Supplementary material

Figure S1. Scatterplot (raw results) from PMMoV dPCR analysis on the Qiacuity® platform. Blue dots represent positive partitions, where amplification occurred (the fluorescence intensity is high), while grey dots represent negative partitions. The red line indicates the threshold used to discriminate between positive and negative partitions. Final results are calculated based on the number of positive partitions detected by applying Poisson statistics. As no positive partitions could be detected either in the negative control of extraction or in the dPCR negative control, the space between positive and negative partitions of the environmental water sample was extremely clear (with no rain), showing the successful amplification of PMMoV target in the environmental water sample.

Figure S2. Temporal variations of PMMoV concentrations, measured upstream of Paris (Choisy-le-Roi, black diamonds), downstream of Paris (Triel-sur-Seine, dark blue squares), in sewage water at Clichy (light blue triangles), and different simulated concentrations (green curves) at Triel-sur-Seine: (A) Hypothesis 1, tributary concentration assumed to be equal to the one of Choisy; (B) Hypothesis 2, with Marne River; and (C) Hypothesis 2, with Oise River. Pink curves in panels (B) and (C) corresponded to the simulated concentrations in the tributaries in case of an input of this tributary, allowing it to fit with the observed measurements at Triel. The pink dashed line represented the mean estimated concentrations in the tributary.

© A. Langlais et al., published by EDP Sciences, 2026