# How far should a P Trap be from the source drain



## msukazman (Oct 4, 2010)

I have been experiencing a issue with my shower drain in my new house (new but the warranty is over). It is collecting buildup (similar to the texture of a butterfinger candy bar) in the drain. I went into my basement to examine it a bit further and what the plumber did was put a 90degree elbow right after the shower drain flange and ran the pipe about 4 feet horizontally to another elbow that then interfaces with a p trap. It apears to me that the 4ft section of horizontal pipe is what is getting clogged but i can't really tell. 

What would cause water to stay in that pipe... is it not graded enough? Could it be because the P trap in and out are at similar levels?
Is there a possible venting issue causing this standing water in the horizontal pipe or is it likely just because the trap was not placed directly under the shower?


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## TheEplumber (Jul 20, 2010)

IMO, your plumber did a poor job. Your trap should be directly under the drain. Is there some kind of obstruction that wouldn't allow that?
Maximum length for a 2" trap arm is 5ft. Is the shower drain within that length? If so, you can move the trap to the drain location. Also, check the grade on the pipes, you want 1/4" per ft fall.


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## msukazman (Oct 4, 2010)

I would definitely agree with your assessment of the plumber that did the work. There is no obstruction or reason not to put the trap under the drain. another thing he/she did that is obviously shotty is the roughing for the basement toilet... he used 3 inch instead of 4 and put the elbow so high that you can't even put a internal flange on the thing... I ended up having to build up the floor and chisel away concrete just to get enough reveal.... 

no comment on my builder either... she obviously doesn't take pride in her work... they used the cheapest products she could get away with in many areas... oh well.... live and learn..


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## TheEplumber (Jul 20, 2010)

msukazman said:


> I would definitely agree with your assessment of the plumber that did the work. There is no obstruction or reason not to put the trap under the drain. another thing he/she did that is obviously shotty is the roughing for the basement toilet... he used 3 inch instead of 4 and put the elbow so high that you can't even put a internal flange on the thing... I ended up having to build up the floor and chisel away concrete just to get enough reveal....
> 
> no comment on my builder either... she obviously doesn't take pride in her work... they used the cheapest products she could get away with in many areas... oh well.... live and learn..


The WC 90 positioning is too bad. However, 3" is the norm for toilets. Over 20 yrs plumbing and I can count the times on one hand I used 4" for toilets. The engineers speced it on those occasions. 4" toilet lines are not that common these days. Also, my code allows me to put 3 toilets on a 3" drain line.


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## msukazman (Oct 4, 2010)

TheEplumber said:


> The WC 90 positioning is too bad. However, 3" is the norm for toilets. Over 20 yrs plumbing and I can count the times on one hand I used 4" for toilets. The engineers speced it on those occasions. 4" toilet lines are not that common these days. Also, my code allows me to put 3 toilets on a 3" drain line.


I understand the fact that the line would be 3" but the issue is that he didnt install a flange on it so obviously someone was going to have to... since thats the case, it has to be a flange that is 'inside' the exposed pipe. if they weren't going to put a flange on it, then there should have been a 4" interface so i could slide a 3" flange into the 4"


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## braindead (May 31, 2010)

>>>I understand the fact that the line would be 3" but the issue is that he didnt install a flange on it so obviously someone was going to have to... since thats the case, it has to be a flange that is 'inside' the exposed pipe. if they weren't going to put a flange on it, then there should have been a 4" interface so i could slide a 3" flange into the 4"<<<

You usually only install the flange when you know what the finished floor level is, a lot of times you don't know before the floor is poured or finished.

You should never use a inside flange on a 3in. line, it shrinks the i.d. of the line too much. :no:


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## Ltnicks (Nov 9, 2010)

about the shower, did you clean out the trap? we can only wonder why the plumber went the way he did with the drain, I wonder if it was to get it closer to a code compliant vent distance.

are you sure the 3" was roughed for a W.C?


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## msukazman (Oct 4, 2010)

braindead said:


> >>>I understand the fact that the line would be 3" but the issue is that he didnt install a flange on it so obviously someone was going to have to... since thats the case, it has to be a flange that is 'inside' the exposed pipe. if they weren't going to put a flange on it, then there should have been a 4" interface so i could slide a 3" flange into the 4"<<<
> 
> You usually only install the flange when you know what the finished floor level is, a lot of times you don't know before the floor is poured or finished.
> 
> You should never use a inside flange on a 3in. line, it shrinks the i.d. of the line too much. :no:


I completely agree about having to use a inside flange on a 3in. line... thats why i made the comment... I really dont think the guy was thinking.




Ltnicks said:


> about the shower, did you clean out the trap? we can only wonder why the plumber went the way he did with the drain, I wonder if it was to get it closer to a code compliant vent distance.
> 
> are you sure the 3" was roughed for a W.C?


Your really making me wonder if he did plumb it as a W.C.... what would i look for if i had pictures before the basement cement was down... and also... if it wasnt plumbed with the intentions of being a W.C.... what could go wrong?


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## TheEplumber (Jul 20, 2010)

msukazman said:


> Your really making me wonder if he did plumb it as a W.C.... what would i look for if i had pictures before the basement cement was down... and also... if it wasnt plumbed with the intentions of being a W.C.... what could go wrong?


There numerous ways to do it. It is somewhat dictated by site conditions. I rough in a toilet 12.5" from the backwall framing and at least 16" from the side wall framing. You should see a 90 (no trap) just below the slab, some times its real shallow, other times its deeper. Depends on how much depth you have below floor. Within 6ft downstream of this 90 you should see a 2" vertical vent for the toilet. It may be 3" if it serves as a clean out also. This vent may also have the lav wet vented into it. Once the floor is poured you should have a 3" pipe sticking up. Hopefully its sleeved from the concrete enough to allow you to install a flange over it. Hope this helps some. I googled for some pictures but didn't find any I liked.


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## msukazman (Oct 4, 2010)

TheEplumber said:


> There numerous ways to do it. It is somewhat dictated by site conditions. I rough in a toilet 12.5" from the backwall framing and at least 16" from the side wall framing. You should see a 90 (no trap) just below the slab, some times its real shallow, other times its deeper. Depends on how much depth you have below floor. Within 6ft downstream of this 90 you should see a 2" vertical vent for the toilet. It may be 3" if it serves as a clean out also. This vent may also have the lav wet vented into it. Once the floor is poured you should have a 3" pipe sticking up. Hopefully its sleeved from the concrete enough to allow you to install a flange over it. Hope this helps some. I googled for some pictures but didn't find any I liked.


the distance from the wall was fine for a toilet... because i specified its location and that it be for a WC... but I myself wouldnt know if they had to do anything more then use 3in and put it where i asked. 

the issue was with the last part of what you said... he installed no flange and the 3in. pipe coming up out of the concrete was almost nonexistant since the elbow coller was within a 1/4 inch from the floor finished surface... what i ended up doing was trimming the WC flange to about a inch and installed the basement subfloor to raise my level to give the appropriate reveal of the flange. Everything is in working order so i am hoping there is no issues down there... but haven't had it operational for more then a few months now... so i dont know what the future holds... Thats why i was wondering if there would be anything i could see to identify issues before i put down carpet and tile everywhere


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## msukazman (Oct 4, 2010)

Ltnicks said:


> about the shower, did you clean out the trap? we can only wonder why the plumber went the way he did with the drain, I wonder if it was to get it closer to a code compliant vent distance.
> 
> are you sure the 3" was roughed for a W.C?


Thats a interesting comment you bring up about having to be nearer to a vent possibly... because honestly i dont even see a vent for this portion of the system... but maybe i missed it... If cut everything up and put the trap directly under the drain, could I really be any worse off then what i am now?


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## Homerepairguy (Aug 1, 2010)

TheEplumber said:


> The WC 90 positioning is too bad.


What's a WC?


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## msukazman (Oct 4, 2010)

Homerepairguy said:


> What's a WC?


i believe it stands for water closet.... fancy word for toilet


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## Ltnicks (Nov 9, 2010)

if the 3" coming out of the floor is for a W.C. (water closet) then im sure what the plumber was thinking is that you will cut the pipe flush with the floor, mark where you need the threaded rod comeing out then drill an anchor in the floor, then you can put in some threaded rod ( brass) put the wax ring on the toilet and set it into place


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## rudolph58 (Mar 11, 2009)

From fixture to trap in IL. is 2'6"


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## Jim F (Mar 4, 2010)

Homerepairguy said:


> What's a WC?


I think they are actually talking about the flange piece.


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## TheEplumber (Jul 20, 2010)

Jim F said:


> I think they are actually talking about the flange piece.


No, WC stands for water closet. aka toilet


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