A Stepped Wedge, Cluster-randomized Impact Evaluation of a Household UV-treatment and Safe Storage Drinking Water Intervention in Rural Baja California Sur, Mexico

Twenty-five to thirty communities (400-600 households) have been identified by Fundacion Cantaro Azul (FCA) as communities that are appropriate for their safe water program. These communities were identified based on their sources of water (chemical and taste characteristics) and resource availability (access to electricity and lack of access to piped water). Fundacion Cantaro Azul is planning to expand their safe-drinking water programs to all 600 households in these communities. In order to allow for a meaningful evaluation of the impact of their program the organization has agreed to randomize the timing of implementation of the safe drinking-water program to eligible communities. This will allow independent researchers (the lead investigator and key personal in this protocol) to make household visits during the implementation of the programs and will further allow for a valid evaluation of the programs' impact using a stepped wedge study design. Through the stepped-wedge study design all communities, over a 12-15 month, period will be approached by Fundacion Cantaro Azul for promotional meetings; since no community will have received the intervention they will be acting as their own controls until the time they are approached by the organization. Randomizing the time at which a community is approached reduces bias and allows for meaningful evaluation of differences in outcomes due to the safe drinking-water program. As part of this study design a randomly assigned, predetermined number of rural BCS communities will be approached every two-months for enrollment in the safe water program by Fundacion Cantaro Azul, and thus 'cross-over' from the comparison group to the safe-water group. Within each of these crossover groups half of the clusters will receive a "Basic" program variation, and half will receive an "Enhance" program variation. This process will continue until all consenting households in the 25-30 communities have received a UV disinfection system, and related support through the safe drinking-water program. Field teams, trained and supervised by the lead investigator and key personal listed in this protocol, will conduct independent (from Fundacion Cantaro Azul) household visits to collect data on the outcomes of interest. During household visits structured interviews and water-quality sampling will be used to measure these outcomes (prevalence of gastrointestinal events, concentrations of E.coli in household drinking-water, school and work absenteeism and compliance with the disinfection strategy.) The stepped-wedge design will allow for evaluation of the impacts of the safe drinking-water programs while allowing the relatively small organization to manage the logistics of installing 600 household disinfection systems, in a manner consistent with their mission, commitments to regional governmental collaborators, and fiscal restraints.