Over the last few summers in Europe, increasingly hot and dry, we are experiencing a new great problem, the drought, associated with mugginess and insufficient winter and spring rainfall that do not allow the restoration of water reserves. Forecasts for the future are certainly not encouraging at the global level. It is in fact estimated that about half of the world population by 2025 will live in conditions of water scarcity, whose quality is definitely lowering in different parts of the world.