The effect of UV radiation on viral inactivation was modelled using linear regression analysis to predict the UV fluences necessary to achieve 90 (D90, corresponding to1-log) to 99.99% (D99.99, cor-responding to 4-log) reductions. In addition, measured infectivity data were compared to estimated infectivity using the qPCR-based approach developed by Pecson et al. (2011). The mathematicalapproach used in these experiments has been applied to several other viruses (e.g., Human Adenovirus, JC Polyomavirus and MS2 bacteriophage) to calculate estimated inactivation, which hasshown a good correlation with actual results (Calgua et al., 2014).The formula applied to estimate the infectivity of HEV from qRT-PCR data was as follows:log(Nt/N0)infectivity = c * log(Nt/N0)qRT-PCR,where c is a measure of the lesion rate in the targeted genomeregion relative to the inactivation rate of the virus. Basically, by analysing experimentally derived measurements of infectivity and qRT-PCR decay, we can calculate the value c. Then, as long as the same genome region is used, we can estimate infectivity from qRT-PCR data with this parameter in future experiments.To analyse the efficiency of the FCS preparations, the water samples were measured pre- and post-treatment in duplicate for eachcondition and for each virus. Log Reduction Values (LRVs) were calculated using the following formula:LRV = log(pre-treatment)-log(post-treatment).Statistical analysis were performed to compare LRV between methods by ANOVA. All analyses were performed using the R software program (version 3.0.2).