In a large pitcher, mix 1 liter of cold water with 100 grams of sugar until the sugar is dissolved.
Add 100 ml of your preferred fruit juice or fruit syrup (such as lemon, orange, or mango) to the sugar-water mixture and stir well.
In a separate container, dissolve 1/4 teaspoon of baking soda in 50 ml of water.
Slowly pour the baking soda solution into the fruit juice mixture while stirring continuously. This will create fizz in the drink.
Pour the homemade soft drink into glasses filled with ice and serve immediately.