Sewage has a problem but that is city's responsibility

[Oleg Serdyuk]

I am about to purchase a single family house. 

Sewage inspection indicated that there are some cracks, pipe separation where two pipes connect, etc, but nothing very serious. 

The bigger problem was mentioned in a report is a little "belly" in a hub or "void" , and eventually it will collapse pipe.  But that is on a city side. 

So do I need to worry about it?

Let's say it collapsed, I called a city, how quickly they going to fix it? 

Will I have to pay anything for that or everything is gonna be paid of by the city?

Thank you