Minimum sewage pipe slope
Minimum sewage pipe slope
(OP)
What is the minimum slope one can use on a sewage system with less than 25 fixture units?
I know that 1% is acceptable and sometimes 2% is the least recommended...
can you use on that system a pipe with 0.5% slope?
And let say i used the manning formula to see if a given slope is acceptable..how should i analyze the answer? should the velocity be below 6fps ?
I know that 1% is acceptable and sometimes 2% is the least recommended...
can you use on that system a pipe with 0.5% slope?
And let say i used the manning formula to see if a given slope is acceptable..how should i analyze the answer? should the velocity be below 6fps ?





RE: Minimum sewage pipe slope
Inside slopes are determined by the applicable plumbing code.
In the IPC world, 25 fixture units would be 3 or 4", depending on what type of drain (building drain or branch). At that pipe size, minimum pipe slope is 1/8" per 1 foot, which is ~1.04%
Outside slopes are typically determined by expected flow rates and maintaining at least 2 fps velocity. Personally, with 25 fixture units, I would not go less than 1%, but sometimes the minimum outside pipe size is 6" so you might need to be at 2% to maintain velocity.
RE: Minimum sewage pipe slope
RE: Minimum sewage pipe slope
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Minimum sewage pipe slope
RE: Minimum sewage pipe slope