Water Fountains in Schools - More Powerful than a Sugar Tax?

Could the provision of powerful water fountains in schools and colleges be a more effective and fairer nudge to encourage students to drink more water and avoid sugary products? Evidence in this article published by Salon finds that in schools where fountains were widely available, the body mass index of students was lower than in those where water fountains were absent. "Taking a drink from a water fountain is a piece of (calorie-free) cake."