Mystery drain hose into bathroom sink drain

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Electron2002

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I've been in my condo for better than 3 years and for some reason had never really inspected the plumbing under the bathroom sink. When I started doing a little bathroom remodeling, I noticed that there is a 7/8" drain hose coming out of the wall and into the down pipe above the P-trap.

The wall that the hose is coming out of is shared with the side wall of the second bathroom's shower, so there shouldn't be anything over there to drain away.

When I pulled the hose off, I found that there was hair and other crud at both ends of the hose. To me, it appeared that there was some actual drainage that was coming through the hose.

Since the work I was doing was going to take a few days, I went ahead and reconnected the hose, since I had no idea when there might be something coming out of that hose. When I checked the trap again later on, I found water had collected in the trap. So there is something actively draining into my sink drain.

The only additional plumbing fixtures that are in the general area of the drain are 2 sinks and the previously mentioned shower. Tests haven't identified any of these as possible sources.

My ultimate question is... Is it possible that this is drainage from one of my neighbors units? Would it have even been to code for a plumber to have even set things up like this?

I haven't had any actual problems occur as a result of this, but I do find it somewhat concerning. Below is a photo of the plumbing in question.

Thanks

photo3_zpsf920d23a.jpg
 
johnjh2o said:
It looks like it's an air conditioner drain.
Click to expand...

I had considered that as well, but I haven't been running my a/c for several weeks, for there to be any water coming out of it and I wouldn't think there would be hair found in a condensation drain line.
 
johnjh2o said:
The hair is from the sink drain. That is the AC drain.
Click to expand...

If that is correct, I am okay with that.

But can you explain how hair from the sink would manage to migrate uphill in an 18" hose or how an air conditioner would produce condensation and fill a P-trap when it hasn't been run in literally months?
 
I don't understand your point about filling the trap. The trap is also being used for the sink drain that keeps the trap filled. As far a hair getting into the hose that can happen when you drain a sink full of water.
 
My apologies for not being clearer. The sink hasn't been in use, because I've been remodeling the bathroom and for much of the time that I was noting water from the hose, there was no sink at all.

The photo I provided was taken after everything was put back together.
 
Based on our upc codes in the Northwest, you can not directly tie a condensation drain or overflow drain or any type of relief drain such as hwt or drain pan, to a waste pipe with out the use of an air break.
If you don't understand what an air break is, a simple example is the dishwasher air gap. It is designed to prevent the main drainage fixture, your disposal, from overflowing into the additional connection, your dishwasher. Right now it appears that if your sinks drain was to plug and overflow, you have the potential for grey water to back up into the AC, furnace, maybe even the hot water tank, could be a drain pan as well. Any scenario it is bad and should be changed.
 
Interesting point regarding the air break. I'm not sure if there is a difference in the code here in Southern California, but I am familiar with air breaks and can appreciate why one would be necessary on a condensation drain. In the case of my property, the A/C evaporator is in the attic, and there may be an air break up there, I haven't been up there recently to recall how it is set up. I think I'm going to have to make a trip to the attic to check for an air gap and to verify if the condensation drain line leads to where that bathroom wall is.

To John's comment that it is possible more than one A/C could be hooked up to a single drain line, would something like that meet code?
 
Even if there is an air break at the unit in the attic, it will not protect you from having sewage back up into the condensation line. The air break needs to be between the condensation line and the waste line to operate safely.
 
AQualityPlumber said:
Even if there is an air break at the unit in the attic, it will not protect you from having sewage back up into the condensation line. The air break needs to be between the condensation line and the waste line to operate safely.
Click to expand...

It's called an air gap. And it can be in the attic to protect the line. Besides that if the AC is above the flood rim of the sink I see no way that sewerage could reach the AC unit.
 
I'm not disputing if it's possible for sewage to reach the AC unit in the attic, but it is possible for the line to plug up if the sink becomes plugged, resulting in possible over flow of contaminated water into the AC unit. Bottom line at least in Washington state is you can not connect any kind of relief line to a sewer pipe without the use of some kind of approved air break or air gap. The proper method would be to run it outside or run it into its own independently trapped drain with a trap primer. That's our code, these will change based on the authority having jurisdiction.
 
I agree with aquality, up here its the same deal, minimum air break of 1". Air gap in my code is defined as something like a kitchen sink tap to the flood level rim of the sink. Gap for me is with water supply, break is for drainage of equipment like ac, or water softener or food equipment etc. But every area is different so it could be different depending on where you live.
 
I just have a minute, but still want to chime in.
The distance from the tap/spigot of the sink to the flood level rim of the sink is an air gap that is usually referred to by "critical level" (usually a minimum of 6" by codes) to avoid siphonage and cross contamination.
An air break is when a smaller sized pipe penetrates below the flood level of a fixture or drain.
The air gap is when the pipe maintains a distance between where it terminates and where the flood level of the fixture or floor drain begins, (as john said).
Just sharing information to clear up controversy. Don't wanna step on any toes.
Back to work, breaktime is over.
 
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Fair enough, in my schooling they taught it differently but in Canada they may have a different meaning or the code may have a slight variation from yours but that's good to know. In my code it's minimum 1" or 2 pipe diameters whichever is greater. 6" is the CL for an atmospheric vacuum breaker in my code (exception being fill valve on wc) but again it may be different depending on the area
 
Just to clear up what I said in my post was there could be an indirect waste up in the attic. I didn't say one wasn't required as it is required. But the other point I was making was there is no way contaminated water could reach the AC pan as it would overflow the sink first.
 
johnjh2o said:
Just to clear up what I said in my post was there could be an indirect waste up in the attic. I didn't say one wasn't required as it is required. But the other point I was making was there is no way contaminated water could reach the AC pan as it would overflow the sink first.
Click to expand...

Not necessarily. True if the sink plugged it would likely overflow into the sink. But imagine hypothetically the sink does clog up with hair grease and gunk, the condensation drain is tied to the plumbing upstream of the trap below the flood level. Now sink plugs and overflows I into the sink bowl. The section of condensation line below the flood rim is flooded with the waste water. Now this can create the plug because again true the line would not overflow from sink but if the sink plugs, so does the condensation line which will keep dripping as long as A C unit is running. Am I painting a clear enough picture of how the condensation line can flood back into the unit in the attic. Not to mention I've had to at times pour acid down drains to unplug them from greases. Would you want to dump sulfuric acid down a drain with your ac condensation line connected directly to it. This is just simply a perfect example of unsafe plumbing connections. Enough said.
 
Even if you had the condensate line run to the outside and it plugged it would flood the AC pan. The pan can flood but it would be from the condensate not the contaminated sink drain. My point is there is no way contaminated water can reach the AC pan in the attic. Again I'm not saying an indirect waste isn't required as we all know that it is.
 
I would like to chime in as well. I agree with John that the line is from the air handler drain pan -- I have also seen where the drain pan line is sticking out of the ceiling above the lav sink ( in condos and commercial business). Although tapping a drain pan line into a drain like shown is not code these days, that did fly back then but will need upgraded when a replacement system is needed (the setup shown will not be grandfather in). I also think the condensate drain line from the evaporate is plumb to another source. In condos and commercial business the drain pan line was ran to the lav sink in case the condensate drain clogged (or the system frozed and thawed) someone would hear water running.
 
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