lower calorie homemade lemonade

This lemonade tastes great and isn't too full of sugar.

    -4 Lemons

    -1/3 cup sugar

    -1/3 cup stevia extract

    - About 2 quarts of water , I taste test to perfect.

I don't know how common stevia extract is I picked it up at our local grocery store awhile ago, when I looked last time I was there they didn't have it.