I have a 3" Septic line that is under neath the floor joists and needs to
get to a 5" chase in the Foundation. Its about a 2' elevation difference
from the 1/4" foot run elevation and the chase.
Then from the Chase to the Septic Tank I need to again do a rapid decent
from the chase to the level that will give me 1/4" foot out to the Septic
So my question is this, do I do a Right 90 down in elevation, and 90 over or
do I do a 45 and 45?
Seems like the 45/45 is the way to go, but I don't want my liquids to run
away from my solids. In keeping with the theory of a multi story house. its
all 90/90 to get from floor to floor.
So what should I do??
There is such a thing as minimum slopes for sewage lines, but not a
maximum slope. The more slope, the better. The liquids running away
from solids and causing clogs theory is a myth. High flow velocity is
good. See this:
Vertical lines are used all over the place, between floors and down to the
basement floor for sewer and drain lines. If you have the space you could
use two 60 degree ells as they take less room than two 45 degree ells. If
you don't have or want to use the space you can use two 90 degree ells,
however you may want the bottom one replaced by a wye topped with a 45 to
achieve 90 degrees with a clean out in the other inside end.
Spoken like a plumber who knows s--- flows down hill then your brain
should be on the floor the site you talk about is dicussing street
sewers oboy 45 45 is the way to go 30 yrs plumbing I think I know, if
you think that angle is a joke then do it Yellowbird does,nt know what
he is talking about trust me.
The minium is 1/2 inch per foot leaving the house to the tank or street
you should never have more than 1 inch per foot or the solids will be
left behind in the pipe. If you are putting elbows in the stack they
have to be 45s with no more than 2 in the length of the stack,never put
any from the bottom of the stack to the street or tank. My apologies
Yellowbird for being very rude a dram to many no excuse sorry
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
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
. firstname.lastname@example.org wrote:
In hopes of putting this myth to rest once and for all, I found another
article specifically on the subject from Plumbing & Mechanical
Magazine. Here's an excerpt from a Google cache of the article:
One of my favorite stories about George occurred at a Plumbing
Exposition. George was on the Board of Directors of the ASPE Research
Foundation. He helped set up a demonstration model for the show. The
model had four of these new fandagled 1.6-gpf water closets. There was
a 3-inch drain line in clear plastic pipe. (Installed by a UA
contractor, of course.) The model had different segments of pipe to
demonstrate different flow parameters. One section of pipe was pitched
about 3 inches per foot.
As the show was about to begin, George was speaking to a few of us
standing around. He looked at this steeply pitched pipe and said, "We
might have a problem with stoppages in this section of pipe. I'm afraid
the liquid will be running away from the solids." I just smiled.
As the demonstration began, they flushed carrots, beets and peas. When
the vegetables hit the steep section of pipe, they took off down the
pipe, flying at a high speed. George looked over at me and said, "Well,
I'll be. You knew that was going to happen, didn't you? You see, my
apprenticeship instructor always taught us that if you pitched the pipe
too much, the liquids would run away from the solids." I said to
George, "My plumbing instructor said the same thing, but my engineering
professor explained why this is a plumbing myth and would never
happen." For the next hour we spoke about engineering principles. Here
George was in his 70s learning new concepts so he could relay the
information to others.
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