In this paper we review the current state of Water-related health Problems Caused by Protozoan parasites. There are various institutions of control and prevention of water related diseases caused by Protozoa in Developed Countries. Since 1970 water pollution has become a serious problem and is rapidly increasing day by day. Water pollution also brings undesirable micro-organisms, characteristic Pathogenic Protozoans (Acanthamoeba, Balantidium coli, Cryptosporidium, Entamoeba histolytica, Giardia intestinalis, Isopora, microsporidia, Naegleri fowleri) and causes harmful effect on human health. Human health depends upon the availability and quality of drinking water. Under the present study of Ganga water of Mirzapur is taken for two consecutive years (Oct 2022-Sep 2023) to (Oct 2023-Sep 2024) for Pathogenic Protozoan analysis.