Figure 1. Schematic of experiment.

We collected settled solids from wastewater treatment plants and analyzed them immediately within 6 h to measure SARS-CoV-2 RNA concentrations and PMMoV RNA concentrations. The samples were then stored under different conditions (4 °C, −20 °C, or −80 °C) for different amounts of time and the SARS-CoV-2 RNA was measured again using the same analytical methods. The samples stored at −80 °C were first dewatered prior to storage. Created with BioRender.com.