Microbiological analysis of filtered water by domestic filters in hospital environment

Abstract

Drinkable waters have been described as reservoir for diverse microorganisms. Domestic filters for trading may be found regarding technology and prices, and its manufacturers guarantee the pureness of the processed water by their equipment, some times in a mistaken way. In a hospital environment the water quality control is crucial for developing methods to reduce infections incidence To verify the role of the domestic filters as source of water contamination in hospital environment, a study at water samples obtained by filtration was performed before and after filter's retro-washing, from 26 filters installed in different points of the hospital. For the control group, 17017 filtered water samples were analyzed from hospital's taps, collected next to the analyzed filters. The samples were microbiologically evaluated through quantitative cultures for mesophiles bacteria and fecal and total coliforms. Chlorine levels surveillance was also carried through. No contamination of the network water samples was verified and its chlorine level stead on 1.5 ppm. Considering culture oft he filtered samples before and after retro-washing it was not observed development of fecal or total coliforms, however, it was evidenced the presence of mesophiles bacteria in 19.3% (p=O, 056) whose counting varied from 30 to 100 CFU/ml, with the chlorine levels varying from 0.0 to 1.5 ppm. This method of water filtration does not assure its expected pureness, since the microbiologic quality of non filtrated water was superior.