An extensive debate on bacteraemias due to aquatic bacteria has recently developed in the Mailing List SIN. This topic was analyzed in two previous issues where the epidemics observed in two Dialysis Centers have been presented and discussed. The two experiences had in common the difficulty in identifying the source of contamination in industrial products commercialized as ''sterile''. In one case, the source of the epidemic could not be identified, in the other one it was discovered only incidentally thanks to a notice of the supplier company of the contaminated material. This underlines the importance of defining specific operating protocols in case of hospital epidemics and stresses the issues related to the professional risk and the potential legal implications.