Morton Lite Salt and Vitalyte.
(This is a tangent to other low-salt discussions on TFL.
I came to Morton Lite Salt via Vitalyte, which used to be known as Gookinaid, and before that "E-R-G" which stood for "Electrolyte Replacement, with Glucose."
https://vitalyte.com makes a great isotonic sports drink. Nutrition info here:
When mixed according to directions, Vitalyte has, per 8 fluid ounces:
67.5 mg sodium. ( 2.93 mEq.)
96.5 mg potassium. ( 2.47 mEq.)
11 grams carbohydrates, of which 10.5 are sugar.
I'm cheap and wanted a less-expensive DIY version for my hydration/sports drink, that also has less calories.
I discovered that Morton Lite salt, a combination of sodium chloride (regular salt) and potassium chloride, is close to the isotonic Vitalyte in the amount of sodium and potassium.
From the Morton Lite Salt label, it has, per 1/4 tsp:
290 mg sodium.
350 mg potassium.
I dissolve 1/4 tsp in 1 liter of water. 1 liter is 33.8 fluid ounces.
Using a 1/8 tsp measuring spoon makes it convenient to mix in a 1/2 liter bottle of water.
Mixed this way, Morton Lite Salt has:
290 / 33.8 = 8.58 mg sodium per fl oz.
350 / 33.8 = 10.35 mg potassium per fl oz.
Multiply by 8:
8.58 * 8 = 68.6 mg sodium per 8 fluid ounces. ( 2.98 mEq.)
10.35 * 8 = 82.8 mg potassium per 8 fluid ounces. ( 2.12 mEq.)
The MLS container has 311 grams of product, and the label says there are 222 servings of 1/4 tsp per container. That would be enough for 444 half-liter bottles. Using Kroger's price of $2.99 per container, that would be .67 cents, yes, only 2/3rds of a cent, per half-liter bottle of water.
Granted, that does not include sugar or flavoring.
It's not an exact substitute, but Morton Lite Salt is available at a very reasonable price at Kroger and Walmart.
Sweeten and flavor according to your taste and calorie needs.
To get Vitalyte's amount of calories per 1/2 liter, add two tbsp of regular table sugar, 22 grams to be exact, to get 88 calories. However, be advised that Vitalyte uses mostly glucose, and a little fructose, not table sugar (table sugar=sucrose). Glucose, in the form of dextrose, a.k.a. corn sugar, can be obtained from beer brewing supply stores.
Vitalyte has a small amount of magnesium and calcium. So if you want to get more exact, you could add those too, but the amount is miniscule - insignificant compared to the sodium and potassium. I'll leave the calculations to you.
mEq, milli-equivalent, calculator: http://www.nafwa.org/convert1.php