Selected human enteric viruses and viral indicators in drinking-water sources and treated waters: a review on prevalence and monitoring methods

Abstract

Viruses transmitted via contaminated water pose a major public health risk, requiring accurate detection and quantification in diverse water matrices. This review assessed the occurrence of selected human enteric viruses and commonly used viral indicators using 30,085 data points from 3094 sites across surface waters (e.g., lakes, reservoirs, rivers and streams), groundwater, treated effluents and reclaimed waters, and treated drinking water. Viral genomes were primarily quantified using reverse transcription-quantitative polymerase chain reaction ((RT-)qPCR), while infectivity was evaluated in a smaller subset of studies using cell culture approaches (e.g., integrated cell culture-PCR and cytopathic effect-based observations). Culturable coliphages were also reported as indicators of faecal contamination and as operational surrogates for treatment performance, but data in treated drinking water remain limited, emphasising the need to understand their strengths and limitations. Regulatory and guidance frameworks are evolving, with increasing emphasis on demonstrating virus log reduction through multi-barrier treatment and on risk-based operational monitoring (including somatic coliphages in some jurisdictions). Low-level virus detection remains constrained by the need to concentrate large sample volumes, particularly for on-site sampling at drinking water treatment works. Across the studies reviewed, reported viral genome concentrations spanned approximately 1.5-7 log10 genome copies/L, and culturable indicator concentrations varied widely across matrices. Recovery of both gene targets and infectious virus varied substantially between methods, indicating methodological challenges that can affect interpretation and risk assessment. Overall, the evidence supports standardised, multi-method monitoring (molecular and, where feasible, infectivity-informed approaches) and improved surveillance designs to better protect public health from viral contamination.