Water Kefir is a delicious fermented drink that is made with a simple sugar-water solution and water kefir grains. Water kefir is rich in probiotics and after the fermentation period, is low in sugar. The taste is tangy and mildly sweet, but it can be flavored in any way with juice, fruit and herbs. Water kefir is often compared to kombucha, but unlike kombucha it is caffeine-free and has a more mild taste.