Nowadays, Environmental problems are the most important sensations in human populations. It can be the problem of monitoing industrial effluents, managing a sewage water system, assessing the quality of ground water and considering the pollutants of environment. For resolving each of these problems, it is necessary to choose a sample of population. Sample must be representive and informative. Sampling consists of selection, inclusion and measurement variable of interest of a part of the population. In these situations, composite sampling reduce analytical costs by compositing several samples into one and analyzing the composited samples.
