Waterborne viruses in urban groundwater environments

The proportion of global population using urban aquifers as drinking water sources increases every year and indeed the groundwater quality is not monitored adequately. Although norovirus has been identified as the first cause of groundwater-related outbreaks, the surveillance of waterborne viruses has been rather neglected. From ageing or disrupted sewer systems, occasional sewer discharges (e.g. combined sewer overflows, storm runoff), to poorly managed reclaimed water infiltration practices, multiple are the pathways that cause groundwater quality deterioration. This study revises the main viral contamination sources and the factors affecting viral contamination of groundwater bodies in terms of transport, inactivation, and survival of the viral particles. It also summarizes the methods used for those reporting the presence of human viruses in urban groundwaters. A total of 36 articles have been included in the method survey spanning a period of 24 years (1999–2022). There is a need of systematic monitoring considering representative set of waterborne pathogens. The evaluation of the presence of human adenovirus seems a useful tool to predict the presence of other waterborne pathogens in groundwater. Large volume sampling methods, but also new passive sampling methodologies applied to groundwater, coupled to target massive sequencing approaches may elucidate the range of pathogens capable of contaminating urban groundwaters for further evaluation of risk.