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House on a hill, 400'+ from the street lateral. GC wants to horizontal drill sewer line. His question to me: If minimum slope is 2%, what is the maximum slope? Because of the slope of the hill, some of the grades between clean outs (100') could be as great or greater than 20%. My 2007 CPC does not address the issue. My experience is that it doesn't matter. But, I told him I'd ask for 2nd opinions.
 

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Too much pitch combined with 1.6 GPF toilets = lots of soft blockages of the sewer.

That is not from any code, just a personal observation. If you do install this with radical pitch I would recommend putting in a CO at the tie in to the main that you can jet in both directions from.
 

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Too much pitch combined with 1.6 GPF toilets plus an over sized sewer = lots of soft blockages of the sewer.


There, fixed. In my opinion anyways.
 

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Too much pitch combined with 1.6 GPF toilets plus an over sized sewer = lots of soft blockages of the sewer.


There, fixed. In my opinion anyways.
:thumbsup: Lotta codes still figure DFU's based on the old big flushers.

I read in PE one time that too much slope is a myth. I'm no drain cleaner though. Proofs in the puddin:laughing: pun intended
 

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There is no maximum pitch here. Only minimum. I have installed sewers and drains with a very strong pitch and they never had any problems. Of course, back-pitch or not enough pitch causes huge stoppage problems.
All so true, we live in a place that houses are up in the hills, and I can tell you it's a myth that too much slope leaves sewage behind. Min pitch 1/4" per ft but it can have 1/8" per ft is grade is not happening at 1/4"
 

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I don't believe any codes have a maximum allowable pitch for drainage piping, otherwise places like San Francisco would be in real trouble. Besides a vertical stack is about as "maximum" as you can get.
 

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Up here the code says Min. 1/4" per foot for 4" and under and 1/8" per foot over 4". It also states that " Steeper slopes and higher velocities will help keep the pipes clean by moving heavier solids that might tend to clog the pipes. I aim for 1/4" per foot as a guideline.
You sure you didn't mean 1/8" @ 4"?
 
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