That it is for reasons of public health, to take account of the evolutions of the perception of the public, or finally of the developments in the analytical technologies, the quality of drinking water did not cease evolving/moving since the first filtration of water on sand which goes up in the medium of the XIXthcentury : the public utility of supply water became today compared to the supply of a product for daily human consumption : progress was multiple and has touched any other business fields such as : - techniques of production of drinking water : natural filtration of water ensuring their limpidity, with the treatments of clarification of surface water ensuring their very low turbidity, until membrane filtration constituting a physical barrier for the viruses and other cysts of protozoa : - the taking into account of the quality perceived by the final customer : the installation of networks of observers of the quality of water in the course of distribution, the study of the problems of tastes and odors, the satisfaction of those which have a too hard water for certain domestic uses ; Today, it is new challenges with which we are confronted : - how to take into account the requirement for quality to the "top of the most frequent use" and to regulate the delicate subjects of obligations of the public or private person responsible for the distribution whereas the quality of the interior private networks is not controlled : - how to satisfy everywhere and for all the standards of quality and to anticipate the not yet proven risks, in particular in the field of the micro biology ? how a better evaluation of the medical risks can replace the current standards of quality ? In addition to these challenges of quality of the water of topicality in the industrialized countries, another challenge is well-known other countries : that of "the water devide". We will develop the essence of the approach of it by underlining the results already obtained in several countries thanks to the joint work of the public panners and deprived for : - to solve in this beginning of the XXI century problems of drinking water supply of the 1,1 billion people who don't have which it today ? in the same way for the 2,3 billion which doesn't have cleansing ? - to observe and analyze, to retort the results obtained in several countries throughout the world, when the political good-will are combined with technical solutions and economic and financial means adapted.