Make a "wort" for your ginger ale by placing 3 cups of the water, minced ginger root, sugar, molasses if needed, and salt in a saucepan and bringing to a boil.
Simmer the mixture for about five minutes until sugar is dissolved and mixture starts to smell like ginger.
Remove from heat and add additional water. This should cool it but if not, allow it to cool to room temperature before moving to the next step.
Add fresh lemon or lime juice and ginger bug or whey.
Transfer to a 2 quart glass mason jar with an air-tight lid. Stir well and put lid on.
Leave on the counter for 2-3 days until carbonated. Watch this step carefully. Using whey will cause it to ferment more quickly. It should be bubble and should "hiss" like a soda when the lid is removed. This is very temperature dependent and the mixture may need to be burped or stirred during this fermentation time on the counter.
Transfer to refrigerator where it will last indefinitely.
Strain before drinking.
As with any traditional fermented drink, this is more of an art than a science. The outcome depends greatly on the strength of your culture, the temperature of your house, and the sugar used. The final mixture should smell of ginger and slightly of yeast/fermentation and should be fizzy. Watch carefully that it doesn't become too carbonated as this will cause too much pressure and may result in an exploding jar! The mixture can be strained and transferred to Grolsch style bottles before putting in the refrigerator.