Beyond the disequilibria of it offers of water the populations, aquesto of the availability and of the conflicts for its use also they present preoccupying seusaspectos. Thus it is that some countries present scarcity hdricaabsoluta, such as Kuwwait, Egypt, Saudi Arabia, the Barbados, Singapura and CaboVerde; others as Burundi, Algeria and Belgium suffer of dry chronicle; emregies as the half-barren northeastern have the alert one of scarcity and in several decurrent conflicts of disequilibria between demand locaisafloram edisponibilidade, such as Madrid and Lisbon for the River Tejo. Ahead of this turbulent scene, the underground water vemassumindo an importance each time more excellent as source of abastecimentodevido to a series of factors that restrict the use of the guassuperficiais, as well as the increasing o increase of the costs of its captation, aduoe treatment, the underground water is being recognized as alternative using viavlaos and has presented increasing use in last years, gotten atravsde leased and well constructed wells. Beyond the inherent problems and easiness decontaminao to superficial waters, the biggest interest for the underground use dagua comes being despertado, for the biggest one offers of this resource and emdecorrncia of the technological development, what it promoted an improvement naprodutividade of the wells and an increase of its useful life. The underground water nothing more is of what filtered water nosubsolo, gift in the intergranular spaces of ground or in the breakings dasrochas. For one better agreement is basic the notion of CicloHidrolgico. For effect of the solar radiation, the elagos waters of the seas, rivers are evaporated and formed clouds. These when finding cold chains of ploughed decreases atmospheric pressures are condensed and precipitated under the form dechuvas, hail or snow. Of the precipitated water, one has left evaporates mesmode before to reach proper the ground or to be intercepted for leves of vegetables; efinalmente, another part is infiltrated in the subsoil forming water-bearing reservatriosnaturais of underground water or.