The Guarani Aquifer was the name that, in 1996, the Uruguayan geologist Danilo Anton proposed to name an immense aquifer that covers parts of the territories of Uruguay, Argentina, Paraguay and mainly Brazil, occupying 1,200,000 km². At the time, it was considered the largest in the world, capable of supplying the Brazilian population for 2,500 years. The aquifer corresponds to a succession of sandstone layers, interspersed with more clayey, lens-shaped layers. Thus, we can consider the Guarani Aquifer, a Guarani Aquifer System. Its layers are not all originated from dunes of an ancient desert, such as those of the Botucatu Sandstone, but from intercalations of layers with different origins and permeabilities. The Guarani aquifer supplies 200 municipalities in the state of São Paulo alone with water that absorbs rain, clean and potable. It is considered one of the largest underground water reserves in the world and the largest in South America. FOZ's headquarters are in the city of Botucatu, 235 km from São Paulo and is located on the edge of the so-called Guarani Aquifer. Perhaps a coincidence, perhaps the destination, it was in the city of Botucatu that everything started for both the Guarani Aquifer and FOZ.