Need to use up excess whey? Here's an easy recipe for homemade soda… (It calls for 1 cup of whey!)
Put the sugar in a gallon jar.
Add warm or hot water, just enough to dissolve the sugar when stirring.
Combine the lemon juice and cool water to fill the jar to the shoulder (3/4 full).
Add the whey. Stir.
Cover tightly and let culture at room temperature for 2 to 3 days.
Transfer to fridge or decant to Grolsch-style bottles and chill. If it's too tart, add honey or stevia, to taste.