Generally the rice on top will cook first and the bottom later. If you put too much water in, it will stick. I can't say how much, I guess you should put the amount of water in about 6 or 7 centimeters above the rice, and then based on your experience, if the rice will still be sticky and the water will still be too much, then it will be less then 1 or 2 centimeters, and then after it is cooked, then smother it for about 20 minutes. The rice will cook underneath that way as well, it's not used in rice cooker's that big. When in that large amount of cases, do not hesitate to try with steaming, and delicious.