Water supply in the municipality of Ponta Delgada originates entirely from groundwater sources and on the exploitation of 45 springs or groups of springs, when discharges are closely located, and three drilled wells. Springs are spread along two groundwater bodies, in the western sector of the São Miguel Island, associated with two active central trachytic volcanoes (Sete Cidades and Fogo), and with discharges from perched aquifers. For water supply management purposes 25 supply zones are defined, 23 of which for direct distribution to users living in Ponta Delgada while the remaining two transfer water to the supply systems of the neighboring municipalities of Ribeira Grande and Lagoa (Fig. 2). The Ponta Delgada water supply system also encompasses 56 reservoirs with a total storage capacity of 38,890 m3, sufficient for a three day provision period.