3 Toilets in home. 2 upstairs are American Standard Cadet's. One on main floor is different model of an American Standard. All started to do the following...they flush normally and completely, never require a 2nd flush. The water fills the bowl normally. Then within a short time the water level in bowl drops 3/4 to 1"...and usually holds that level, sometimes overnight it might drop just a tad more but nothing major. I have plunged all 3, augered all 3, no blockage. All other drains in house work perfectly and drain normally. Suspected maybe a partial blockage in vent pipe (wouldn't be totally blocked would it if everything else works fine?). Called 2 plumbers (reputable in this area) and they wouldn't even come look, advised cleaning the roof vent first. Vent is 3". I called Roto Rooter and another local drain company (Drain Master) and both advised that they do not get on 2nd story roof's. I asked if this was because of winter, and they both said no, they don't even do it in the summer. So here I am . Any advice?

A problem with the vents is such a remote possibility, that I would not even bother checking them.

partial main stoppage somewhere.

you mean a partial blockage between the toilet on the main level, on out to the street in the main drain...not the venting? Should have Roto clean out the drain in basement cleanout?

just fyi, if it makes any difference, there is only one vent pipe on roof.

Pour a 5 gallon bucket of water down the toilet....slow and steady.....does it back up?

all i can tell is the stoppage is somewhere downstream of where the 3 toilets join a common pipe..

What makes you say that packy? He didn't say anything about backing up. They flush fine, but lose a little water over time.

Water level drops in tank are usually caused by a faulty seal at the flapper valve. The only other cause would be leak by at the bolts that connect the tank to the bowl. Period.

One more... siphonage of tank water thru fill valve. But all three toilets simultaneously? A stretch.

He said the water level in the bowl.

"What makes you say that packy?"..
it just sounds to me like water is piling up in a drain and letting go overnight causing the bowls to syphon..
am i 100% sure about this guess?? not really..
am i 50% sure? well. maybe
yes or maybe no..
whether it is a blocked drain or a blocked vent, somebody with a snake has to get out there and poke it around.

Let me add a bit more, based on your suggestions. I poured additional water in one of the toilets, after it had filled and went down. Slowly but surely the water drained down to below it's normal fill level, didn't hold the additional water. Next, right next to each toilet is a sink/vanity. I pulled the trap off the sink (thought it might give additional vent?) and it did absolutely nothing, the water level still reduced after filling (tried it 3 or 4 times on each toilet). To clarify it I'm talking about the bowl water not the tank. There simply is no access to the vent other than the roof (I checked in attic, vent sticking up is right at edge of steep roof pitch, VERY hard for anyone to get in there and cut open, then repair, etc.) and right now no one will go on 2nd story roof especially in winter (me included, lol). Should I just cough up the bucks and have a drain company come and clean the main drain from the point where the three toilets join the stack which goes into the basement floor on out to street (there is a cleanout right at the point where they join)? This would eliminate the drain problem and focus on the vent?? I am no plumber but don't follow how a partially blocked drain would allow a good flush but then immediately cause the bowl water to go down...but I hope that's what it is .

so do i..
but if you removed the sink trap and the same thing happened then that would kind of eliminate a vent problem.
the reason i say to clean from the piont where all 3 toilets join is because all 3 toilets do the same thing.
maybe try this...
bail all the water out of one of the second floor toilet bowls so air can get into the drain thru the empty toilet. now flush the other toilet to see if anything different happens ?????

Do these toilets have bowl cleaner in the tanks?

nope no bowl cleaner in the tank. I'm gonna try Packy's idea (empty one on 2nd floor, see what happens) tomorrow and will let you guys know. Someone suggested to me that what is happening is that the bowls are actually overfilling a bit and then seeking their own level through the toilet trap and that I could tell by measuring the bottom of the highest point of trap and see if that equates to the water level..if so the level is fine. Let ya know tomorrow...thanks all.



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okay....totally removed all the water from bowl in one of 2nd floor toilets (made it bone dry). Went to other 2nd floor toilet gave it a flush. Did same thing, filled, went down 3/4 to 1". If anything..and very hard to tell even though I marked the water line before flushing, etc...might have went down a tad bid farther..but can't really say much, if any. Then I went an tried toilet on main floor...no change.

well, that ought to 100% eliminate the question of a blocked vent. the empty toilet bowl will act as a vent.
as for the overfilling theory ???
i can not imagine that a bowl will overfill as the tank is filling. the water level will reach a certain height and go no higher because any excess water entering the bowl will just overflow the internal trap.
yeah, i could see it coming up maybe a tiny bit (even that would be unusual) but never 1 inch..

well I guess i'll just have to live with it over time and see what happens, whatever is causing might get bad enough to present itself in other ways and then will know what it is. I called American Standard Tech support. There response was it is not uncommon for the toilet to overfill and then settle. When I questioned if that holds for up to 1" they said oh yes that is not unusual. I said wouldn't it just "run over" the top of the trap rather than overfill and they said once there is no pressure behind it and its just running over the top of the trap it takes 30 seconds or more to run down. I asked could they tell me, with some type of measurement like from top of bowl to top of water so I could measure and see if mine were within the norm, and they could not. Oh well.

Thought you all would enjoy hearing what I received from American Standard. I emailed their technical support team about my problem. They asked me to give them some information (the stamped/engraved numbers inside the toilet tank). I did so. They replied that for all 3 of the models, I should take a ruler and hold in inside the bowl and get a measurement from top of the rim (the part that the toilet seat rests on) down to the top of the water line (which they referred to as the model spot). All is okay if the level is between 5 1/2" and 6" on a calm day (they pointed out that wind and some seasonal pressure changes would make the number vary a bit). The further said it is not unusual for the toilet to overfill at first then settle to this range of 5 /12 to 6. Mine measured 5 1/2.