Access to safe drinking water is limited in many isolated areas, such as the Amazon where Indigenous peoples frequently reside. Identifying safe forms of drinking water accepted by the communities could have positive health benefits for Indigenous peoples. Many Amazon Indigenous peoples traditionally prepare and consume a fermented beverage called masato, which is frequently the only form of water consumption. Despite its widespread consumption and evidence of the health benefits of fermentation, masato remains poorly investigated. We partnered with a Shawi Indigenous community in the Peruvian Amazon to conduct participatory photography to research masato preparation, and to characterize key cultural features and to assess the presence of total and fecal coliform bacteria by using a membrane filter technique. Pictures show that masato preparation is a key part of cultural practices and that there are clear gender roles in the preparation process. We found that 100% of communal water sources (26/26) were contaminated with coliform bacteria; by contrast, fewer, 18% of masato samples (2/11), were positive for coliform. This exploratory study suggests that fermented beverages like masato merit further investigation as they represent an Indigenous method to improve water quality in Amazonian communities where water safety cannot be assured.