Naturally Cultured Sparkling Probiotic Water aka Water kefir (ke-feer) is a sparkling probiotic beverage. A non-dairy source of probiotic strains of lactobacilli, water kefir is an alternative to yoghurt kefir. Naturally fermented using a symbiotic culture of bacteria and yeasts, water kefir has a vanilla, creaming-soda like flavour with fewer than 45 calories per serve.