Valuable material flows in the sewers to photograph not only the habits of the citizens who feed the waters, from the consumption of drugs to the use of drugs, but also the progress of the Covid 19 epidemic. traditional monitoring techniques. This is demonstrated by a study conducted in Lombardy during the first pandemic wave, published on the ‘medRxiv’ preprint platform by scientists from the ‘Mario Negri’ Institute of Pharmacological Research Irccs, Department of Environment and Health, and of the State University of Milan, Department of Sciences biomedical for health. The authors of the work, conducted with the participation of the Lombardy Region, followed the evolution of Covid-19 looking for the coronavirus Sars-CoV-2 in urban wastewater through “an innovative approach called ‘wastewater epidemiology’, explain from ‘Mario Negri ‘and Statale announcing the results of the study, “first in Italy for the number of samples analyzed”: the data prove “the reliability of the epidemiology of wastewater as a tool for monitoring the epidemic trend of the virus in the population, able to to anticipate the trend of the epidemic curve by 7-14 days with respect to existing surveillance systems “. The research involved 8 Lombard cities, selected from the areas most affected by the first wave of Covid-19: Bergamo, Brembate, Ranica, Brescia , Cremona, Crema, Lodi and Milan. In their inlet manifolds, 107 samples were taken between the end of March and mid-June 2020. Viral RNA was detected in 65, equal to 61% of the total, “one of the highest percentages of positivity among the studies conducted in other European and non-European countries in the same period”. Spikes of 80% were found in the Bergamo area, the epicenter of the first wave of Covid.