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TheMole
join:2001-12-06
USA

TheMole

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[Plumbing] Maximum Pitch on Waste Line

We had a bar sink installed in our pantry and the plumber ran a new waste line. The work passed rough inspection. We are not to final inspection yet, as the larger project is not complete. The waste line runs in our unfinished basement and is exposed for visual inspection.

In the meantime, we are having other work done and there is a different plumber at our house today (not connected to the company from the pantry bar sink). As soon as the different plumber came into the basement, he noticed the new drain line and said that the pitch is TOO much and that the plumbing inspector should have failed it.

He said that with the pitch being too much, solids will sink to the bottom of the pipe and the water will move right past them. He said the code requires 1/4 per foot so that the water moves slower and moves solid waste with it.

He said that we should have it fixed.

A quick google search yields mixed results. Some hits report that there can never be "too much pitch" others agree with the second plumber.

what say you all? should i insist the original plumber fix it, even though it passed the rough inspection?

Camelot One
MVM
join:2001-11-21
Bloomington, IN

Camelot One

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There is a minimum drop that has to be maintained, but I have never heard of too much. But if one of the plumbers is quoting it as code, a quick call to your local authority should get you the definitive answer.

garys_2k
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join:2004-05-07
Farmington, MI

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I've never heard of too much pitch, either. Too large a pipe can allow solids to not be sufficiently pushed along by the liquids, but you'd have to have a stupidly too big pipe for that to be an issue. Fact is, solids will "fall" better with a steeper pipe slope as well as liquids.

davidg
Good Bye My Friend
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if that were true then how are vertical drops allowed to go from upper stories to the basement/ground floor?

nunya
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O Fallon, MO

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Shit rolls downhill.

mattmag

join:2000-04-09
NW Illinois

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According to the International Plumbing Code, 2012 edition, Section 704, Drainage Piping Installation;

"Horizontal drainage piping shall be installed in uniform alignment at uniform slopes. The slope of a horizontal drainage pipe shall be not less than that indicated in table 704.1"

Table info:

Pipe Size ---------- MINIMUM Slope (inch per foot)

2 1/2 or less -------- 1/4

3 to 6 -------------- 1/8

8 or larger ---------- 1/16

There is no mention of Maximum.

LazMan
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join:2003-03-26
Beverly Hills, CA

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I've heard of the "too much pitch" thing before, as well - but have no idea if it's a valid argument or not... I try to do as little plumbing as possible, to be honest.

If the inspector is happy with it; I'd chalk it up to one plumber cutting up another plumber's work, and call it good.

robbin
Mod
join:2000-09-21
Leander, TX

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said by davidg:

if that were true then how are vertical drops allowed to go from upper stories to the basement/ground floor?

I believe that vertical is described as anything over 45 degrees which has different requirements. I don't think code defines a maximum although some seem to think one is implied. That said, slopes between 2% and 45 degrees seem to be a problem area. Probably not a problem for a bar sink depending on the slope but if it is going to be hidden in the wall and it's easy to change it may be worth it to eliminate any future problems.

TheMole
join:2001-12-06
USA

TheMole

Member

said by robbin:

I believe that vertical is described as anything over 45 degrees which has different requirements. I don't think code defines a maximum although some seem to think one is implied. That said, slopes between 2% and 45 degrees seem to be a problem area. Probably not a problem for a bar sink depending on the slope but if it is going to be hidden in the wall and it's easy to change it may be worth it to eliminate any future problems.

»www.nachi.org/forum/f22/ ··· e-15817/

this link seems to agree with you.

Thane_Bitter
Inquire within
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join:2005-01-20

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said by TheMole:

should i insist the original plumber fix it, even though it passed the rough inspection?

Yes, he is suppose to be a professional (as is the inspector), explain the issue and the plumber should resolve the fault. Plumbing is useless if it doesn't meet code requirements, doesn't matter who installed it.

TheMole
join:2001-12-06
USA

TheMole

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Graphic from Quote
Thanks all. I"m going to make them fix the slope.

Here is an interesting graphic i found on this and associated write up:
said by »inspectapedia.com/plumbi ··· oise.htm :

If the drain pipe (trap arm) is longer than 5 feet distance from the vertical plumbing vent stack, or the plumbing drain pipe slope is more than ¼ inch per foot, a 1 ¼ inch diameter pipe will flood.

That’s the same as having no vent. The illustration below shows that air from the stack can’t get into the trap arm, and a siphon results.

As Carson Dunlop Associates sketch (left) shows, the slope for drain piping should be between 1/8 and 1/4 inch per foot for 3 inch or larger diameter pipe, but it should be a minimum of 1/4 inch for smaller pipe such as the sink basin drain in our example above.

The sketch shows what happens if a drain pipe is sloped too little (it doesn't drain and drain pipe clogs develop) or too much (water drains too fast and leaves solids behind, and pipe logs develop).


PoloDude
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join:2006-03-29
Aiken, SC

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I'm wondering how much the OP has to worry about "solids" on a bar sink.

tp0d
yabbazooie
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join:2001-02-13
Bulger, PA

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Dont know where it may or may not be in the code, but I was taught to never exceed approx 1/4" per foot fall, or less than 1/8" per foot fall(only on large pipe). Reasoning was the same about the solids, more so for any sink that could ever handle a solid (food prep sink/etc)

just my 2c

-j

TheMole
join:2001-12-06
USA

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Interesting point. The vast majority of the solids will be coffee grinds. We will be cleaning out the coffee maker in this sink and have always washed the grinds down the drain. I've been told in the past that we shouldn't do that, but in 20 years of washing out the grinds in the sink, I've never had a problem.

However, I don't know what else we might put down this drain and I wouldn't want to force this sink to be limited to liquids only and have to worry about it for years to come.

mattmag

join:2000-04-09
NW Illinois

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How much of a pitch does it actually have?

mityfowl
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join:2000-11-06
Dallas, TX

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I've always lived by the rule of no coffee grounds down the sink except the last little drab stuck in the gold filters.

I don't know where I picked that up.

tp0d
yabbazooie
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Bulger, PA

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Cant confirm this, but I've heard due to coffee's acidity, grounds are good for the drain, as they help break down oils/etc in the line.. hmm..

I make 1 cup each morning with a senseo machine (1cup) and I put approx 2-2.5 teaspoons of grounds down my kitchen drain each morning.. no issues in 9 yrs in this place

-j