Make sure your whey is strained well through a fine mesh strainer, or cheese cloth
Combine the sugar, lemon juice, whey, and filtered water into a glass jar, jug or bowl. I used a gallon-sized jar.
Stir thoroughly until the sugar is mostly dissolved.
Once combined, use your funnel to add the lemonade mixture to your swing top bottles, (can also use mason jars here, if they seal well).
Leave the jars on the counter to ferment for 2-7 days, until they carbonate.
During the fermentation period, burp and mix the jars once per day. To do this simply open the top to release pressure. You’ll notice it getting more and more carbonated every day. Once you close the lid gently, tip the jar over 3-4 times to keep mixture combined.
Check them daily because the fermentation time can vary a lot, they will explode if left alone for too long.
Store your lemonade in a sealed container in the refrigerator. Serve cold from the fridge or over ice and enjoy!
*If you see a white film on top of your drinks at any point, don't worry. It's kahm yeast from the fermentation process, gently tip your jars over to re-incorporate is (use caution as they start to carbonate.)