Delivering biologically safe stored water in low-resource settings using in-situ electrochemical activation

Stored water, such as rain- or ground water, can be a lifeline to people who do not have access to reliable freshwater sources, but can deteriorate without proper maintenance, increasing contaminant concentration. The principal aim of this study was to investigate the antimicrobial efficacy of a prototype small-scale in situ electrochemical activation [ECA] cell to reduce bacterial loads present in stored water tanks for applications in low-resource settings. Feasibility trials (UK and Madagascar (20 L tank)) demonstrated zero coliforms recovered after a 30-min ECA treatment period. Dynamic proof-of-concept trials (UK (100 L tank) demonstrated that coliform-free water could be produced from rainwater using the prototype ECA cell, but ECA treatment time was dependant on initial microbial loading. An international deployment trail (India) also resulted in biologically safe water (coliform free) when stored freshwaters were treated by the prototype ECA cell, whereby there was an absence of coliforms in the ECA treated water but was present in eight out of eleven samples taken in the untreated groundwater source over a six-month period. The main novelty of this study is the demonstration of the antimicrobial efficacy of a prototype in situ ECA system that uses only natural ions present in stored freshwaters to produce oxidative and reductive antimicrobial species to produce biologically safe water. Ultimately this study demonstrated that a small-scale in situ ECA unit can improve the quality of stored freshwater sources to help mitigate preventable waterborne diseases through the reduction of indicator pathogenic species (e.g., coliforms).