U radu se opisuje moguća uporaba CPS ID3 podloge u mikrobiološkoj analitici morske i bočate vode za detekciju i enumeraciju bakterijske vrste Escherichia coli. Temelj dokaza vrste Escherichia coli na CPS ID3 podlozi je sposobnost ovih bakterija da proizvode enzim β-glukuronidazu. CPS ID3 podloga se pokazala pogodnom za detekciju bakterija vrste Escherichia coli osobito u uzorcima s visokim stupnjem mikrobne kontaminacije..; The paper describes potential uses of the CPS ID3 medium in microbiological analytics of marine and brackish water THEum in microbiological analytics f the  be the sourve of infection for humans or animals. for purposes of detection and enumeration of the bacterial species Escherichia coli. The basis for proving the species Escherichia coli on the CPS ID3 medium is the ability of these bacteria to produce the β-glucuronidase enzyme. The CPS ID3 medium proved suitable for detection of the bacterial species Escherichia coli, particularly in samples with high level of microbial contamination.