# Drain for a Pedestal sink



## Bob Mariani (Dec 1, 2008)

as long as you do not mind the gurgling that you will experience.


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## Shoogy (Jan 14, 2009)

zachsdad said:


> *Is there any reason why I can't or shouldn't run the drain for a pedestal sink straight down through the floor, leaving nothing showing as far as the drain is concerned, as long as it dumps into 1 1/2" schedule 40 PVC with a trap under the floor? The bathroom was a total gut so I have plenty of room to run all new DWV to the existing stack. Thank you in advance for your feedback.*


well it dosent sound rite id say there are several reasons to NOT run yur drain straight thru the floor corect installation of a ptrap is about 12 inches below the sink and it should eject horizantaly into a vent that is usualy inside the wall. the vent is my concern sounds like you dont have one an improperly installed ptrap can allow sewer gases to get inside yur home its a saftey issue.can cause ododr issues as well as health problems


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## zachsdad (Jan 14, 2009)

*This forum is a good way to learn things and this very well might be a concern but correct me if I'm wrong. Doesn't the overflow on all sink and bathtub drains provide air into the system to equilize the pressure that is created when water flows away from a fixture and eliminating this problem ?*


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## Bob Mariani (Dec 1, 2008)

no, it provides an overflow so the water does not spill onto the floor.


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## bradnailer (Nov 13, 2008)

If you will have easy access to the trap, what you are proposing will probably work but it isn't the best plumbing arrangement. Oftentimes, to clear a clogged drain, I've had to remove the trap and it would suck if I had to crawl under the house every time to remove the trap.

I guess I'm not offended by the drain pipes running into the wall behind a pedistal sink. You can use chrome, brass and even oil rubbed bronze drain lines which will look OK. In fact, I have a pedistal sink in a small bathroom and our fixtures are oil rubbed bronze. I used normal PVC drain pipe and painted it with rattle can oil rubbed bronze paint and it looks just fine.


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## Bob Mariani (Dec 1, 2008)

I did a job a while ago and the vent was in the wall, but I placed the trap in the basement to allow more storage space in the kitchen sink cabinet, It does work, but when it drains, it gurgles and I had to more the trap back into the cabinet to fix it. Not sure why, but this was my experience.


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## wrangler (Oct 9, 2008)

"Why" is because you have 3 feet of air that needs to escape to allow the water to drain, thus the gurgling. I would also be worried that if something fell into the drain, such as a ring, you'd have a hard time getting to the p-trap to remove it.


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## zosoplumber (Nov 21, 2008)

A vent needs to be before a p-trap, what you are saying that as the water flows through the p-trap, its pulling the air from your bathroom down with it, but the water keeps pulling the air through and syphons the water from the p-trap, leaving a dry p-trap to stink your house up. You must vent before the p-trap and your vent should run vertically or no less than a 45 degree angle until above flood rim (around 42" AFF in bathroom). If venting is an issue for you, you might be able to get a air admtance valve(studder vent) behind the pedestal.


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## zachsdad (Jan 14, 2009)

*I would like to thank everyone who replied to my thread/question. I took your advice and went ahead and put the trap where it should be, on the tail piece, and ran it back into the wall and over to an existing cast 4" DWV. I had to cut a section out of the cast and put a "Y" fitting in with the rubber couplings. I did not want to cut the cast twice to do the vent so I took zosoplumber's advice and used a air admittance valve (studder vent)? straight up 2 1/2' from the sanitary tee behind the sink. Hooked up the water supply, filled the sink, pulled the plug and it worked great. No gurgling, no nothing. The This Old House website calls installing a pedestal sink "the graduate school of the do it your selfer" and after doing this I have to agree. No dreaded "tink" from tighting the lag bolts, no leaks, and very solid. Looks great. I'm glad I asked the question here and again thanks for the good advice. zachsdad*


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## designengineer (Oct 17, 2016)

Much, much too late for Zachsdad, but maybe of use to some one who picks up the thread later.

The simple and correct answer to Zachsdads' question is: Yes you can just put a vertial waste pipe straight down, hidden within the pedestal, but you MUST fit, directly to the basin, a Staight Pedestal Trap. These are specially made to allow for hiding the pipwork within a pedistal. Also run copper hot and cold feeds up from the floor (with in line isolater taps for later tap seal maintainance ect), and you then have all you pipework descreatly hidden: This being the whole point of pedestal sinks. 

I reccomend the FloPlas Sraight Pedestal Trap (available from Screw Fix and other suppliers for about £6), very easy to fit with built in height adjustment of 90mm.


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## Ghostmaker (Mar 2, 2013)

Interesting but bottle traps are not use able under IPC code.


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