I make this a lot to help with electrolytes:
1 pack unsweetened Koolaid
1/2 t light salt (sodium/potassium)
1/2 t vitamin C powder
1/2 t stevia
Enough water to make 64 oz
An alternative that doesn’t use the fake coloring that’s in koolaid would be to use lemon juice, but that would be higher in carbs.