[Plumbus]

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.

 

[user4]

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.

 

[22rifle]

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.

 

[ILPlumber]

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

 

[user4]

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.

Our code calls for a minimum 6" once it leaves the building.

 

[Plumbus]

Our code calls for a minimum 6" once it leaves the building.

Fortunately, ours doesn't. The two way CO is a good idea, thanks.

 

[service guy]

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.

 

[22rifle]

Our code calls for a minimum 6" once it leaves the building.

I knew that. 6" CI and one or two 1.6 toilets? I would be running it right on grade myself.

4" PVC and the same toilets? Completely different story in my opinion.

 

[Plumberman]

1/4 per foot on 4". Standard Plumbing Code.

 

[user4]

I knew that. 6" CI and one or two 1.6 toilets? I would be running it right on grade myself.

4" PVC and the same toilets? Completely different story in my opinion.

Our code doesn't allow PVC sewers either, it is all clay or cast iron.

 

[Plumberman]

Our code doesn't allow PVC sewers either, it is all clay or cast iron.

Just curious... What are the city mains run in?

 

[user4]

Just curious... What are the city mains run in?

24" and under are run in clay, over twenty four inch are either brick or concrete, depending on whether they have been replaced or not. Anything over 60" is relatively new, and is concrete.

 

[Ron]

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"

 

[Plumberman]

24" and under are run in clay, over twenty four inch are either brick or concrete, depending on whether they have been replaced or not. Anything over 60" is relatively new, and is concrete.

Got ya.... Thats some big a clay!

 

[user4]

Got ya.... Thats some big a clay!

Chicago is a big city, and 70% of the sewers go to the same treatment plant for the entire county.

 

[uaplumber]

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.

 

[nhmaster3015]

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.

 

[GrumpyPlumber]

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"?

 

[Alan]

You sure you didn't mean 1/8" @ 4"?

It looks like those slopes were based on pipe size.

 

[uaplumber]

You sure you didn't mean 1/8" @ 4"?

Oops, my bad! . Must have been too close to the primer again.