Disappearing Water

[jarumal]

We've recently purchased and had installed three Drake G-max toilets. The two upstairs work great, but the one on the main floor is causing us a little worry. After about 8 hours, the water in the bowl almost completely disappears. The water in the tank though remains at the proper level. We asked the plumber about this and he said we suffered from toilet obsession. When pushed he said he had no clue and that the bowl is probably defective and to get a new one.

We brought the bowl back and installed ourselves the new bowl with the previously purchased tank. We had hoped this would solve the problem, but the same thing is happening. The old Kohler had never done this in this bathroom and the other new toilets upstairs work fine. What could be the problem?

[jimbo]

Since you have pretty much ruled out a cracked bowl, by replaceing it, the next thing that comes to mind is a blocked vent. If the vent for that toilet is blocked, it would probably flush OK, but the bowl can be siphoned by water from upstairs flush passing by the toilet downstairs.