That depends entirely on how you define your sobriety. If sobriety means consuming no alcohol, including trace amounts found that naturally occur in products like vanilla extract or fermented foods and beverages, then yes, kombucha breaks sobriety. That is because it has trace amounts of alcohol in it due to the fermentation process. However, kombucha cannot get you drunk, and, for most people, there are no noticeable effects from the small percentage of naturally occurring alcohol in these beverages. If breaking sobriety is defined as drinking an alcoholic beverage or getting drunk, kombucha does not qualify.