The three wells are located in a basaltic fissural zone and exploit basaltic basal aquifers, at depths between 89 m and 284 m. Specific capacity ranges between 1.4 L/s.m and 100 L/s.m (Cruz, 2004). Since 2003, the total volume of water abstracted is almost constant throughout the years despite some minor differences in the past decade and following an increase in the beginning of the century, reflecting a small variation in the total population of Ponta Delgada, which is the main driver controlling demand.