A slight amount of water leakage is normal (about 1-2 mm) but if you see a lot of water, something's wrong. First, always make sure the konnyaku powder fully dissolves in the boiling water- I have detailed instructions on how to do this in my recipe card. Second, check the amount of sugar added. Too much sugar is not just bad for one's health, it's bad for the jelly and may turn it back into liquid.