I can understand the position of the school on that matter. Flavoured water contains added ingredients which most of the time has artificial sugars in them. Some of these ingredients can cause health risk to children and I'm sure that aside, they do not want it to be a frequent occurrence at school. Given the condition that children refuse to drink plain water at all, I think it should be made an exception since refusing these kids because of impending danger can cause another risk like when they had to hospitalize a child. It means the cause has been defeated. Parents on the otherhand should try to encourage their kids and make healthier choices for them. The exposure to sugar is a cumulative long term effect that can be avoided.