In the Brazilian city of Rio, thousands of residents have been facing a drinking water crisis. Experts have recorded an abnormal amount of geosmin, a substance produced by micro algae that proliferate in water. Authorities and the company in charge of water distribution insist the substance isn't dangerous. But many residents are complaining of nausea and stomach aches. Our correspondents Fanny Lothaire, Pierre Le Duff and Laura Damase take us to the areas of Rio most affected and also to the source of the problem.