This is how it is pronounced in Pennsylvania and basically anywhere that isn't New York, New Jersey, Maryland, or the Deep South.Once in California I had to resort to Italian to make myself understood when asking for water, which Americans appear to pronounce as "wadder" , while we English say "warter" (if you're from the south) or "watter" (from t'north). At least, I think "acqua minerale" is Italian - it was close enough to "agua mineral" or whatever the Spanish actually is.
http://upload.wikimedia.org/wikipedia/commons/b/bd/En-us-water.ogg
Hmm, that clip doesn't play at all for some reason. Perhaps I don't have the right codec installed.
ETA: Now working, wtf. Anyway, it still sounds like "wadder" to me.