Effectiveness of a School Drinking Water Promotion and Access Program for Overweight Prevention

Background and objective: Drinking water promotion and access shows promise for preventing weight gain. This study evaluated the impact of Water First, a school-based water promotion and access intervention on changes in overweight.

Methods: Low-income, ethnically diverse elementary schools in California's Bay Area were cluster-randomized to intervention and control groups. Water First includes classroom lessons, water stations, and schoolwide water promotion over 1 school year. The primary outcome was overweight prevalence (BMI-for-age-and-sex ≥85th percentile). Students (n = 1249) in 56 fourth-grade classes in 18 schools (9 intervention, 9 control) from 2016 to 2019 participated in evaluation at baseline, 7, and 15 months. Data collection was interrupted in 8 additional recruited schools because of coronavirus disease 2019.

Results: Of 1262 students from 18 schools, 1249 (47.4% girls; mean [SD] age, 9.6 [0.4] years; 63.4% Hispanic) were recruited. From baseline to 7 months, there was no significant difference in changes in overweight prevalence in intervention schools (-0.2%) compared to control schools (-0.4%) (adjusted ratio of odds ratios [ORs]: 0.7 [confidence interval (CI): 0.2-2.9] P = 0.68). From baseline to 15-months, increases in overweight prevalence were significantly greater in control schools (3.7%) compared to intervention schools (0.5%). At 15 months, intervention students had a significantly lower change in overweight prevalence (adjusted ratio of ORs: 0.1 [CI: 0.03-0.7] P = .017) compared to control students. There were no intervention effects for obesity prevalence.

Conclusions: Water First prevented increases in the prevalence of overweight, but not obesity, in elementary school students.