Step-by-Step Guide

1. Toast the Bread Slice the rye bread and toast it in the oven at 350°F (175°C) until it’s dark brown but not burnt. This gives the kvass its deep, malty flavor.
2. Make the Mash Boil 10 cups of water. Put the toasted bread in a large glass or ceramic container (avoid plastic). Pour the hot water over the bread and let it sit, covered, for 4-6 hours or until the water is dark and infused.
3. Strain & Ferment Strain out the bread using cheesecloth or a fine strainer. Add the sugar and stir until it dissolves. Let the liquid cool to lukewarm (~100°F or 38°C).
4. Add Yeast & Secondary Fermentation Dissolve the yeast in a bit of warm water, then add it to the liquid. Optionally, add a handful of raisins (they will rise to the top when fermentation is done). Cover loosely (use a towel or a lid, but don't seal it airtight). Leave it at room temperature for 12-24 hours—the longer, the stronger the flavor.
5. Bottle & Carbonate Strain again and pour into clean bottles. If you want carbonation, add a teaspoon of sugar per bottle before sealing them tightly. Store in the fridge for another 2-3 days to build fizz.
6. Enjoy! Chill and serve! Kvass should be slightly sweet, tangy, and mildly fizzy. Pro Tips for Apartment Brewing Use flip-top glass bottles for carbonation (plastic can explode under pressure). Store kvass in the fridge once it's done fermenting to stop it from getting too sour. If you want a less sweet drink, let it ferment longer before bottling. Add flavors like honey, mint, ginger, or berries for variations.