Both kombucha and water kefir are sweet-sour, slightly, bubbly drinks. They’re both full of probiotics and they’re both made by yeast and bacteria to ferment a probiotic beverage.
The SCOBY (Symbiotic Colony Of Bacteria and Yeast) is used to make kombucha. Water kefir grains are also colonies of bacteria and yeast in cellulose, but they tend to grow like grains, not in one large mass. They float in liquid rather than always rising to the top
One big difference between water kefir and kombucha is the length of time it takes to brew a batch. The SCOBY will take between 7 and 30 days to finish fermenting the liquid, or an average of about two weeks. The water kefir grains, on the other hand, only take about three days to ferment the probiotic rich beverage.
Unlike kombucha, water kefir is caffeine free. A lot of people find that water kefir has a more mild, pleasant flavour.