Kohler Toilet Issue

My second floor has two bathrooms side by side. The arrangement is sink, toilet, bathtub, separating wall, then bathtub, toilet, sink. The toilets get plugged once in awhile (especially when there is a big load and twice both toilets got plugged at the same time, when I plunged one out, the other one drained out also. Recently, I noticed that when someone is showering in the first bathtub, the drain in the second bathtub makes a gurgling sound. The other day when I flushed the toilet the bathtub gurgled again.

The only thing I can add is that I believe the vent is between the two bathtubs. And most of the time when the toilets plug up there is only water in the bowl.

Any ideas on what the issue is here?? BTW I have asked a couple of plumbers about this already and they both seemed confused.

Sounds to me like you have a partially obstructed drain line...might be time to get it cleaned out.

Thanks for the recommendation.

What worries me though is if it's not blocked when they come out, how do they know where to look, or how do I know they fixed anything. Do plumbers have video now as that would confirm if there was a partial blockage right?.

THere are cameras that can be put down the line. Basically, if you have a 4" drain line, you need a 4" cutter head to clean the whole diameter of the line. If you use anything smaller than that, you will miss things and may just punch a hole through the obstruction which may let liquids pass, but will quickly reblock when solids are present. Run the snake all the way to the main sewer at the nominal diameter, and a good operator can locate roots and other problems. Dealing with a long, large diameter snake is an aquired skill, and can be dangerous if you don't have experience. A camera could find a belly, or dip in the line, or a collapsed section more easily, if it existed, but runnign the snake the full distance at the proper diameter is the first step.

I've got a plumber coming in this week as part a kitchen remodel, so I'll ask him if he can do this for me.

BTW the two toilets did the double plug up again yesterday, first one filled up to the rim and so I flushed the other, it filled up to the rim too for a few seconds, then they both quickly drained out together along with the gurgling noise from the bathtub.