Yes when you will get sediment build up in city pipes 6 inch and bigger
but in 4 inch and smaller the flow of water will keep it at a minium ,
remember you have all your water coming down the pipe so it washes out
also most clogs happen because of roots not waste once again sorry
wrote:
jim wrote:
The minium is 1/2 inch per foot leaving the house to the tank or street

Jim, just out of curiosity: Have you ever run across a situation where
clogs were occurring due to excessive slope? I ask this because there
are those in sewer maintence that have said that excessive slope has
never been a problem with causing clogs. And the study I cited noted
that sediment is less likely to form with increased slope.

In common household sewage lines, you often have lines going from
horizontal to vertical, which would cause the liquids to drop away
pretty quickly, if anything would, but yet solids collecting in the
region before the vertical drop and causing clogs doesn't seem to be an
issue.