I've mixed an inexpensive EGR for use during hot pistol matches the last couple of years that is titrated for 1/2 liter bottles of water....while I've vacuum sealed some pouches for my remain overnight bag, it is more convenient to just repurpose pill vials, and throw them in with the water to be mixed as needed.. I alternate EGR to water, depending on how I feel

1/8 teaspoon Morton's lite salt ... about 1/2 potassium chloride and 1/2 sodium chloride

1/8 teaspoon Morton's regular salt... sodium chloride

3 teaspoon (one tablespoon) sugar... the sugar helps the absorption of potassium and sodium