Diatom plays an important role in Forensic Science and in the studies of water quality. Diatom acts as a supportive evidence for ascertaining the cause of death as well as the place of drowning. Presence of diatoms in the distant vital organs is an important method to distinguish between ante-mortem and post-mortem drowning. It is possible to pinpoint the site of drowning, if diatom species recovered from the tissues of the corpse are compared to that found in the water body from where the corpse is recovered. In the present study, 10 water bodies located in various parts of Mumbai were sampled for the study. Isolation of diatoms was carried out using acid digestion method. Total 35 species of diatoms were isolated and characterised. The diatom species identified belong to the following genera: Gyrosigma, Navicula, Melosira, Pinnularia, Surirella, Hantzschia, Eunotia, Fragilaria, Nitzschia, Gomphonema, Cymbella, Cyclotella, Neidim, Caloneis, Synedra, Epithemia, Frustulia. The information obtained helped to create a reference database on diatoms which can be utilized in future for ecological assessment and ready reference in drowning cases