I really hope someone can help me figure this out.

We live in a midrise condo (middle floor) and for years (on and off), when a unit in our stack (most likely upper unit somewhere but now we aren't so sure anymore) does the laundry, their laundry soap foam ends up in our toilet accompanied by loud gurgling & bubbling noise. The whole event starts with gurgling and bubbling of water in our toilet bowl and ends up with the laundry soap foaming and filling up the toilet bowl.

Some days it is just loud gurgling and bubbling. Some days it is gurgling and bubbling with laundry soap filling up the toilet bowl. And some days it could be either scenario mentioned with the entire bowl emptied out at the end on its own without anything done on our part.

To me, it seems logical to think that someone's laundry water & soap enter the common shared vertical washer drain stack, it cannot continue its path due to some sort of obstruction (debris and/or trapped air?), and somehow enter common shared vertical toilet sewer stack to end up in our toilet.

Can someone please share their knowledge and insight because this is beyond frustrating with years of management's NON-management. I can share more details if anyone wants/needs to know.

Thank you.



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It makes sense that that a drain/vent pipe a clothes washer and your toilet share is blocked somewhere below your toilet. An interesting test would be to block your toilet when this is happening. The water should come out in the next-lowest device in the stack - your bathtub? If this were a house you'd go to the roof and run a snake down the drain. If the association were doing its duty it would.

Does your unit have access to a cleanout? You can run a snake it yourself. You can buy a 25-foot snake for not much at Mallwart, etc. You can run it through your toilet. If you are determined you can unmount the toilet for better access. Replace the wax ring with a Fernco FTS.


If the drain is completely blocked your toilet won't flush, so it must be only partially blocked, enough to slow down a clothes washer's effluent.

It's possible that you're responsible for causing the blockage. I'm not blaming you, but pointing it out. Stuff gets flushed by mistake.

Perhaps one of those enzymatic cleaners, such as Green Goblin, would help. I've never used. If it's goop it could; if it's a diaper it won't.

Is there a significance in replacing the wax ring with what you are recommending?

This occurrence happens completely randomly and suddenly that there is no way to test anything. Sometimes it happens within days. Sometimes there are weeks between incidents. Sometimes there are months between incidents.

Even tracing the source unit took a very long time because of management’s dereliction of duty. I thought I confirmed the source (with the actual owner right after one incident). But sadly the owner passed away not too long ago and this has happened twice since. Management insists there is nobody living in that unit since the owner’s passing so now I have no idea what is going on.

The Fernco FTS is a better product and reusable. I had problems with my toilet, am happy that I didn't have to deal with a new wax ring every time I took it off. It isn't necessary. If you end up taking the toilet off a few times you'll have a better experience.

If it is a clog then it should happen when anyone above you does the laundry. Is there more than 1 unit above? Maybe if it's only the unit directly above and water from higher units is going fast enough...

Why it's intermittent and so rare is a bit of a puzzle. Perhaps the clog builds up slowly then breaks only to build up again.

Does your clothes washer use the same drain? It's 'above' the toilet isn't it?

Thank you so much for replying to my posts. Greatly appreciated!

We are on 3rd floor. When I contacted the units above me that are on my stack one day of the incident (summer 2025), the source unit was found to be on 6th floor (final floor). And he actually told me that his unit was the one that did a “test run” with a former assistant manager who was trying to help me a few years prior. And that test run day indeed produced the result we’ve been having. But we never knew the specific unit number; former assistant manager never told us. The owner was just advised not to use too much soap.

But since it kept happening and we didn’t know the unit number, we were stuck. All subsequent managers were absolutely unhelpful.

Our condo unit is one level so our laundry room and main bathroom are on the same floor/level. As for sharing the same washer vertical drain stack, I am not certain 100% since 6th floor layout is different from our floor plan. But looking at the architectural floor plans of 6th and my floor, laundry drain seems to lay either very closely or actually share one. And if that is the case, the laundry drain stack and my toilet drain stack are only a few feet apart.

Anyway here we are today and one of my wonderful neighbors pointed me to forum, hoping other homeowners and plumbing professionals could share insight and knowledge with me.

suds relief is what is to be addressed and what that is is that the vent from a suds producing fixture shall have a branch line of a specific length to avoid what you are experiencing. 711.1 Chapter 7 Uniform plumbing code. Drainage connections shall not be made into a drainage pipe system with in 8 feet of a vertical to horizontal change in direction of a stack containing suds producing fixtures. Bathtubs, washing machine stand pipes, kitchen sinks and dishwashers shall be considered suds producing fixtures. Some one screwed up or some neighbor is using an excessive amount of soap. the change in direction in the pipe causes suds because changes in direction from vertical stacks to horizontal branch lines or main building drain cause suds. That is why 8 feet is required. Now someone may have screwed up. Plumber or some plumber that should be referred to as apprentice. It may have been structural to cause the connection to have to be closer then 8 feet but without doubt there is some kind of issue with the piping. Not a lot you can do about it.

May also be an offset near your branch line into the stack.

Just don't pop the bubbles with your tongue. May not be sanitary.

The whole of 711.1 (Suds Relief) is revealing:

Drainage connections shall not be made into a drainage piping system within 8 feet (2438 mm) of a vertical to
horizontal change of direction of a stack containing suds-producing fixtures. Bathtubs, laundries, washing machine standpipes, kitchen sinks, and dishwashers shall be considered suds-producing fixtures. Where parallel vent stacks are required, they shall connect to the drainage stack at a point 8 feet (2438 mm) above the lowest point of the drainage stack.

Exceptions:
(1) Single-family residences.
(2) Stacks receiving the discharge from less than three stories of plumbing fixtures.


So they could have been following the rules for a shorter building.

I found this explanation:



The above-named suds producing fixtures discharge high-sudsing detergents that, when mixed with other liquid wastes (in addition to air in a stack), create areas of increased turbulence in lower portions of soil stacks. The liquid wastes, being heavier than suds, will flow through the suds-loaded piping without carrying the suds discharge along with the flow (see Figure 711.1a). However, the suds become compressed, forcing them to move through any available path of relief. The relief path may be any of the branches connected to the building drain or a vent stack or branch vents. High suds pressure will blow trap seals, leaving residue in the fixtures and allowing sewer gas to enter the building (see Figure 711.1b). Any vertical-to-horizontal change of direction of a stack receiving the discharge of suds-producing fixtures has the potential to create a sudsing problem.

I’m grateful for your responses (both of you) but my plumbing knowledge is exactly 0 and honestly i cannot wrap my head around what is being said here.

With that said, when a plumbing company was sent by the management, after some testing** they ran, descaling main stacks/lines (from the garage where all pipes are exposed) was recommended and it was supposed to happen. It never materialized. Would that have helped?

What about utilizing the cleanouts (which I assume would be in the garage somewhere)? What could they do with the cleanouts and would that help?

**testing consisted of a plumber observing the toilet in my unit while his colleague went to the unit right above me and ran dishwasher, clothes washer and flushed toilets. The plumber in my unit observed some gurgling and bubbling (although no suds and not as extensive as what we experience but still there was something). They determined descaling would help with drainage. Descaling was explained to me as something more heavy duty than simple snaking.

Thank you again for your replies.

My first posts were wrong. Your problem would seem to have nothing to do with a clog. I've never worked on plumbing in a building so tall so I didn't know about the suds relief issue.

Mechanic77777 seems to have it right. If so, the solution is to increase the length of the horizontal pipe that connects at the bottom of the unit that causes the problem, which seems unlikely. Possibly that unit's drain can be re-routed, if there's an alternate route that would be long enough.

The next part of the code on suds relief is about testing. If a test shows that the drain doesn't meet code the county/city could cite the condo. If they have to dig up the pipes fixing it would be a serious undertaking.

50 years ago one used a cup of detergent. Today one uses 3 tablespoons. Many people, used to the old ways, use too much. Advice columns suggest washing towels with no detergent just to clean out the built-up soap. It wouldn't surprise me that, if you could get the people upstairs to use the right amount of detergent, or pods, that you wouldn't have the problem. That's unenforceable. If I had built a 4-storey house and put the laundry on the 4th floor, and neglected to make the horizontal leg of my drain pipe long enough, that's what I would do.

FWIW some think this part of the code has been made unnecessary but front-loading washers: [www.proventsystems.com] I don't see that in the current code myself. Perhaps I missed something; perhaps this is false.



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Good morning. Thank you for your reply.

The days where we get only loud gurgling and air bubbles in our toilet water (zero suds), does the faulty/incorrect suds relief system still apply here?

Thank you.

Yes. The symptom can be just air and sewer gas. I found a colloquy in plumbingzone that commented on the possible difficulties of repairing this problem. One added check valves, claimed they had worked so far. [#$%&]

Is Plumbingzone another forum like this one?

If so, how would I find the discussion thread you are referring to? What key words did you use to find that discussion and adding a check valve? I will Google further for an explanation for a check valve in this situation but if you don’t mind, can you clarify it in the simplest terms?

Thank you again.

Ok, I just went to Plumbingzone and I can’t sign up to post my problem because it’s for plumbing professionals. Bummer.



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Do you see that [#$%&] ? That's the URI of the article to which I referred, apparently blocked. /threads/ suds-problem.1496/ at plumbingzone . com - remove the spaces.

Are you a tenant or the owner in this condo?

Is this issue of your toilet gurgling and bubbling present when you first moved in or is it something that developed over time?

Is this issue something all your neighbors are experiencing or just you?

Because if the issue is related by incorrect/bad piping, it would occur on day one, and to many units. If you want to dig down that road, you could try to find original construction records at your city's building services and records, all of this should be public records. There should be some kind of isometric of the DWV system that you can review to see the original layout is problematic. Yes there are sudsing consideration in high rise plumbing but I have never seen fixtures that produce suds such as a dishwasher, a tub, a shower or a washing machine being laid with that consideration in mind. A dishwasher for example, most of the time is not even drained via a dedicated drain in a mid or high rise commercial building they just connect to the disposer and drain via the kitchen drain, suds and all. Sometimes people don't drain their washing machine into a drain directly, they have a laundry sink and they just discharge into the sink and water runs into the sink drain.

If it's something that happens to a few units, yours and someone else, that it suggests that there is something else that is at play here. A partial blockage, someone using the washing machine incorrectly or something else.

If there is a partial blockage downstream of you, the upstairs discharge can run down and hit this blockage and has no where to go but back into the branches. If you are getting water with detergent into the toilet, this is flow backing up into your unit. This flow contains both fluid and air, and the air causes the gurgling sound. Is it also backing into your tub or shower or no?

You mentioned the HOA has previously investigated this but did not follow through? What does this mean? Is there someone at the HOA that deals with this, or is there a management office that handle these matters and is incompetent? If you are the owner, you have the rights to request a report of that process...who was hired, what did they find out, what is the next step, and why was it not followed up? Is it lack of funds or incompetence?

You said they mentioned "descaling" as an option...does this mean these pipes are cast iron? I have seen cast iron pipes with severe restrictions from build up but these are usually relatively older properties or in cities that still require cast iron pipes in commercial buildings. Do you know what kind of piping materials your DWV system is? Plastic (like PVC or ABS) or metal?

If you look at the floor plan of your unit and the one above, and below, I assume all floor plans are similar? Their washing machine is the same as yours?

Have you considered the possibility of this discharged water is not from your upstairs neighbor but from someone on the same floor? Many condos have units that are mirror images. For example units A & B may be the same layout but mirror image and they share a plumbing wall, and on the other side of your washer is another washer of the adjacent unit, your bathroom is next to theirs. Sometimes these units have drains that merge inside the common wall cavity before they reach the main drains. This is especially common in buildings that used to be hotels, or multi-family rental dwellings that were converted into condos for individual resale.

Another possibility is someone is not using correct detergent and creating excessive suds. Modern day machines use HE detergent and has less suds, and use less water as well. If someone is still buying non HE detergent and using it in machines that requires HE detergent, this could be a problem.

Finally, there is not a lot you can do as an owner to solve a problem that is not within your space. You need to lean on the HOA and nudge. I would start with going back to get information about the previous investigation and why it is not followed through, be assertive and explain that this is really an issue that is bothering you for some time and "I am worried about the health of my family due to sewer gas being randomly expelled into my bathroom from somewhere else and this IS a health hazard, if you are not able to help in resolving this, can you point me in the right direction who to ask? Does the city's building department or the health department have inspectors that are experienced in diagnosing this issue?". Yes, sewer gas entering a living quarter is a health hazard and should not be brushed under the rug.

The other option to take, perhaps in parallel, is to attend a HOA meeting, and at the meeting ask the other owners present who else is experiencing these issues. To be proactive, ask the HOA to send a letter to each and every unit to see if they have similar issues and have a form where the owners can respond...this will allow you to see who else are having this issue or only you. If there are not a lot of units, you can ask HOA if it's OK for you to make your own form and go around and tape one on each door on each floor and have the form returned to your mail box in the lobby or a special box or the management office.



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Thank you for your response.

We are the owners. This issue started happening about 2 months after we moved in.

As I explained in previous threads above, this incident can happen every few days, every few weeks or even every few months. The longest we went without an incident was about a little over a year.

The incident can be described these ways:

(1) loud gurgling and bubbling in our toilet water in the beginning, then suds appear (still with gurgling and bubbling), more suds coming up and creating a massive foam (mixed with our toilet water) that either stops before the toilet seat or sometimes overflows the bowl.

(2) loud gurgling and bubbling in our toilet water but no suds appear.

(3) incident 1 or 2 happens and sometimes the entire bowl gets emptied (sucked) out on its own at the end of the incident.

(4) either incident can last under 10 seconds to about 2 minutes.

And this only happens in our main bedroom toilet and nowhere else (no sinks, no tub, no hallway toilet).

On our stack, we are the only ones with this issue. We are on the 3rd floor. But a few years back, I know something very similar happened to another unit but I don’t know which unit she lives in (it was a post that she wrote on our complex forum). I meant to follow up with her but I failed to do so.

When a former assistant manager was able to track down the source a few years ago (after inquiring who was doing the laundry on my stack), the resident was advised not to use too much detergent. But it kept happening but since I didn’t know which unit it was (and that assistant manager left by then), all I could do was to ask subsequent managers to check the laundry usages at the times and dates I indicated. Basically every manager failed to deliver.

I found out on my own which unit it was last year. The owner and I talked and he said since the former assistant manager’s advice from years ago, he said he has been using very little laundry detergent.

Getting any answers from all the different managers we had here since the assistant manager is a huge obstacle in itself. They either ignore you or they will not answer direct questions.

When our toilet room drywall was cut out once before, I saw the vertical drains stacks were PVC. But we have an underground garage where all the pipes are exposed near the garage ceiling and I know there are cast iron pipes. I am not 100% certain right now if ALL exposed pipes are cast iron but I do know the big, fat ones (I don’t know the proper name but I believe they are the ones that connect to the city lines?) that run parallel to the garage ceiling are cast iron.

The floor plans of this building is so peculiar. First floor units are two-story high with a very different layout than ours. In fact, our unit sits above two separate first floor units. So the problem toilet and main bedroom sit above one unit and the rest of our house sits above a different unit.

Then my floor, 4th floor and 5th floor all have the exact same layout.

And 6th floor (top floor) is another two-story units with a different floor plan than ours. And just like the first floor, our unit sits below two separate 6th floor units. When I tracked down the unit doing the laundry when an incident happened last year, it was on the 6th floor. His laundry room sits above our problem toilet & main bedroom side (not exactly right above our toilet room but very close enough).

The current management keeps referring to this as a unit-to-unit issue, it has nothing to do with the HOA and HOA is not responsible (they have seen the video I recorded of one of the incidents).

What I don’t get is: yes, the suds leave someone’s unit —> travel down the common vertical drain stack (HOA’s responsibility) —> suds fail to continue the path of common stack drain due to an obstruction/fault of some kind —> then suds somehow travel up the common toilet sewer stack (HOA’s responsibility) —> suds (or sometimes just sewer air) end up in our toilet.

How is this a unit-to-unit issue? Isn’t the common washer drain stack failing somewhere for this to happen? Or the problem can be the *main* building pipe where all pipes meet since something from common washer drain stack is ending up at common toilet sewer stack?

It’s so unreal how little work and effort they put into this in the past and continue to do so.

Is my logic above actually illogical?

Thank you for reading.

I understand your frustration, and it seems that management is not keen on resolving this. When you referred to "management" are you talking about the HOA management which included the officers or are you referring to the entity they hired to manage the day to day operations of the condo? Who is not responsive to your complaints.

Seems you have a few things you can do.

(1) Escalate the issue. Either bring the issue to the HOA officers by attending an HOA meeting, or have a direct talk to one of the officers about this and ask what you can do to get this investigated seriously. Keep mentioning that this is a health hazard to have sewer gas entering your living space and your bedroom toilet is getting siphoned dry by negative pressure or gas bubbling caused by positive pressure.

(2) This is a HOA responsibility because the problem is caused by someone/something outside of your unit. The cause of this is really not yours to find out, it could be a partial blockage downstream, it could be defective plumbing, it could be wrong detergent being used, it could be a combination of things. In a condo, you own the space defined by walls, ceiling and floors, so once it is outside of your space, it is HOA. Even the wall cavity between two units are HOA common elements. It doesn't matter if this issue is caused by someone upstairs, someone adjacent or someone downstairs, it is HOA jurisdiction, and not a unit to unit issue.

(3) You mentioned this is completely intermittent and it could be days in between episodes or months. This is going to be tricky because it cannot be reproduced on demand. So if they were to hire a plumber to come out, and nothing happens when he comes out and they would just say "see, we just wasted $$$ to troubleshoot nothing..." So there needs to be some homework done so this can be realistically tracked down. Have you tried:

(a) write down the date/day of the week/time when it happened? That could possibly provide a clue on some pattern?
(b) it could also be a combination of events. For example, it may not happen when the unit upstairs do a wash, but it could happen if the unit next door AND unit upstairs both do a wash around the same time and the combined effects caused this, which could explain the random nature of the occurrence. It could also be a washing machine plus a dishwasher, as both are suds producing.
(c) you mentioned someone posted this issue to the complex...is this something you can leverage? Can you post your issue and ask if anyone else have this same issue?

I agree with what you are saying.

In the beginning, all my reporting (and all dates, times, activities are being tracked by me since day 1 and every incident has been reported to all property management managers in charge at that time) was done to the property managers only. Then the HOA board was looped in 2 managers ago (in 2024). But the management abruptly terminated its contract with the HOA and the whole thing was up in the air until a new management came on board.

When the new manager appeared (2025), the decision was made for descaling after the plumbers did an experiment with the unit right above me (by running that unit’s washer, dishwasher and flushing toilets). We were told descaling schedule would be forwarded and we waited. Then we were informed the plumbers would do something else involving the unit above us a few months after we were informed of descaling decision.

We were not told what was done and we thought all was good since we didn’t have incidents.

Then that manager resigned and we got a new manager yet again (2026). After some back and forth (we had a couple of incidents since the new manager came to work in the beginning of 2026), we are being told to get a licensed plumber to inspect our own plumbing lines (which we are doing to prove that the problem is not the drains that exist in our unit) and it will be escalated after the inspection is done.

Anyway I immensely appreciate everyone’s replies, help and time here.

Thank you so much.



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