We investigated SARS-CoV2 spread in the Canton of Ticino, in Switzerland, at the very beginning of the pandemic (end of February 2020 - beginning of March 2020) analyzing wastewater samples. We compared data obtained from clinical testing and wastewater analysis to explore spatial and temporal diffusion of the virus. Here we show that, based on wastewater analysis, SARS-CoV2 was already much further spread in the whole region than what it was supposed to be by clinical testing. Our study confirms the potential role of wastewater-based epidemiology (WBE) for monitoring pathogen dynamics within a population.