Rio de Janeiro's State Water and Sewerage Company (CEDAE) has issued a statement that “all tests conducted show that the water is within the parameters required by the Ministry of Health, and proper for the consumption", following complaints about water quality and a run on bottled-water.
Residents across the city have claimed that municipal water was cloudy, muddy, gave off a strong smell and that the taste had changed.
CEDAE attributed the problem 9 January to a high level of geosmin, an organic substance produced by algae and assured residents that the substance poses no health risk. The company has fired the head of the Guandu treatment plant, which supplies nearly 80 percent of Rio's drinking water.
Police have investigated whether CEDAE employees or a third party may have committed a crime resulting in contamination of the water supply. Agents carried out investigations 16 January at the Guandu water treatment plant in Nova Iguaçu, where the presence of geosmin was detected the previous week. The company revealed that it was adjusting its filtration system of water indicating that it would utilise pulverised activated carbon in treatment from the initial stages. Site investigation revealed that activated charcoal had already arrived at the Guandu River treatment plant on January 10. Activated charcoal is used in other Brazilian states where geosmin blooms are more frequent.
Experts at Federal University of Rio de Janeiro Polytechnic School (UFRJ) have confirmed that addition of activated charcoal in water treatment is normal but that the current situation could prove difficult to manage. The University's Issac Volschan has linked the change in water quality to environmental and/or human causes, stating that a combination of nutrients in the water with solar radiation could lead to the algal blooms and development of other bacteria, and suggested that untreated sewage could be in rivers in the catchment area of the Guandu River.
The CEDAE statement has been followed by a proliferation of counterassertions of considerable contamination by fecal coliforms, which authorities have described as "fake news".
The Rio de Janeiro Secretariat for Sanitary Surveillance and Control has completed analysis of water samples supplied by CEDAE, with first reports indicating that the water is satisfactory for turbidity, chlorine, fluorine, pH, total coliforms and Escherichia coli. These indices confirm the potability of the water, according to Ministry of Health parameters.