OK they didn't call it that, but I found this a while back and it would work quite well. Take some 1 quart barley water. (Water that barley has been boiled in.) 1/4 cup vinegar or lemon juice and a tablespoon of molasses and a tablespoon of salt. Ok, it might not taste as good as yer favorite fruit flavored wonder drink, but it would do the same thing.
BTW Mollasses has 300-350 mg potassium per table spoon.