KeVita Apple Cider Vinegar Tonic is low-calorie, with a sweet and tangy apple cider taste and fermented with water kefirWater kefir is a lightly effervescent water based drink that is made by fermenting kefir culture grains in water with sugar. Water kefir grains do not contain grains such as wheat, they are a unique culture. Cultures that are used to ferment dairy kefir are a different strain. Fermented water kefir is the base of all of KeVita’s Sparkling Probiotic Drinks and Apple Cider Vinegar Tonics. culture. Tonics contain 2 tablespoons of apple cider vinegar and billions of live probiotics per bottle.