I assume you used tap water. Did you let the water boil for at least 15 minutes? Just bringing it to a boil is not enough. Anyway, I've never used tap water for my water kefir grains, always mineral water. Also, I've always used organic brown sugar, half a lemon, 2 dried figs and sometimes some egg shell (grains need minerals to grow like crazy). That is for 2 liters of water.