Wastewater surveillance of SARS-CoV-2 can be useful in providing information about the prevalence and the possible emergence of new variants in a community. Although wastewater-based approaches have been implemented globally to monitor the virus, there remain various challenges and knowledge gaps that make it difficult to fully and reliably interpret the data obtained; for example, the fate of SARS-CoV-2 in sewer systems is not well understood. In this study, Li and colleagues used a sewer reactor to analyse sorption, stability and persistence of SARS-CoV-2 RNA in sewers. The authors found that SARS-CoV-2 RNA accumulated on solid compartments and biofilms in sewers, which offered more niches and sorption sites. In addition, they also reported that biofilms may facilitate the decay of the virus and/or its genetic fragments in sewers, which might lead to the loss of the RNA signal and could thus affect the analysis, particularly in low-case settings. Moreover, the results also suggest that biofilms are a reservoir for viral RNA that accumulate, retain and subsequently release RNA fragments back into wastewater, which would have an impact on the interpretation of surveillance data. In sum, the results of this study could aid in advancing the efforts in wastewater surveillance.