A senior researcher and hospital Chief of General Pediatrics, testifies about his work with a California school district to prevent obesity by developing a middle school program to promote healthy eating and physical activity. A two-year study has found that students have limited access to drinking water, especially at meals. In the schools being studied, water is neither sold nor provided for free in cafeterias. There are no water jugs or faucets with cup dispensers. Water fountains are too few to meet mealtime needs. Vending machines quickly run out of bottled water. The study explored providing filtered tap water in jugs at one school. Students drink it at lunch, and PE teachers borrow the jugs because their students have limited access to water. With 1 in 3 California children reported to be overweight, the researcher points out that water is healthy and has no calories, and that assuring its ready availability in schools should help prevent childhood obesity. (Contains 2 footnotes.)