A battery of in vitro short-term genotoxicity tests revealing different genetic end-points was used in this study on non-concentrated and concentrated drinking water samples. The following in vitro biotests were performed: the Ames/Salmonella typhimurium test11 using TA97a, TA100 in TA1535 strains in the presence and absence of bio-activation (± S9); the Zimmermann test12 using yeast Saccharomyces cerevisiae diploid D7 strain in the presence and absence of bio-activation (± S9) and the comet assay using human hepatoma cell line (HepG2 cells).13