How can I find the cleanout for my building drain?

[sevensages]

TL;DR Summary

How can I find the cleanout for my building drain?

I am a long distance truck driver, but I recently completed a plumbing program with Stratford Career Institute. In the chapter of my textbook Repairing DWV Systems, the author says that if there is a clog in the building drain, one can clear out the clog by using a snake augur or maybe some other type of tool into the cleanout for the building drain. The author said that the cleanout for the building drain is usually near the stack.

I live in a duplex townhouse. Just out of curiosity, I would like to locate the cleanout for my building drain. Today I am on hometime from my trucking job, and I went to my house and looked for my building drain. I don't think that I found the cleanout for the building drain. There is a 3" or 4" diamater plastic pipe coming out of my house at the back of my house. This 3" or 4" diameter plastic pipe coming out of my roof might be the stack. But there is no cleanout for a building drain directly below this plastic pipe that might be my stack.

My townhouse is built on a slab foundation. So there is no basement or crawl space.

There is a 1/2" or 3/4" diameter plastic drainage pipe coming out of my wall in my backyard, but it is not directly below the stack. Below are two photographs of this 1/2" or 3/4" diameter plastic drainage pipe coming out of the wall in my backyard. One photograph is a close up photograph, and the other photograph is more zoomed out.

For some unknown reason, PhysicsForums rotated my photographs 90 degrees to the clockwise.

Do you think that the 1/2" or 3/4" diamater plastic pipe in the photographs above is the cleanout for my building drain? If not, how can I find the cleanout for my building drain? Is it possible that there is no cleanout for my building drain? If there is no cleanout for my building drain, how would a plumber clear out a clog in my building drain?

 

[sevensages]

It just occurred to me that some people might think that the plastic pipe in the photographs in the OP are my A/C condensate line.

I know where my A/C condensate line is at my house. The plastic pipe in the photographs in the OP is not my A/C condensate line.

 

[Lnewqban]

That PVC pipe sems to be located next to a condenser unit or heat pump.
That location is typical of a condensate or overflow pipe coming from an air handler unit.

The clean out port you are looking for should look like a plug in a 3 or 4-inch tee.
It is normally located at grade level around one foot from the exterior wall.

It could also be found in an exterior wall (vertical drain pipe in the wall) or flush with a driveway surface (brass cover).

Please, see:
https://redcapnow.com/help-guides/where-is-the-sewer-cleanout-in-my-florida-home

 

[sevensages]

That PVC pipe sems to be located next to a condenser unit or heat pump.
That location is typical of a condensate or overflow pipe coming from an air handler unit.

My HVAC unit is a split-system heat pump. The plastic pipe in the photographs in the OP is NOT located next to the outdoor unit of my heat pump.

The condensate line for my heat pump is located right next to the outdoor unit of my heat pump.

The plastic pipe in the photographs in the OP might not be the cleanout for my building drain, but it is part of the plumbing system somehow.

About three years ago a water surge simultaneously destroyed my pressure regulating valve, my T/P relief valve, and the expansion tank on my water heater. After my pressure regulating valve, my T/P relief valve, and the expansion tank on my water heater became defective, a steady stream of water started leaking out of the plastic pipe in the photographs in the OP. So I am 100% sure that the plastic pipe in the OP is part of my plumbing system somehow.

The clean out port you are looking for should look like a plug in a 3 or 4-inch tee.
It is normally located at grade level around one foot from the exterior wall.

View attachment 364329

Do cleanouts for building drains always look like the white plastic pipe in the photograph that you posted on post #3 on this thread? I have not seen anything that looks like that in my yard.

I wonder if the cleanout for my building drain might be buried underground.

 

[Rive]

Do you think that the 1/2" or 3/4" diamater plastic pipe in the photographs above is the cleanout for my building drain?

Extremely unlikely. Some kind of overflow pipe, at most.

There is a 3" or 4" diamater plastic pipe coming out of my house at the back of my house. This 3" or 4" diameter plastic pipe coming out of my roof might be the stack. But there is no cleanout for a building drain directly below this plastic pipe that might be my stack.

Could you please takes some photos about that area?

Depending on the local code and customs, the cleanout(s) can be right next to the building: some feets away from the building: close to the property line: at every dozen meters inbetween, and of course: all of these at any variations... Code may change in every few years, but buildings stays as-is for decades, so you have to know all the previous variations of the relevant code => experience will be needed.

Look around in the neighbourhood and try to ask questions. Somebody will likely remember.

If it is a single house then you may try to draw a line between the maybe-relevant sewer access cover on the street and your bathroom, then look for clues there.

 

[russ_watters]

Do you have a basement or crawl space? My sewer pipes collect into a main in the basement and there is a clean out at the bottom of each riser.

That small pipe can't possibly be a clean out. It looks like my sump pump discharge.

 

[sandy stone]

To me it looks like the outlet of the water heater relief valve.

 

[sevensages]

Do you have a basement or crawl space? My sewer pipes collect into a lawn in the basement and there is a clean out at the bottom of each riser.

That small pipe can't possibly be a clean out. It looks like my sump pump discharge.

I don't have a basement or a crawl space. My duplex townhouse has a slab foundation.

 

[sevensages]

To me it looks like the outlet of the water heater relief valve.

That definitely makes sense to me because one time about 3 years ago, my pressure reducing valve, my T/P relief valve on my water heater, and the expansion tank on my water heater all became defective simultaneously due to a water surge, and water started pouring out of the plastic pipe in the photographs in the OP.


Where do you think the cleanout for the building drain would be?

 

[sevensages]

It just occurred to me that it might help for people here to know the age and location of my townhouse. Plumbers might have installed cleanout for building drains in different places in different times or different countries.

My duplex townhouse was built in 2001. It is in the United States of America.

 

[sandy stone]

Have you looked inside the house, near the base of the stack? There would normally be a cleanout where the pipe changes from vertical to horizontal. If the stack is near an outside wall, you might look outside, opposite the direction the pipe would take to the sewer line in the street.

 

[sevensages]

Have you looked inside the house, near the base of the stack? There would normally be a cleanout where the pipe changes from vertical to horizontal. If the stack is near an outside wall, you might look outside, opposite the direction the pipe would take to the sewer line in the street.

I have not looked inside the house because I don't know where to look inside the house. I think that my stack changes from vertical to horizontal somewhere in my attic. But that is over 10 feet above the building drain. So I don't see how the cleanout for my building drain could be in the attic.

I am in my semi-truck right now, not at my house. I am about 99% sure that there is only one plastic pipe that comes out of my roof. I think that that plastic pipe that comes out of my roof must be the stack because i cannot think of anywhere else the stack could possibly be.

Assuming that the plastic pipe that comes out of my roof is my stack, yesterday i did look for the cleanout for the building drain on the ground outside below the stack, opposite the direction the pipe would take to the sewer line in the street, and i did not see a cleanout. I wonder if the cleanout might be buried underground.

 

[berkeman]

After looking for a long time, I finally found the cleanout for a townhouse that we lived in (in the foothills above Silicon Valley). It was under a round concrete cover in our short sloping driveway (you can see it to the right behind my wife's bright orange car):

 

[jack action]

For some unknown reason, PhysicsForums rotated my photographs 90 degrees to the clockwise.

Post in thread 'Random Photos'

Apr 19, 2025

NoGood. I do not understand why.

You can rotate an image in two ways:

1. By actually rotating the image;
2. By inserting a "command" in the EXIF data to rotate the image when on display.

In the latter, some programs don't read those commands in the EXIF data, thus they don't rotate the image.

For example, I use your image and open it in one of my "image viewer" programs that I know rotates it with EXIF data when asked, and I overwrote the now "rotated" image. (Note that I converted your image to JPG because my "simple" program doesn't deal with WebP images.)

Then I open...

• jack action

• 

 

[sevensages]

My duplex townhouse is on a city sewer line, not a septic tank.

 

[sevensages]

My water meter is in my front yard close to the street in front of my house, while my stack is in the back of my house.

Does the fact that my water meter is in my front yard near the street mean that the sewer line would be in front of my house (as opposed to the sewer line running behind my house) also? If so, does that tell us anything about where the cleanout for the building drain would be?

 

[sevensages]

Photograph

You can see the plastic pipe coming out of my roof in both photographs. I think that that plastic pipe coming out of my roof in both photographs is my stack. In the more zoomed out photograph (the top photograph), notice the wooden fence at the bottom of that photograph. The outlet pipe to my T/P relief valve that is in the photographs in the OP is by that wooden fence.

Do you agree with me that that plastic pipe coming out of my roof is my stack?

 

[sophiecentaur]

Do you agree with me that that plastic pipe coming out of my roof is my stack?

It looks very likely. In UK, that large bore pipe would be a breather and usually in a vertical line with the large bore soil pipe which would have feeds from lavatories and other appliances. Is it situated virtually above the (or at least one of the) lavatory outlets?

Before we look further into possible solutions to this, could you describe the actual problem. Does the lavatory back up or empty very slowly or is it another small bore drain that is clogging. Is there audible gurgling from other sinks and basins?

It's very easy to approach these problems from the standpoint of ones favourite diagnosis without a thorough study of the symptoms. Drain installations can be modified by amateurs / cowboys who ignore / don't know best practice. Many useful access points are covered up with concrete and with no view to the future.

You could always try chemical methods. Concentrated sulphuric acid can work wonders. (take care, of course)

 

[Lnewqban]

Do cleanouts for building drains always look like the white plastic pipe in the photograph that you posted on post #3 on this thread? I have not seen anything that looks like that in my yard.

I wonder if the cleanout for my building drain might be buried underground.

See another type in the link provided in that post.
A flat bronze cover is used in areas where vehicles can run over it.
Yes, it is probably buried under vegetation and dirt.

The underground pipe leading to the point of connection with the main sewer pipe running below and along the street is normally located on the side of the house that is opposed to the water meter and the underground water supply pipe.

You should be able to see a round iron disc that covers another clean out port located at your property line along the street.
That should have stamped the Sewer fonts on it.

 

[Rive]

Do you agree with me that that plastic pipe coming out of my roof is my stack?

Yup. The first cleanout access point should be close to that pipe: maybe at the bottom of it, maybe just close: might be covered by drywall (with only a small door visible).
Like these:

=>

(source)

Or:

=>

Some may be on the floor:

 

[Nugatory]

After my pressure regulating valve, my T/P relief valve, and the expansion tank on my water heater became defective, a steady stream of water started leaking out of the plastic pipe in the photographs in the OP. So I am 100% sure that the plastic pipe in the OP is part of my plumbing system somehow.

That very strongly suggests that that pipe is the overflow for the water heater pressure relief valve.

 

[sevensages]

That very strongly suggests that that pipe is the overflow for the water heater pressure relief valve.

Yes. I have already confirmed that.

So where do you think that the cleanout is for my building drain?

 

[sevensages]

Yup. The first cleanout access point should be close to that pipe: maybe at the bottom of it, maybe just close: might be covered by drywall (with only a small door visible).
Like these:
View attachment 364365 =>View attachment 364366
(source)

Or:
View attachment 364367=> View attachment 364368

Some may be on the floor: View attachment 364369

I am back in my semi-truck now. So I cannot go check. But I have lived in my house for 11 years. The stack is directly above my bedroom. I don't remember seeing any access door inside my bedroom for a cleanout for the building drain.

 

[Rive]

The stack is directly above my bedroom.

All I know is where would I look.
Might be covered up during a renovation?
Or just on the other side of the wall?

On this picture:

The marked parts looks suspicious too.

 

[sevensages]

All I know is where would I look.
Might be covered up during a renovation?
Or just on the other side of the wall?

On this picture:
View attachment 364395
The marked parts looks suspicious too.

All there is behind that insulation cap is a water faucet, not a cleanout. I know that because I am the person who installed that insulation cap.

When you say "The marked parts look suspicious too", do you mean that area you put in a red colored rectangle looks like there might be a cleanout behind it?
--------------------

Edited to add: I am viewing the photo on a cell phone with a small screen. At first, I had no idea why you inserted that red colored rectangle there. But then I looked at the photo in my gallery on my cell instead of looking at the photo via this message board. I was able to zoom in the photo when I looked at it in my gallery. I now see the two vertical cracks or lines in that wall. Do you think that my cleanout might be behind there? The area of that photo that you put in the red rectangle is about 25 or 30 feet to the side of my stack.

 

[Rive]

Do you think that my cleanout might be behind there?

No idea, but it looks like there was some happenings with the foundation there. And at this point it's already a detective story, so every clue counts.

It's very limited what we (on this forum) can do with limited information. What I would do there is, to check and re-check those walls where that pipe may go down. Inside and outside, in every detail, because the first access point is supposed to be around there.
I would also ask (well: look) at the neighborhood.

 

[Averagesupernova]

The clean-out in a house with a basement is always at the beginning of the horizontal run that goes to the sewer main which is usually under the street. However, most but not all drain pipes go into the floor vertically and then turn horizontal under the floor so the clean-out is usually a Y fitting just above where the stack goes into the floor. They may also have a clean-out coming out of the floor right next to outside basement wall. Just another place to access. There are often secondary pipes going into the floor say for instance a kitchen on one part of the house with a bathroom on a different part of the house. Both horizontal runs need to have clean-out access.
-
In your case you need to think about how the basement scenario would adapt into a slab scenario. There is nothing to say that the clean-out couldn't be on the opposite side of the house of the sewer main. So possibly in the back yard if the sewer main is under the street. If the main stack and the secondary go into the floor then it is conceivable that a clean-out could be arranged so that it catches both horizontal runs at the same time. I've worked very little with slab DWV systems. My experience is basements. In any case don't expect the clean-out to be someplace where the snake would have to turn a bunch of corners to get all the way to the city sewer main.

 

[berkeman]

Depending on the local code and customs, the cleanout(s) can be right next to the building: some feets away from the building: close to the property line: at every dozen meters inbetween, and of course: all of these at any variations... Code may change in every few years, but buildings stays as-is for decades, so you have to know all the previous variations of the relevant code => experience will be needed.

My duplex townhouse was built in 2001.

That's pretty recent construction. Since you mention townhouse, is this part of an HOA? If so, you may be able to learn more about the construction from the HOA, and maybe even get access to the original plans for the construction.

When you purchased the townhome, was there a home inspection done? If so, the report may make note of the cleanout location, since homes that do not have a cleanout already are typically more expensive for plumbers to clear stoppages (like if they have to go through the roof access). If you are renting the townhome, you could check with your landlord to ask if they had a home inspection done when they purchased it.

 

[sevensages]

It's very limited what we (on this forum) can do with limited information. What I would do there is, to check and re-check those walls where that pipe may go down. Inside and outside, in every detail, because the first access point is supposed to be around there.
I would also ask (well: look) at the neighborhood.

You can see a photograph of the side of my house and my stack in post #17. You can see that my exterior walls have siding.


Do you think that the cleanout for my building drain might be on the exterior wall below the stack and underneath the siding?

 

[Rive]

Do you think that the cleanout for my building drain might be on the exterior wall below the stack and underneath the siding?

I do not 'think'. I only see it possible.
Certainly, hasty renovations can make a mess out of a house.

 

[sevensages]

Update: the Homeowner's Association for my neighborhood has a facebook group. I asked the members of the facebook group for my neighborhood where the cleanout for the building drain is on their properties, and I got two replies that answered the question (and several other replies that do not answer the question).

One person said that her cleanout for her building drain is in her tree ring, which is in the middle of her front yard. The other person said her cleanout for her building drain is in her flower bed, which is also in the front yard, but the flower beds are right next to the houses (as opposed to the middle of the front yard). So I think my cleanout is probably buried underground in my front yard somewhere. Before I created this thread, I thought my cleanout was probably in my bard yard near my stack.

 

[berkeman]

Yikes! Buried and unmarked?

 

[sevensages]

Yikes! Buried and unmarked?

I think so.

 

[Averagesupernova]

Interesting. Both neighbors say in the front yard. That implies that the city main is on the opposite side of the house. Unless the clean-out is only concerned from that point to the street.

 

[sevensages]

Interesting. Both neighbors say in the front yard. That implies that the city main is on the opposite side of the house. Unless the clean-out is only concerned from that point to the street.

When you say, that implies that the city main is on the opposite side of the house, do you mean that that implies that the city sewer main is on the opposite side of the house?

 

[Averagesupernova]

When you say, that implies that the city main is on the opposite side of the house, do you mean that that implies that the city sewer main is on the opposite side of the house?

Uh, yeah that's what I said. To be a clean-out for the "building" as you put it, it is implied that the snake goes into the clean-out, under the house towards the city main. I would have assumed the city sewer main is under the street. Of course that could be an incorrect assumption.

 

[Lnewqban]

The 3-inch sanitary drain clean-out port is normally located at grade level, as close to the exterior wall as possible, in order to reach farther into the house, but not closer than one foot, so the plumbing snake can be easily fed also into the sewer main direction (commonly, there is a 2-way tee connecting the clean-out vertical pipe and the underground drain pipe).

Please, see:
https://up.codes/s/cleanouts-for-drain-piping

Regarding location of underground water supply, storm and sewer main pipes, could the underground layout be like this?

 

[sevensages]

Uh, yeah that's what I said.

You just wrote "city main". You did not write "city sewer main".

To be a clean-out for the "building" as you put it, it is implied that the snake goes into the clean-out, under the house towards the city main.

I am not a plumber, but if the city sewer main is under the street in front of my house, I don't see why it is impossible for the snake to go into the cleanout, and go through the building drain towards the stack, under the house AWAY from the city sewer main.

I would have assumed the city sewer main is under the street. Of course that could be an incorrect assumption.

I don't definitely know where the city sewer main is, but I think the city sewer main is probably under the street.

 

[sevensages]

The 3-inch sanitary drain clean-out port is normally located at grade level, as close to the exterior wall as possible, in order to reach farther into the house, but not closer than one foot, so the plumbing snake can be easily fed also into the sewer main direction (commonly, there is a 2-way tee connecting the clean-out vertical pipe and the underground drain pipe).

Please, see:
https://up.codes/s/cleanouts-for-drain-piping

View attachment 364481

Regarding location of underground water supply, storm and sewer main pipes, could the underground layout be like this?

View attachment 364482

Yes. The underground layout of my sewer line and water line could be like that. Indeed, I think that the underground layout of my sewer line and water line is probably like that.

 

[Averagesupernova]

I don't see why it is impossible for the snake to go into the cleanout, and go through the building drain towards the stack, under the house AWAY from the city sewer main.

Because it would not clean anything between the clean-out and the city main. Post #37 shows a solution to that problem. As I previously stated my experience is with basements. The clean-out is at the beginning of the horizontal run in that case and can extend all the way to the city sewer main.
-
Whatever course you took could be well complemented by a few good books from a home improvement center or the appropriate section in a good bookstore. There are some really good books out there and some not so good books. You will have to sift through them until you understand everything.
-
My state has a homeowners plumbing permit option for those who want to do their own. They supply a crude yet very effective guide concerning DVW rules. A bit confusing at first but after absorbing it all, it made a lot of sense.

 

[sevensages]

Because it would not clean anything between the clean-out and the city main.

But it would clean everything between the clean out and the stack.

Post #37 shows a solution to that problem.

Yes. Or the perhaps one could feed the snake either way through the clean out.

As I previously stated my experience is with basements. The clean-out is at the beginning of the horizontal run in that case and can extend all the way to the city sewer main.
-
Whatever course you took could be well complemented by a few good books from a home improvement center or the appropriate section in a good bookstore. There are some really good books out there and some not so good books. You will have to sift through them until you understand everything.
-
My state has a homeowners plumbing permit option for those who want to do their own. They supply a crude yet very effective guide concerning DVW rules. A bit confusing at first but after absorbing it all, it made a lot of sense.

 

[gmax137]

A neighbor had their sewer line back up into the house, a huge mess. The cleanout ended up being under the front patio, which has a paver floor. The location wasn't discovered until other neighbors were consulted; they had been there when the previous owner built the patio. At least pavers are easier than jackhammering concrete.

 

[berkeman]

The location wasn't discovered until other neighbors were consulted; they had been there when the previous owner built the patio. At least pavers are easier than jackhammering concrete

What kind of a dimwit covers up a cleanout with patio pavers... Lordy.

 

[Averagesupernova]

What kind of a dimwit covers up a cleanout with patio pavers... Lordy.

The same dimwit who covers up a silcock under a deck with a composite floor. An observant individual such as myself concerning this sort of thing noticed a short piece of decking (composite, not cedar) that was not attached. It just set in there. Upon removal I noticed the silcock. Makes me wonder if the same brainiac installed another silcock over one of the window wells.

 

[gmax137]

Lordy.

Indeed!

 

[Herman Trivilino]

Before I created this thread, I thought my cleanout was probably in my bard yard near my stack.

That's likely where it is. Probably just below grade. Poke around with a shovel.

 

[Herman Trivilino]

What kind of a dimwit covers up a cleanout with patio pavers... Lordy.

Uhhh... I did that. :-). But all you have to do is remove that one paver and the cleanout is a fraction of an inch below. I've had to access it a few times and it's easy. You just have to know how to find it. :-)

 

[berkeman]

You just have to know how to find it. :-)

This. Maybe engrave that one paver with "Cleanout"...

 

[Herman Trivilino]

This. Maybe engrave that one paver with "Cleanout"...

Like the OP, my house is a slab on grade building. I really should engrave the side of the slab with "1.5' to clean out".

 

[sevensages]

That's likely where it is. Probably just below grade. Poke around with a shovel.

Please look at the photographs I posted on post #17. Notice that my concrete patio is directly below my stack. So I cannot poke around directly below my stack with a shovel because that area is concrete.