Hazard assessment and categorization of microbiological risk in a water treatment and distribution system located in a municipality in the interior of Minas Gerais, Brazil

Consumption of non-potable water is a relevant public health problem due to the possibility of transporting numerous chemical and microbiological contaminants. In 2005, the Brazilian Ministry of Health created the National Program of Surveillance in Environmental Health related to the Quality of Water for Human Consumption (VIGIAGUA), with the primary purpose of managing risks related to water supply to human populations in Brazilian territory. However, VIGIAGUA does not have a methodology capable of characterizing or managing risks. The objective of this research is to create a working model to transform raw data into conceptual data related to low-, medium- and high-risk levels. The data used in the application of the model were obtained through the analyses of water-quality surveillance conducted by the Regional Health Management of Itabira, a municipality with less than 10 thousand inhabitants, whose history of water contamination is alarming. Twelve samples/month were collected between May 2017 and April 2018. The results of the treated water analyses were classified according to the presence of hazards and categorized into risk levels. The results showed 83.3% contamination by total coliforms at the treatment plant and 91.6% in the distribution system. The Escherichia coli contamination was 16.7% in the treatment plant samples and 45.2% in the distribution system. The system was categorized as "High Risk". The analysis of untreated water samples was carried out for the purpose of knowing the contamination pattern of the raw water of the region, finding 100% contamination by total coliforms and 97.2% contamination by E. coli.