Sewer backup mystery

[mattj]

I own a condo with a walkout basement built in 1979. The waste stack is shared with one other resident. There have been 3 sewer backups since I purchased the home in November, 2021. The most recent was this week. The condo association sent a plumber who rodded and cameraed the line. They told me there was evidence of wipes in the line but did not confirm whether there was an a actual blockage. Here is the mystery...with previous backups nothing was found in the line when rodded or cameraed. I had the line cameraed myself after a backup in November and was told that the cast-iron and pvc line where in good shape and nothing was in the line. I have not moved in yet and my unit has been empty . I spoke with my upstairs neighbor and she said she the only thing she flushes is TP and knows better (I believe her). I've gotten conflicting and dishonest responses from the condo association regarding the history of the backups prior to my closing on the unit (They said they have no evidence of previous backups when documentation and a conversation with the person who lived here before proves there was). There are some problems with the shower drain/pan but would that cause thick black smelly sewage to come backwards into the house? Rain run off does not go into the sewer so heavy rain is not the issue. What might be the cause, and how might I get to the bottom of this? I really appreciate any expertise and advice you might be able to provide.

 

[Twowaxhack]

There’s nothing much you can do if camera inspection doesn’t reveal the cause.

You could start mapping where the blockage is happening then camera that area again looking really close or even dig that area up if it repeatedly gets obstructed in the same area.

 

[RickFlorida]

I live in Florida and have a lot of experience with my older family members living in condos dealing with some things like this. It's one of the only things I don't like about condos is that you often share drain lines. Here in Florida, the condos sharing drain lines is more often a AC condensation backup in those drainlines that more often is the cause of problems/damage. With even just 3 story condos and having 2 units above the first floor unit, you now have the first floor unit being at the mercy of the above two units keeping their AC drain line cleared. If someone wants to service the AC drain line, they can't properly clean out the whole drain line of all 3 units unless he has has access to all 3 units at the same time. Needless to say, the bottom floor units often get flooded closets because the shared drain line was backed up above them. The only solution to these kind of problems I know of is always, always know people that already live there and talk to them about how much maintenance is done and how fast problems are fixed. Like 3 years of research before you buy a condo is the only way to know things like "do they share the AC drain line, do they pressure wash the walkways every other month, do they have any sewer problems. I would not trust every condo association to be well run.