Context: Water is currently considered the most critical natural resource on the planet. Numerous worldwide studies have shown that rainwater harvesting systems have been needed to meet different basic needs. One of the most important steps in planning a rainwater harvesting system is to use a method to determine The optimal capacity of collection and storage tanks Method: In this paper we present different concepts of authors of articles at a global level that refer to the use of rainwater, its capture and use avoiding that this resource is wasted and that it reaches the sewers and raking with the garbage found What happens is that they contaminate and cover these teachers causing flooding. Results: Research has shown that rainwater harvesting systems promote water saving in a variety of settings, such as stadiums, universities, schools, airports and residential areas. Conclusions: it is determined that rainwater has not been taken into account as a saving factor, nor the use of this resource with respect to an environmental impact. As for the concept of catchment and use of rainwater, it is taken into account as any kind of technical effort, simple or complex, arising from the initiative of some people to store it and be used later for farmers, toilet flushing, urinals and irrigation of gardens, washing of floors, among other. If you go into a cost benefit study to collect it and take advantage of it to be replaced by drinking water, it would show very good results.