# Question about the slope of a 3" line...

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Southpaw134, Feb 3, 2009.

1. ### Southpaw134New Member

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is there such a thing as over sloping (too extreme of an angle) an outdoor 3" sewerline?

I assume there isn't, I assume there are some sewer lines that run vertical..., but assuming is, an, umm...big assumption.

Also, if I have a vertical line that I need to connect to a horizontal line is there a minimum or mximum angle of connection between the two (i.e., 45 or 90 degrees)?

2. ### RedwoodMaster Plumber

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1/4" per foot is a minimum pitch.

The old liquids outrunning the solids is a myth that has been busted.

4. ### krowPlumber

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As far as I know, there is nothing such as oversloping, unless your talking about a p-trap in proximity to a vent.
The minimum slope between 2 connections is 1/4" per ft or 2% there is no maximum

5. ### kingsotallPlunger/TurdPuncher

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ReallyÂ¿ So we just do it because it's codeÂ¿

6. ### RedwoodMaster Plumber

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If you read your code chances are it states that it is a minimum pitch...

7. ### Southpaw134New Member

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Thanks for the replies.

8. ### kingsotallPlunger/TurdPuncher

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I always saw the validity in the liquids outrunning the solids.

9. ### RedwoodMaster Plumber

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Liquids will always outrun the solids. If you flush a toilet with a wad of toilet paper in it do you think that it gets to the city sewer on on flush?

Not a chance!

Infact a sewer relies heavily on other flows to clear the line.

10. ### tjbaudioSound and Light Suppervisor for a School District

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That is one reason the shower is near the end of the line in my house, right after the toilet.

11. ### nhmasterMaster Plumber

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If there were maximum pitch rules then you couldn't run a vertical stack

Sewage systems are designed to move waste at 2 feet per second.

12. ### C NUMBPlumbing Contractor

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In your location it is what Redwood said 1/4" per ft. On the vertical to horizontal use either 2 45's or a long sweep 90.

13. ### quinocampaMechanical engineer in marketing. Uhuh.

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I've inspected all of my drain pipes in the crawlspace. My home is only 20 years old, and the entire drainage system is basically flat. The new lines I'm installing are sloped properly, but I wonder why it was done this way. During my bathroom remodel, I've also found a hard vent duct that was crushed to go over the top of a shower drain in a 2nd floor joist bay, soft HVAC ducts in the crawlspace draped over joists 'til they're choked off, and two bathroom fans with no exhaust ducting attached. One of them was blowing directly into insulation, which was right on top of the fan. I've corrected all of these shortcuts. I will defend my right as a homeowner to do my own work when this quality of work is the alternative. Don't even get me started about last year's contracted attic remodeling.

Last edited: Feb 4, 2009
14. ### Southpaw134New Member

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Thanks again for all of the help and information.

15. ### kingsotallPlunger/TurdPuncher

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Flagstaff, AZ Sitting on an upside down 5 gallon b
Guess this greenhorn has a lot to learn! Thanks for the insight fellas.

16. ### hjModerator & Master PlumberStaff Member

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offset

There is no "code" requirement as to how you make a change in elevation, but the prudent way is to make the transition as smooth as possible. If you have room the best way is to just deflect the pipe, the next best is two 22 1/2 bends, or move on to using two 45's, and if there is not enough space for that, then two 90's is the last option.

17. ### RedwoodMaster Plumber

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18. ### Southpaw134New Member

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Thanks Redwood, that was a good read.

19. ### nhmasterMaster Plumber

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So you'd want the catchers mitt before the bucket.

In a vertical stack the water actually clings to the inside of the pipe and swirls it's way to the bottom. The center is mostly empty.

20. ### hjModerator & Master PlumberStaff Member

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drains

In a vertical stack the water actually clings to the inside of the pipe and swirls it's way to the bottom. The center is mostly empty.

Which is why they make "anti vortex" roof drains so the pipe WILL be full and thus can be made smaller.

21. ### rmelo99Network Engineer

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