The May issue of Hydro is online. “Use of ground water in condos” is highlighted on page 14, showing the importance of a technical normative base to make sure that the use of ground water does not cause future problems. It is a consensus among experts to speed up authorizations to prevent illegalities and, on the other hand, that existing legislation must be technically better founded. See on page 22 the article “ETA sludge: is it possible to concentrate it through floatation by dissolved air?”, where the results demonstrate that the flotation process by dissolved air using cationic polymer in the flocculation is satisfactory, turning this technology suitable for the ETA sludge densification process. And on page 30 the article “Alternative techniques for urban drainage”, which shows that it is possible to design an alternative system in a consolidated urban basin and obtain a positive response, reducing both the excess flow and the construction costs. However, for a better cost benefit it is necessary to deepen the studies in devices installed in loco and to evaluate the maintenance costs. This issue brings also the new “Submersible pumps” and the updated “Drives and automation for water plants” buyers’ guides.