No they aren't. That's less than 1% of bottled water usage. Probably less than 0.1%.

I live in Alberta. We have among the strictest water quality standards in the world, far more stringent than bottled water. Yet every grocery store sells palettes of bottled water a week and there are entire service industries created around businesses purchasing bulk water for water coolers that are shipped around on trucks from far away distribution plants.

All of that can be replaced with a metal water bottle and our tap water.

And for the communities without access to clean drinking water, there are dozens of other solutions, of which 0.5 L plastic bottle water containers are among the worst.