A cluster-randomized controlled trial of an elementary school drinking water access and promotion intervention: Rationale, study design, and protocol.

introductionPromoting water consumption among children in schools is a promising intervention to reduce sugar-sweetened beverage (SSB) intake and achieve healthful weight. To date, no studies in the United States have examined how a school-based water access and promotion intervention affects students' beverage and food intake both in and out of school and weight gain over time. The Water First trial is intended to evaluate these interventions.

methodsInformed by the PRECEDE-PROCEED model and Social Cognitive Theory, the Water First intervention includes: 1) installation of lead-free water stations in cafeterias, physical activity spaces, and high-traffic common areas in lower-income public elementary schools, 2) provision of cups/reusable water bottles for students, and 3) a 6-month healthy beverage education campaign. A five year-long cluster randomized controlled trial of 26 low-income public elementary schools in the San Francisco Bay Area is examining how Water First impacts students' consumption of water, caloric intake from foods and beverages, and BMI z-score and overweight/obesity prevalence, from baseline to 7 months and 15 months after the start of the study. Intervention impact on outcomes will be examined using a difference-in-differences approach with mixed-effects regression accounting for the clustering of students in schools and classrooms. DISCUSSION: This paper describes the rationale, study design, and protocol for the Water First study. If the intervention is effective, findings will inform best practices for implementing school water policies, as well as the development of more expansive policies and programs to promote and improve access to drinking water in schools.