I have a shower, toilet and sink in lower level and my kitchen sink on main level that use the same drain. About 6 months ago the toilet started to bubble when used the shower. Later, water etc (was not coming from toilet) came up through shower drain. Anytime used bathroom sink or shower or kitchen sink for any length of time, would always back up through shower stall. 2 plumbers have roto rootered out and works GREAT for a while. Septic pumped 6 months ago so not problem. Can it be something with vent in attic? House was built 30 years ago - what would cause vent to be bad? Thanks

About 6 months ago the toilet started to bubble when used the shower. Do you see bubbles or hear a gurgle? This is important for me to know as bubbles indicate a partial blockage while gurgles indicate a blocked vent. Back to you. Tom

Tom.
The toilet bubbles. But 2 plumbers have roto rootered extensively and we ran water from ALL drains attached for almost an hour after - it was Great. All was well for about 2 weeks. Then, when I emptied dishwater (no dishwasher) I noticed the kitchen drain was slow after emptying 1/2. Went downstairs and toilet was bubbling. At that time did not see anything coming up drain in shower - where it usually does. So I ran water for about 10 minutes and still nothing. However, few days later, my son used toilet (very seldom used) all went down, nothing came back up but toilet kept overflowing. Nothing coming up in shower! Few days later I washed dishes and when it slowed down, I went downstairs and turned on faucet in sink. Water came up in drain. Have been watching shower drain for signs of water from upstairs sink (usually residue from grease etc.) Nothing was there until yesterday. All came up in shower! It does drain back down in a matter of minutes.

Your plumbers still haven't repaired the partial blockage. Where did they snake from? Cleanouts? Roof vents? You could have a break in the line that clears when snaked but begins to build back up as soon as you use it. That would explain why it drained fro awhile. I would get a company that has an "Sewer Cam" and take a look. Let me know what they find. Good luck, Tom