the concentration of pollutants in the drinking water.
The first carbon filtering system was built at the Vialba station and was commissioned in February 1992.
n May 1994, the aeration towers were commissioned in the Novara, Comasina, Suzzani, Chiusabella and Cimabue stations.
The reverse osmosis system was introduced at the Gorla station in September 2007.