There are major environmental and public health risks when water is contaminated by both organic and inorganic pollutants. The physico-chemical parameters of Jahaj Wali River water (Rajgarh, Alwar) before and after photocatalytic treatment with ZnO under solar irradiation are compared in this study. Important variables were examined before the mansoon, including pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), total suspended solids (TSS), and electrical conductivity (EC). The results show improvements in DO levels and notable decreases in turbidity, COD, BOD, and TSS. The results show that ZnO-assisted solar photocatalysis is a cheap, efficient, and sustainable way to enhance river water quality.