How do PVC sewer lines get sloped using 90 degree fittings?

[Stephen Tashi]

TL;DR Summary

A geometrically pefect horizontal pipe attached to a vertical pipe witha 90 deg fitting wouldn't have any slope. So how, in practice, do horizontal sewer lines get sloped?

Diagrams of PVC sewer plumbing show vertical pipes connected to horizontal pipes with fittings that make a 90 degree turn. So how, in practice, do we achieve the recommended minimum 1/4 inch per foot slope for the horizontal pipes?

Do we make the horizontal pipe slope by installing the vertical pipes not perfectly vertical?

Or do we install the pipes in the 90 degree fitting slightly askew?

Or do we glue the pipes in the fitting without worrying about the slope and then bend the pipes slightly so he horizontal pipe has slope?

Or perhaps a nominal 90 degree fitting actually turns more than 90 degrees?

 

[anorlunda]

ping @AK_NC

 

[Averagesupernova]

The beauty of PVC drain pipe is there is enough give to get that kind of slope when transitioning from vertical to horizontal. I have been told two different stories on how much a pipe should be sloped. 1/4 inch drop per foot of run is recommended for 2 inch pipe and smaller. I have had a plumbing inspector tell me 1/4 inch drop per foot on anything larger than 2 inch pipe also, and another reliable source says only 1/8 inch drop per foot on anything larger than 2 inch pipe.