Since chameleons assimilate calcium through the foods they eat and not from the pure water they drink, I would say that the odds of them ingesting enough calcium through the water to be enough are slim. As Kinyonga said, calcium can be overdone as is overdone by many as standard practice, imo. I am a subscriber to the less is more approach to all supplements and don't believe it is natural or healthy to dust feeders with powdered calcium with every feeding. 3-4 days a week is the maximum I supplement most any animal, unless there circumstances that warrant deviating from this.
Bottled water is not a great idea. Bottled water is often enhanced with various minerals, salt, and fluoride for taste and health. Use distilled or reverse osmosis water instead.