Yesterday my wife noticed that one of our toilets was bubbling whenever she used the washing machine. They are on the same line with the toilet about 12' before the washing machine. I went under the house (crawlspace) and using the clean out close to the toilet and I used a 50' 1/2 inch snake. The toilet to the main line out to the street is about 20 ft. I hit nothing.

Now when we used the tub in the other bath the same toilet is bubbling. The tub is on another line that links up about 10'before it heads out to the street. I have no clue what is going on. l'd love to hear some more ideas.

I had the same problem w/my septic. Its your drain line outside the house. If you have a septic tank it could be full or your field lines have roots or something else clogging the line.

You have a partial clog. You just haven't hit it yet. Take the lid off the cleanout and flush a toilet. Does the water back up? Let me know. Tom