I have to do a costly sewer line fix and repair, this calendar year. Is there any tax break that I can claim on the same?

No, if this is for your personal residence. If this is business property, you may be able to claim this as either a repair expense or a depreciable improvement to your property.

I have a rental house that needed a repair this year. How do you determine if it is a repair expense or needs to be depreciated as an improvement?

It was a sewer line repair.