From Table 2, the three methods showed an increase in DNA damage with the higher concentrated level of water samples. The water sample, X1, was demonstrated with genotoxicity at all three concentrated levels by the biosensor and the other two genotoxicity bioassays. The water samples X2 and X3 were tested as having no genotoxic/mutagenic potential by the Ames test. However, the Comet assay demonstrated X2 and X3 water samples containing genotoxic compounds at 50_ concentrated level. This may be attributed to the fact that the Comet assay is more sensitive than the Ames test [31]. Also, the dsDNA/Nano/Au biosensor showed similar results to the sensitive comet assay that X2 and X3 water samples were identified with genotoxicity at the 50_ concentrated level. From the results, the biosensor could be used to distinguish different contamination level.