Oral Rehydration Solution (ORS) is used to maintain proper fluid and electrolyte levels in the body. there are numerous commercially available preparations. But they often contain processed sugars, dyes, artificial sweeteners and preservatives. So if you want something better, for health or allergy reasons, I have made a few recipes for you. The first two recipes are balanced, containing the same carbohydrate, sodium, and potassium levels as commercially available toddler rehydration beverages. Additionally they provide magnesium and calcium which other options do not include. The third option provides less potassium. But its still provides some, along with magnesium and calcium. Each link includes both the recipe and a nutrient analysis.
Coconut water and Apple juice
(can omit the apple juice or substitute another clear fruit juice)
If you want a simpler option, you can use this sugar and salt recipe. However it is lacking potassium, magnesium, and calcium. It also includes a few additional options: http://rehydrate.org/solutions/homemade-ors.pdf