Reciently one of our second floor toilets has begun losing water from the bowl. When it is flushed, it fills to the proper level and shortly after refilling the tank, all is silent. There is no apparent leakage and the water level may stay up for quite some time. However, it seems that after the first floor toilet is flushed several times, the water in this second floor toilet bowl will be low. The other second floor toilet is unaffected and the water in the bowl losing water never gets low enough to expose the trap, so, we don't have an issue with sewer gas backing up into the room.

It seemed to me that this might be due to a blockage in the vent pipe. So, I went up on the roof and ran the hose down the vent full blast. The water ran freely with no sign of backing up even after several minutes of running, yet, the toilet still exhibits this problem of losing water.

Any suggestions on how to fix this?

Hi Jimmy,

Are you quite sure you checked the right vent? Tell you whot! Go down and flush the first floor toilet a few times while someone watches the toilet that loses water. Does the water level fluctuate when the down stairs toilet's flushed? If so I don't care how many vents you checked you missed the one that's blocked. Look in the attic over the bathroom and see if the vent pipe revents back into another vent before it exits out the roof. A revent is more difficult to snake because it's connected to the vent that terminates on the roof. You'll have to cut into the proper vent, snake the line and then couple it back together the way it was. If your handy and when you have the vent apart now would be a good time to add a clean out tee to the vent before you couple it back. That way you won't have the hassle of cutting the line if you have to snake in the future. Good luck, Tom

Thanks Speedball. There are only two vent pipes coming out the roof and I ran water down both - however - it is quite likely that they branch, so, I guess I'll be getting up in the attic, cutting some pipes and snaking it out as you suggest.