In a recent renovation, a bathroom was added and the waste pipe runs about 20-30 feet across the house to tie into the main sewer line. Water seems to flow out to the sewers, but waste is getting stuck in the waste line and eventually backs up. The clogs seems to be in or around the 45 degree elbow at the end of the line, where the waste pipe ties into the main stack. The plumber swears the pitch is fine, but is now questioning whether it is due to the fact the toilets are now low gallons per flush, and I might need a power flush toilet. Any suggestions? Thanks

waste is getting stuck in the waste line and eventually backs up. The clogs seems to be in or around the 45 degree elbow at the end of the line, where the waste pipe ties into the main stack Is that the only bend in the drain line?
Why wasn't there a straight shot at the stack? Could the 45 be removed and the line straightened out?
It's not the toilets I question but the "cock angle" of the 45. I*f that's the offending fitting then let's quit blaming the toilets and focus on why the line won't accept solids. Good luck, Tom

This happens when you do not connect new and old correctly. Do you have a picture of theth connection ? If positive - post it.

Also, we always snake new to old sewer bcs there is always some construction debris that falls into the pipe during construction.