Metropolitana Milanese guarantees high-quality water to its customers, using existing deep wells and drilling new ones in outlying areas with little or no pollution whatsoever.
In case of contamination, often occurring in anthropization areas, Metropolitana Milanese purifies the water before distributing it. The most commonly used purification methods in Milan are carbon filtration and aeration.
Where possible, the water is disinfected using sodium hypochlorite and exposure to UV radiation. A reverse osmosis plant has been operating since 2008. In some cases, both aeration towers and carbon filters are used to eliminate different kinds of pollutants.