Aims: This study was undertaken to further understand the processes affecting the persistence of enteric viruses in groundwater. Methods and Results: Varying temperature, oxygen and nutrient levels were tested in the presence and absence of groundwater micro-organisms to determine which of the factors tested had dominant influence on the decay of Escherichia coli , the bacteriophage MS2, poliovirus and coxsackievirus. The results indicated that the most influential factor affecting the decay of the viruses and E. coli was the presence of groundwater micro-organisms. The results also implied that temperature, the presence of oxygen and nutrient levels indirectly influence viruses and E. coli decay by influencing the activity of the groundwater micro-organisms. Conclusions: E. coli and the viruses displayed maximum decay under aerobic conditions, at 28degreesC without the addition of nutrients in the presence of groundwater micro-organisms. Significance and Impact of the Study: The results suggest that if the mode of action of the groundwater micro-organisms could be determined then the decay of viral pathogens in recharged waters may be more easily predicted.