Groundwater is an essential drinking water source for humans. However, improper groundwater management leads to fecal contamination and waterborne diseases caused by viral pathogens. Therefore, this study aimed to investigate norovirus (NoV) contamination by conducting nationwide monitoring over five years (2019-2023). Groundwater samples were analyzed for water quality parameters, indicator microorganisms, NoV prevalence, and viral genotypes. Water quality was assessed for temperature, turbidity, and residual chlorine, whereas microorganisms were analyzed for total coliforms, Escherichia coli, and NoV genotypes. Of the 600 sites, 11 (1.8%) were NoV-positive, irrespective of season or location. Low residual chlorine levels (0.02-0.75 mg/L) were observed, possibly limiting viral inactivation. Total coliforms were detected in only three NoV-positive samples, and E. coli was absent. NoV genotypes were identified as GI.1 and GII.4, with GII.4 being the most frequently detected genotype. The present study demonstrated that periodic monitoring and expanded nationwide efforts are required for effective groundwater management and public health protection.
Keywords: groundwater; norovirus; norovirus genotype; water quality.