I've seen other water brands that say on the label that its municipal water from whatever small town they built the bottling plant in, its not unique to Dasani.

Big companies like Coke have multiple bottling plants so the quality will vary depending on which plant it came from and how good their local water treatment facilities are.

I know in the town I lived in at the time I would regularly get letters from the water company saying they were legally obligated to advise all customers that they had failed their water quality test from the government (again) and here's a list of all the contamination found in their water but they promise its still totally safe to drink, the levels of contamination in the water are just a little bit over the legal limits.