peter wrote:
"Speedy Jim" wrote in message
...

Crawl space means no floor drains, as there would be in
a basement. Right? So, all the fixtures are well above
grade level.

In that case, I would say there is zero likelihood of
backup out of toilets/sinks due to stoppage/flooding of
the city sewer.


Isn't it possible for a neighbor to throw something in the toilet that
eventually clogs the city sewer line? If this happens, then subsequent
flushing or use of water would cause a backup. Or is the city sewer line so
large that nothing passing through a toilet could possible get stuck there?


Yes, indeed, that could happen.
But OP's house (as I understand it) only has
a crawl space with no fixtures below grade.

If the city sewer clogs or backs up, it's unlikely
that could cause sewage to flow from fixtures well
above grade (though one can't rule it out altogether).

Jim




If there was a stoppage, either in the sewer or in your
lateral connection (tree roots) AND you flushed a toilet,
then it would/could backup within your house.