What is this? It's sodium right?
These water bottles I've been chugging down daily also have:
ingredients: Purified water, Potassium Bicarbonate, Sodium Bicarbonate, Cacium Citrate, Sodium Chloride, and Magnesium Oxide.
I just noticed these ingredients this morning in my class!
So there is sodium in these water bottles?? Can this affect me??
I think several brands of mineral water contain dietary-significant amounts of sodium. It's a consequence of the rock types that the water passes through on the way to a spring and its retention time underground. Moderate amounts of sodium are to be expected as rocks containing sodium are very common.
Mineral waters should list the quantity of each element per litre (at least they do in Europe). Most will be low enough not to cause concern (eg. Evian is only about 5mg/L).
I'm not sure what the regulations are in the US. It's odd that your water lists solid ingredients like that - almost as though it is tap water that has been distilled and then re-mineralised.
Tap water in most UK and US area's should be perfectly safe to drink but may contain trace amounts of pesticides in some areas. You should be able to get a full breakdown of your tap water's mineralogy and pathology on request from your provider or local authority. It's worth noting that some tap waters can also contain dietary-significant amounts of certain elements, so if you're really concerned about your mineral intake you should figure this in to your calculations.
This paper might be of interest - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1495189/