Kvass is a fermented beverage made from black or regular rye bread. The colour of the bread used contributes to the colour of the resulting drink. It is classified as a non-alcoholic drink by Russian standards, as the alcohol content from fermentation is typically less than 1.2%. Overall, the alcohol content is low (0.05% - 1.0%).

The sign on the side of the tank reads "Kvas Ukrainski" and I still have to "decipher" the brand name...