Recipe inspired by Kathryn Kingsbury's, at http://www.herbcompanion.com/recipes/08_09_05-parsley
You may also want to check out mediaphage's Ginger Ale recipe:
2-Liter Soda Bottle & Cap (clean it well with soap, or a diluted bleach solution)
1 to 2 cups Sugar
Juice of 2 Limes
Yeast (common baker's yeast will work, but wine or champagne yeast is recommended)
1 bunch of fresh parsley
Step 1: Parsley Water
Meanwhile, juice the 2 limes. You can boil lime zest along with the parsley if you would like.
Step 2: Strain and cool
Step 3: Filter
Step 4: Mix, bottle, and shake
Leave bottle to sit for a day or two until pressure has built up to the point that the bottle does not indent when you squeeze it. Put it in the refrigerator to stop the fermentation. If you let it sit too long, the bottle will explode.