Fig. 1: Spatiotemporal load patterns of pharmaceuticals and viral gene copies in wastewater.

Wastewater loads from every 13th day between January 2021 and June 2024 are displayed. Data are shown for individual treatment plants according to the abbreviations on the y axis. ZH, Zurich; BL, Basel; BE, Bern; SO, Solothurn; CH, Chur; SZ, Schwyz; GE, Geneva; LA, Lausanne; NE, Neuchâtel; LU, Lugano. These are arranged first by language in the region then by catchment population size. The colouring represents the load values for pharmaceuticals (mg d−1 per 1,000 people) and viruses (gc d−1 per 1,000 people) with linear colour scaling. For pharmaceuticals, each space refers to an individual sample of a particular day, and for the viral loads, each space reflects values from the centred 7-day median. White spaces indicate data exclusions owing to rain-related increases in wastewater volumes exceeding maximum threshold values or owing to the absence of sampling. The black-outlined spaces represent pharmaceutical loads from samples with concentrations below the limit of quantification (LOQ), which are estimated on the basis of half the LOQ value.