Maria Cecilia R. Gomes ^1,2* Leonardo C. Andrade ^1,3 Bruna C. Lopes ² Milena P. Barbosa ^1,4 Cesar R. Mota Filho ²

• ¹ Instituto de Desenvolvimento Sustentável Mamirauá, Tefé, Brazil
• ² Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
• ³ Institute of Geosciences - University of São Paulo, São Paulo, Brazil
• ⁴ Universidade Estadual do Amazonas, Tefé, Brazil

Residents of remote areas in the Amazon often lack access to a water supply system and thus need to produce their potable water at home. This study examined the efficacy of household water treatments traditionally used by these communities to treat rainwater and river water, their predominant water sources. Samples of untreated, treated, and stored drinking water were collected from eighteen households in three communities in Central Amazon, Amazonas State, Brazil. We describe the materials and practices involved and traditionally used in each treatment technique – cloth filtration (water straining), chlorination, and sedimentation -, and their efficiency. In the samples we evaluate water quality analyses, as free chlorine, color, coliforms, and turbidity. The treatment steps for the separation of solids in river water were effective only for removing turbidity and apparent color. Straining river water after sedimentation had no relevant effect on water quality. Chlorination of rainwater was efficient in inactivating E. coli; however, all samples showed some level of contamination by E. coli. We found a significant difference (p<0,05) between untreated and treated river water turbidity, reduced by up to 22%. Untreated rain and river waters showed similar levels of microbiological contamination, close to 3.5 log CFU/100 mL of Escherichia coli (E. coli). Chlorine effectively removed microbiological contaminants in rainwater (median removal of 100%, 44.5% of samples with <1 CFU/100 mL). Yet, this treatment was less effective for river water (94% median removal, with 11% of samples with <100 CFU/100 mL and only 5.5% with <1 CFU/100 mL found in treated water), showing a significant reduction in both cases when the Wilcoxon test was applied. Sodium hypochlorite treatment showed the best results among the techniques evaluated in this study. It can be used in remote areas where rainwater is available for consumption. Microorganism concentration increased after water underwent water straining and sedimentation processes. These results suggest that the improper handling of water containers and materials used during treatment processes leads to contamination of water. Thus, more robust outreach and educational efforts are recommended to improve remote communities' water collection, treatment, and storage practices.