I'll assume that every ounce of bottled water or soft drink replaces water that people would have drank anyway, and possibly with more efficiency - a larger percentage of the (expensive) bottled water gets used on the unalienable human need to drink than if the same water was piped to houses and used for both drinking and washing.

The plants may be blamed for transferring water scarcity from places where the drinks are bought and drunk to the places where the bottling plants are operated, but not for creating water scarcity.