I know sewers back up. The question is what, if anything, I should do to prevent it from happening in my home.
Or to put it another way, since sewers do back up, should every residence everywhere should have a backflow preventer?
No. Some should have overhead sewers.
So next you say, ok, should should every residence everywhere without overhead sewers have a backflow preventer?
I would say no. Single story houses with a crawl space that are not in low areas would probably not need one... And next you say, ok, should should every residence everywhere ....
I don't need a backflow preventer with my septic and overhead sewers.
If I were on a sewer, if I don't have a lower basement that the people downstream of me, and those people have not flooded, I would think a backup is not going to help. When those people flood, and put in measures, the problem moves up hill.
I would say that if you are going to put in an anti-backup valve, get one that works. Most in my non-pro opinion won't work because they are those flappers that leak.
And again, I would talk to the sewer people. I think they are likely to be forthcoming.