Potassium can be as bad as salt if you're intake is too high. Potassium and sodium are pals, you need potassium to balance sodium, and in turn calcium and magnesium. I am always being nagged about low sodium levels because I don't like salt (except olives for which I have no explanation!). When I was veggie I was constantly being shouted at for at times dangerously low sodium, when admitted to hospital my sodium levels were on the floor but then when my potassium levels plummeted because of the rapid insulin infusion my sodium levels went through the roof (for me at any rate), everything swelled up and I had normal blood pressure (I'm usually low). The consultant confirmed it's because you need potassium to metabolise salt otherwise it stays in your bloodstream which is the place you don't want it. Potassium went up and hey presto low sodium, no fluid retention and low blood pressure. Too much potassium can cause heart problems though so it's a complex business! We do need a lot more potassium than sodium though so it's harder to get too much.
Oh and bottled water can have huge amounts of sodium if you drink a lot!