The most considerable result is the high contamination frequency with P. aeruginosa. Baumgartner and Grand (2006) reported 25% of the spring water samples from bottles and 24.1% of the water samples from coolers positive for P. aeruginosa, instead in Kokkinakis et al. (2008) study no P. aeruginosa was found. This bacterium is known to be an important agent of nosocomial infections, with multidrug-resistant strains in hospitals being of particular concern ( Felfoeldi et al., 2010, Huq et al., 2008 and Morais et al., 1997). Because elderly and immunocompromised people are at greatest risk of infection, drinking water in hospitals and institutions should contain as few P. aeruginosa as possible.