The water level in the bowl is determined by the built in trap in the back of the bowl. Water is allowed to enter the toilet and it then "over flows" the p trap in the back when flushed. Once it's flowing, it syphons the water out of the bowl. While the tank is re-filling, a small portion of water should be running down the overflow from the small hose clamped onto the overflow This rinses the inside of the bowl, as well as helps-refill the bowl. Be sure that hose is directed inside the overflow tube. To see what the max water level in the bowl can be, add some water from a cup or glass. Once it's full you can keep adding and it won't get any higher. This will be the max level you can expect.