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How to Make Bread Kvass
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5 from 1 vote

How to Make Bread Kvass

Making bread kvass is a great way to use up leftover sourdough bread. It has a light, fizzy taste that's super refreshing. And since it's naturally fermented, it's a great source of probiotics!
Prep Time10 mins
Cook Time30 mins
Total Time40 mins
Course: Beverage
Cuisine: European
Keyword: bread, drink, fermented, fermented beverage, fermented drink, kvass, probiotics, Sourdough
Servings: 3 L


  • 1 lb sourdough bread sliced (stale is fine)
  • 3 L water
  • 1 cup sugar
  • ¼ cup honey
  • 1 tablespoon sourdough starter
  • sprig of mint (optional for flavor)
  • 2 2 L plastic pop or juice bottles thoroughly cleaned


  • Heat oven to 350°F. Place bread slices on a wire rack set on top of a baking sheet. Bake until completely dry and dark brown (but not black), flipping slices occasionally. Baking time will depend on the moisture content of your bread.
  • Boil water using a kettle or pot. Place bread in a large heat proof bowl. Pour boiling water over bread, just to cover. After half and hour, add more water as needed to cover bread as the bread will absorb some of the water. Let bread steep in water overnight.
  • Line a wire mesh strainer with 2 layers of cheesecloth. Pour bread mixture through strainer into a pitcher. Add additional warm (not hot) water to come to 3L. Stir in sugar, honey and sourdough starter, add the mint. Let sit, lightly covered, in a warm spot until a slight foam forms on the top, 8-12 hours.
  • Strain mixture through 2 layers of cheesecloth again and pour into plastic or glass swing-top bottles, being careful not to fill each bottle more than ⅔ full. Place bottles into fridge and ferment for 2-3 days. Check bottles occasionally for pressure. If they feel very firm, loosen lid slightly to relieve pressure then reclose.
  • Kvass is ready to drink after 2-3 days, but it will continue to ferment after that. The longer it is allowed to ferment, the more carbonated and alcoholic it will become, but will still only be lightly alcoholic (maybe 0.5-2%). You can keep it in the fridge for up to a month.