The April/May/June issue of “Hydro” magazine is online. The edition highlights the “Directory and yearbook of the Brazilian basic sanitation sector”, on page 20, a survey that brings up-to-date data on the country's sanitation sector, showing that the country's largest cities entered the first year of pandemic, in 2020, with deficits in water supply and sanitation. Also noteworthy are the numbers of 100 largest Brazilian cities, presented in annual survey of Instituto Trata Brasil. See on page 30, the article “Migration to the individualized water metering system in old buildings”, which provides a guide that can help professionals to retrofit existing buildings in a planned and safe way. A reduction of up to 30% in water consumption is estimated after implementation of new charging modality. Furthermore, on page 42, the article “Ion exchange resins for nitrate removal”, showing that, with the release of irregular sewage discharges or use of simplified disposal solutions, one of elements present is ammonia, which contaminates water for public supply. This issue also brings the update “Filtration systems”, “Pumps” and “Water flow meters” buyers’ guides.