backed up nightmare

My waste keeps backing up into the shower. I have snaked and had the city flush the main. The wste will not follow the snake to the main sewer, it just sits at the cleanout and then backup in the shower.

 

msmona: It sounds to me like you have a problem with your air vent. There is a vent pipe from your toilet up through the roof of your house. This lets the air out ahead of the flush, and lets the flush go through.
Have someone go on your roof, and inspect the vent. It may have a birds nest in it or debris or ????? If this does not work, call
a plumber, and probably have the toilet trap removed. It may have something in it that the snake will bypass. For instance, a jar lid, a bar of soap, a small wash cloth. Good
Luck, Jack the Contractor

 

dont worry about removing the toilet
trap because you cant,Its part of the toilet.
how old is your sewer line? is it just the
bath tub that backs up?or does it back up when you flush the toilet,and is this a ground level bath or a 2nd story bath.
if its ground level and the tub backs up
when you flush a toilet then there is most likley a problem in the main sewer in the front yard,It could be a collapsed sewer,
or there could be a belly in the line from
settling, or improper installation.I see
you spoke of a clean out,is that in the front yard,your sewer could be full of roots
creating this stoppage.if you have a cleanout
in the front yard and it stands full of
water something is wrong that is getting overlooked.if you can provide more info
I can assist you further.Robert