'The floating aggregates known as foams are harmless to humans'. This is one of the main conclusions reached in a study undertaken by the University of Málaga with the collaboration of Hidralia and companies from the Costa del Sol’s water sector. The report was entrusted last July to the lecturer Francisco Ignacio Franco from the Crystallography and Mineralogy Department by the public, private or mixed companies responsible for managing the complete water cycle in the Costa del Sol. In total, up to 45 samples of floating aggregates or ‘foams’ were analysed. In all of them, a foamy appearance was observed, so the aggregate has a very low density. Aggregates are formed of a liquid phase (seawater) and a solid phase. Inaddition, the lecturers responsible for this study determined that the components of the foam are very similar to those that form part of our geology, they are completely harmless to health, and generally have a very small particle size. The samples analysed indicate that the water quality is very good and the ‘foams’ come from a natural marine environment and do not have a faecal origin.