Yes, I tried to brew kvass. The results were not good. The product tasted like yeast. Here was my method:
1. I dried one pound rye bread in oven in a 200 degree oven. The rye bread came from a local bakery that I knew to not use preservatives.
2. I boiled about a gallon of water for at least 15 minutes to remove any biologicals and whatever chlorine that might have been present.
3. Poured the water over the bread and let the mixture sit covered for about 10 hours.
4. Filtered out the bread and added one cup of white sugar and one packet of bread yeast.
5. I let this mixture sit for about 10 hours covered in a dark closet.
6. I filtered again added about 2 tablespoons of raisins and let this mixture sit for five days in a dark closet.
The product was milky gold and fairly sweet. There was plenty of sediment, but I don't believe that all the yeast settled out. Anyway, that was my experience.