Jenn,

Anything over (I forget whether it's 10 ppm or a slightly higher number) has to be listed on the label.

There isn't any phosphoric acid in seltzer water, as there's nothing in it which needs either the flavor or the acid. All seltzer water consists of is carbonated water and a flavoring, usually an essential oil.

The web page you got that article from is full of holes, Catty. Scroll down to where it's talking about "average PH of the human body" or some other such nonsense. It gives a very definite value of 7.63, which screams BS. Given that there are areas in the human body with a very, very low PH, (stomach, intestines, liver), to have an average of 7.63 implies there are areas in the body which have a PH approaching 14, which is frankly lunacy.

Again, given that the average gastric acid PH is in the 1-2 range, and soda would actually RAISE that PH, (ph of 2.5-4), why would the stomach need to pump antacid into the stomach? That can of Coke you just drank RAISED the ph of your stomach(which would require additional acid to maintain the PH), not lowered it (which would require the antacid).