Condominium sewer line overflow skipped one unit in row

[Henry Ramsey]

Hey all, I live in a condo in Houston. These were built in about 1971 as apartments and resemble townhomes rather than condos.

The units are three sizes:
3 bdrm w/ 2 full separate bathrooms up, 1/2 down
3 bdrm w/ 1 sink+commode - tub - sink+1 commode up (hollywood bath), 1/2 down
2 bdrm 1 full bathroom up, 1/2 down

We have full gamut of 1970s construction; aluminum wire, FPE breaker boxes, galvanized steel water lines and cast iron sewer main. There are 30 units total in four buildings which share the sewers in parallel pairs and each dumps into city street sewer separately. The units 30 units. #1-15 on one side and #16-30 on the other. There are clean outs at the rear end of each and in the middle of only one side. The rear of the property backs against Addicks Dam.

I'm the association president and defacto manager so all issues big and small come my way.

This is a doozy though:

On January 7th at around 3:30 PM I got a knock at my door that unit #21 had their toilet over flowing. I went to the unit to find it was not just over flowing it was *running* over.
I asked the next unit resident toward the street #22 if they were having problems and they had none.
concluding a sewer clog from #21 to #16 I went looking to see who was home so I could see who else had problems. Nobody else was home yet it was only 4pm, but walking around I found the cleanout at the Dam end which is also the end of the sewer line was bubbling and water was coming up.

In front the 5 of the 6 units #16-19 had evidence of water coming from under their doorways.
I got a pipe wrench and opened the clean out which relieved the pressure of the over flowing toilets.
All the overflows ceased.

When people got home we began clean up. The HOA had the sewer line snaked that night and the plumber found 1/2 dozen tampons amongst other stuff. The issue recurred the following Saturday and the plumber came and roto rooted the sewer line again. We have since had both sewer mainlines jet washed.

Now, after that long summary I have two questions:

1) Why would the water overflow in the sewer main that cause 5 units toilets SKIP one in between?

The unit that initially had the water flowing #21 was the front end of the clog (unit #22-30 were wholly unaffected), but the very next unit #20 was skipped. After that all four units #19-16 to the end of the sewer line flowed over.

What is up with that? Is that normal? Is there something wrong in that unit that stopped it from clogging but perhaps also contributed to the main sewer issue?

2) And why are toilets in only a couple of units still bubbling?

Unit #19 they had a secondary clog at their sink which was snaked, but the toilets are now bubbling and began doing so before the initial clog issue. When they flush upstairs the downstairs toilets water moves
and gurgles.

At one point someone suggested the latter issue with bubbling *was a vent issue*, but a plumber I trust who knows our plumbing said not. He said we have three outlets each unit into the main; toilets, upstairs, and laundry+kitchen sink. Each is separate connection to the sewer main and should be cleaned routinely.
His opinion too was we just need new sewer connections due to age.

Also, there are individual vents on each unit. Two or three pipes depending on size. Most units have their A/C mains drain into the drain behind the bathtubs with an overflow pipe from the attic pans that leads outside.

Unit #20 which has thus far been skipped now has low water level in the toilet after they flush.
Is that a coincidental but unrelated issue perhaps?

I'm sorry for being long winded.

*Edited to add complete sentence above. *

 

[Reach4]

Normally the toilet is not the lowest drain. A shower or tub usually is.

1) Why would the water overflow in the sewer main that cause 5 units toilets SKIP one in between?

The unit that initially had the water flowing #21 was the front end of the clog, but the very next unit #20
was skipped. After that all four units #19-16 to the end of the sewer line flowed over.
What is up with that? Is that normal? Is there something wrong in that unit that stopped it from clogging but perhaps also contributed to the main sewer issue?

#20 may have had its toilet at a higher altitude. Maybe no basement when the others had basements. Wait... no basements in Houston.

#20 may have had a working sewer check valve. Working swinging gate check valves are rare, but possible. It is also possible that #20 had a superior check valve.

If sewer flooding is common there, #20 could even have had a pump installed which saves #20 at the expense of the others.

2) And why are toilets in only a couple of units still bubbling?

Bubbling is weird. That sounds like air coming up, and with vents, there should be no way to have significant air pressure in the lines.

I am not a plumber.

 

[Sponsor]

 

[Henry Ramsey]

Normally the toilet is not the lowest drain. A shower or tub usually is.


#20 may have had its toilet at a higher altitude. Maybe no basement when the others had basements. Wait... no basements in Houston.

#20 may have had a working sewer check valve. Working swinging gate check valves are rare, but possible. It is also possible that #20 had a superior check valve.

If sewer flooding is common there, #20 could even have had a pump installed which saves #20 at the expense of the others.


Bubbling is weird. That sounds like air coming up, and with vents, there should be no way to have significant air pressure in the lines.

I am not a plumber.

The toilets up and down are connected what ever size pipe is normal for toilets 3" and that is PVC in the walls. The laundry areas are open to the downstairs 1/2 baths or to the kitchen.
In the wall where the laundry plumbing is the pipe from upstairs drains.
Then the laundry outlet goes under the kitchen floor and joins into the pipe under the sink.

No basements in TX in general so far as I know. We had the main sewer camera checked which revealed no breaks or issues that could be seen from the camera. The way I understand it though there can be clogs at the inlets from each unit's connection to the main that a cam check of
the main would not reveal.

No check valves in these units at all unless it's added secondarily. If one had it then all would. They have not been remodeled since 1976 when
they were converted from apartments to condominiums. Unless someone tore open the floor in that one unit and added one sometime in the
past which would require a lot of work since we have no rebar, but instead have 2" aggregate stones in the slab. And no pumps of any type. The unit is rented and the renter did not even know anything was wrong until we asked her to check for water of which she found none and Servpro which we hired for clean up found no moisture in her floor (laminate).

*I did not complete my sentence before about the bubbling. I thought it was venting perhaps a clogged vent pipe, but the plumber
I know said not. I edited my original post.*

 

[Reach4]

Is the rim of the overflowing toilet below street level? I would consider pulling a manhole cover for the city and looking inside.

Is the overflowing toilet rim the lowest outlet in that unit-- lower than a shower or tub drain?

I am also thinking maybe contacting the sewer department of the city could be a good idea. They usually try to be helpful and have expertise. Maybe they have a lift station that is not doing its job.

 

[Henry Ramsey]

Is the rim of the overflowing toilet below street level? I would consider pulling a manhole cover for the city and looking inside.

Is the overflowing toilet rim the lowest outlet in that unit-- lower than a shower or tub drain?

I am also thinking maybe contacting the sewer department of the city could be a good idea. They usually try to be helpful and have expertise. Maybe they have a lift station that is not doing its job.

No. These toilets are at first floor grade. No showers or tubs on first floor. All tubs are upstairs.
They are no longer over flowing that issue was relieved in January. The issue now is this odd bubbling which the unit
owners said began before the initial clog and though that was both cleared and the sewer main jet washed it still bubbles.
Today they are having the toilet line roto rooted for whatever that is worth to them. Paying for it from money they got fromtheir insurance
for the damaged caused by the toilet overflow. Since the rebuild of their walls and flooring replacement is to begin Monday- and they will not be
home since the insurance is also covering a hotel while they have it all repaired- they are necessarily concerned of the same thing happening again since their insurance gave enough of a time to pay out this time. The main sewer clog is gone so any overflow would be local to their unit.

The city main is probably not the issue. And they will not help with private property.

 

[Reach4]

The city main is probably not the issue. And they will not help with private property.

While they may not help with work, they may help with pretty good advice for free.

Let us know the outcome.

 

[Henry Ramsey]

While they may not help with work, they may help with pretty good advice for free.

Let us know the outcome.

Sadly this is City of Houston we're talking about and they will not under any circumstances talk with us about an issue
in our private sewer line. All they will say is "call a plumber".

 

[Terry]

I think I would camera all of the lines now. Don't wait until the restoration is complete. The gurgling doesn't sound good. I doubt that it's venting, but it could be water left over in the drain lines, and if so, why? If concrete needs to be broken, it's better when the units are vacant.

 

[Henry Ramsey]

I think I would camera all of the lines now. Don't wait until the restoration is complete. The gurgling doesn't sound good. I doubt that it's venting, but it could be water left over in the drain lines, and if so, why? If concrete needs to be broken, it's better when the units are vacant.

The odd thing is the main sewer is clear now. Only one unit #19 has this gurgling sound. Yesterday they had a plumber rotoroot or snake out their toilet line upstairs to down and into the sewer. The toilets stopped making noise initially, but the sound recurred this morning. There is no issue in any other unit at all at this point. Only this one unit. This unit had the most damage b/c they had laminate floor which trapped the water between the slab (which is hardened from age and whatever hardener they used in the concrete in 1971) which doesn't absorb water, the water proof padding and the laminate floor so it was removed en masse ~500 square feet of it. The unit owners' insurance is paying for the restoration which is scheduled for tomorrow. So obviously they are a bit gun shy. I do not think they have a clog anymore if they ever did in the toilet line. (The DID have a clog at their laundry+kitchen sink line which was cleared and has not had a problem since. ) They have no problems flushing, washing or running faucets; just the movement of water in the downstairs toilet when upstairs flushes. And when downstairs flushes it gurgles. They said this sound began around the same time that the main sewer became clogged. Is that perhaps just a coincidence? They were told they cannot jet clean just the local plumbing since the back pressure would risk flooding the unit. Is it even worth camera checking only this one unit? I have a 10M inspection cam I mounted on a snake. Could put that partly into the downstairs toilet and see what it sees I guess. The plumber they used is same company that jet washed our HOA sewer line and camera checked it. It cost $350 for the cam plus recording. Is that camera superior to using something non-commercial for spot check like this?