Bacteriological and physicochemical studies of 72 well water samples were carried out over two successive dry and wet seasons in Bida town. Membrane filtration technique, Cultural and Biochemical tests were used for Bacteriological analysis while the methods of the American Public Health Association (APHA) were used for the physicochemical analysis. One way Analysis of Variance (ANOVA) was used to analyze all data generated. Bacterial counts of well samples tested were all above the limits specified by the Nigerian Standards for Drinking Water Quality (NSDWQ) and the World Health Organization (WHO). Only the mean feacal coliform counts (FCC) for the wet seasons were significantly higher (P<0.05) from the dry seasons value. Mean THC and TCC showed no significant difference over the dry and wet seasons. All physicochemical parameters recorded values in the wet seasons that were significantly different (P<0.05) from the values obtained in the dry seasons, except Turbidity, Total Suspended Solids (TSS), and Total Dissolved Solids (TDS). The most frequently occurring bacterial isolates for the dry and wet seasons were Streptococcus faecalis (24.6% and 20.9% respectively) and Salmonella paratyphi (22.1% and 14.7% respectively), while Klebsiella pneumoniae, Shigella dysenteriae  and Bacillus subtilis recorded frequencies of 0.7% , 0.9% and 1.5% respectively. Periodic sanitary surveillance and proper siting of wells should help mitigate groundwater contamination in Bida, Niger State.

Keywords: Physicochemical Parameters, Coliforms, Correlation.