Bring the water and stevia to a simmer. Stir so that stevia dissolves completely. Then let it cool to room temperature. Place the raspberries in your Vitamix and process until smooth.
Strain the raspberries through a fine-mesh strainer over a bowl. Then mix with the sweetened water and stir well.
Next squeeze the juice from the lemons. Combine fresh lemon juice and raspberry syrup. Slowly add sparkling bottled water.