Floating communities exist throughout the world. Many live on water with a high pathogen load due to difficulties associated with sewage management. In Claverito, an informal floating community in Iquitos, Peru, we conducted a controlled experiment to test the ability of water hyacinth (Eichhornia crassipes) to remove Escherichia coli from water. When river E. coli concentrations were at or below ~1500 CFU 100 mL-1, water hyacinth reduced shallow concentrations (8-cm depth) down to levels deemed safe by U.S. EPA for recreational use. Above this threshold, plants were able to reduce E. coli levels within shallow water, but not down to “safe” levels. At deeper depths (>25 cm), there was evidence that plants increased E. coli concentrations. Water hyacinth removed E. coli from shallow water by providing a surface (i.e., submerged roots) onto which pathogens sorbed and by protecting organisms that consume E. coli. Unfortunately, because of root association, the total E. coli load within the water column was greater with water hyacinth present, and results hinted that the plants’ protective environment also harbored parasites. The use of water hyacinth to keep surface water around floating communities low in E. coli could be beneficial as this is the water layer with which people most likely interact. Aquatic vegetation naturally proliferates in and around Claverito. While this study was based on curating aquatic plants in order to achieve a water-quality outcome, it nonetheless supports concrete actions for Claverito residents under non-curated conditions, which are outlined at the end of the manuscript.
