DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Plumbing (
-   -   Adding A Bathroom (

Calm_Blue_Ocean 02-09-2008 06:22 PM

Adding A Bathroom

I'm adding a bathroom in an unfinished basement. Sorry for starting a new thread on this, but the situation has changed and I didn't want this to get lost. There's only one place I can put the bathroom and have a basement layout that works. I jackhammered the floor and was a little surprised by what I found:

The line on the left (with the slanted cleanout) is the main sewer drain leaving the house. I'd like to have a second line joining this to the right - this will drain a toilet, sink, and shower. What I want to know is if I can remove the second clean out and p-trap, tie into the main line through this existing connection (which is in the perfect location) and then rebuild the cleanout and trap and connect it to my new drain line.

To be honest, I'm not sure how the existing set-up works. As you can see, there is a flex tube allowing for drainage under the slab. This flex tube connects to a drain which leaves the house. This drain also connects in a loop back to the sewer through a p-trap. At the bottom of the second cleanout is a valve which only allows flow towards the sewer (from the p-trap). The p-trap does contain water. I live in a area which is not prone to flooding (I'm at the top of a large hill), although the foundation does sit on heavy clay. Am I correct to assume the second connection is to the storm sewer?

I don't quite understand how this system functions (although I assume it handles backflow). I'd be greatly appreciative if someone could explain it and advise me as to wether or not I can move it. I'd like to flip it around, run it parrallel to my new line for a short distance and then connect into the new line just upstream of where the new toilet will connect if possible.


Marlin 02-09-2008 08:29 PM

I've yet to see any setup like that.

Ron The Plumber 02-09-2008 09:35 PM

What a mess.

Calm_Blue_Ocean 02-10-2008 01:10 AM

OK, so it's not just me. The flex tube is in direct contact with the slab and is on top of over a foot of dry sand. I can't imagine it ever carrying water. The p-trap and cleanout also seem rather pointless.

Marlin 02-10-2008 05:50 AM

That's a U bend, not a P trap.
Where does that flex line go? It looks like a vent due to the orientation of the line. Where does the line go upstream of the wye, floor drain?
Their won't be any new problems moving that setup over to get another wye in but that isn't going to solve the mess that you have now.

Calm_Blue_Ocean 02-10-2008 12:49 PM

Functionally, how does a U bend differ from a P trap? It seems to me they are doing the same thing.There is water at the bottom of that bend. The flex pipe continues under the slab towards the middle of the foundation; beyond that I have no idea. It has nothing to do with the floor drain. The pipe with the temporary orange cap on it in this photo is the floor drain (I plan to get rid of this by capping it beneath the slab).

The flex tube was not securely fastened to the wye; I disconnected it rather easily. Any water that did flow through the flex tube would have drained out under the wye. The house is 30 years old and there are no signs of water.

What would the flex tube be venting? It has holes along the top which made me suspect it was to collect drainage. As I memtioned before there's a one-way valve (flapper) at the top of the U bend under the cleanout .My amateur interpretation of this set-up is that the flex tube drains into the storm sewer or a tile bed and the second trap prevents gas and water from backing up into the house (by dumping it in the sewer). If this is the case, the system is not working and not needed. The city I live in grew up around a large river valley. This was one of the first neighborhoods to be built outside of the valley (far above the water table); perhaps under the slab drainage was code for the city at the time.

What do you think needs to be done to "solve the mess" Marlin. Thanks

jpplumber 02-10-2008 02:18 PM

As I recall you were trying to install another living unit to rent out due to very rapid growth in an area that had no cares about inspections....nobody could have envisioned what you have there. A running trap that has no water flowing through it (or the fitting on the right with the flex pipe is installed backwards) and what looks like a foundation drain tied into the sewer pipe. You really need to find out where the pipes are coming from and where they are going. I wouldn't proceed any further until I got a sewer camera out there and trace everything out (unless water is flowing through the trap and going to the left). If the flexible pipe is actually functional you will most likely need a pit with a sump pump instead of attaching it to the sewer system. Did someone say what a mess? Ditto.

Ron The Plumber 02-10-2008 02:19 PM

You need to have the lines camera-ed, to me it looks like you have two lines that's drain in one direction, then there is a cross over on the drains, weird, the trap is not even needed, you need to get rid of the trap and find out how and where these line go to., You might have a storm drain tied into your waste line which is not good, and not allowed.

You have a mess to figure out.

Calm_Blue_Ocean 02-10-2008 05:11 PM

The line on the left with the slanted cleanout is undoubtedly the sewer and there is only one sewer line leaving the building (I have flushed toilets and run taps and peaked through the cleanout to be sure). The other line has a very noticable slope - it runs away from the house. I suspect this second line goes into the storm sewer – is this the one you suggest I have camera-ed? I can’t imagine this line ever being used, however there is water in the trap and this suggests to me it has backed up – I assume the trap would have dried out otherwise. If the flex tube does nothing than this system (which I'm assuming provides protection from the storm drain backing up) is also pointless (and as Ron said, probably not legal). You’re absolutely correct about shotty workmanship in this town JP. I spent the last two weeks helping a friend clear an ice dam from his roof and redo some bathroom vents (they had been vented directly into the attic – the ‘professional’ he hired was too lazy to connect them to the roof vents). I do however; intend to do things right. I’m a prof. at a local college; I’ll run this by our plumbing instructor and see what he has to say.

Marlin 02-10-2008 10:22 PM

Functionally a U bend and a P trap do the same thing.

Which way does the back flow valve work? It allows water into the main sewer line right?
Here is what I'm thinking.
You have that flex line which is a foundation drain or something of the sort which deals with rain/groundwater. Instead of just running the drain line right to the dry well or whatever you have they used a wye and tied one end into your main sewer line. In the case that your dry well fails or is full the excess will run into the sewer line and your basement won't flood. If that's the case not only is it probably illegal, they made a lousy job of hooking it up.

Calm_Blue_Ocean 02-10-2008 11:25 PM

Yes, that's correct Marlin, those are my thoughts as well (as I stated). I think the flex tube drains the weeping tiles around the foundation. I suspect it drains into a storm sewer or tile bed (actually a tile bed or 'dry well' would make more sense as the storm sewer would be unlikely to back up where I'm located).

Now of course the question remains...what to do about this? I plan to remove the trap and tie the drain line from my new washroom into the sewer connection where the trap currently connects. My line pretty much has to go in at this location. I can fix the flex pipe connection (i.e. so that it sits inside the ABS instead of around it), but I'll have to seek some advice as to how to deal with a potential backflow problem. I'm wondering if I can remove the trap and cap where it connects to the wye and then put a back flow valve of some sort where the flex tube connects and exits the foundation.

BleachCola 02-11-2008 03:15 AM

do you have any more pics?

Calm_Blue_Ocean 02-11-2008 06:14 PM

Hey Bleach, There's not much more to see... what would you like photos of?

I've done some research and learned a few things. The pipe drains the foundation's weeping tile and the backflow valve allows excess water to discharge into the sewer during the spring melt as I suspected. The surprizing thing is that this is in fact legal in this city and the norm for houses this age. This may change in the near future however, as indicated by this recent statement by the municipal council:

The issue of rainwater going into the sewage system is one that was fairly standard in many communities several years ago, but this now contributes to the capacity issue and the roof leaders should be disconnected. The Municipality will be bringing forward a new Sanitary Sewer Bylaw which would give Administration authority to direct weeping tile connections to be terminated and switched to surface drainage with sump pits, as needed.

The worst case scenario, in the event that the amendment is not approved, is that a major storm event would occur, causing the sewer system to surcharge and overflow, thereby creating a non-compliance issue with environment, flooding of basements and surcharging in buildings.

The city is a little behind the times and it has caught up with them now that the sewage treatment plant is at full capacity. It will be another year until our new plant is completed. I suppose the thing to do is to reconnect the flex tube properly (not that it's doing anything) and perhaps redirect the backflow to a sump pump.

jpplumber 02-11-2008 07:17 PM


direct weeping tile connections to be terminated and switched to surface drainage with sump pits, as needed.
I think this is your answer for what to do about the flex pipe, you will just be ahead of everybody else, but you need to find a place to pump the water too. Then you can get rid of that trap and back flow valve (from what you said I picture the back flow valve is in the tee connected to the trap, is that right?) Then you can tie your new plumbing into the existing tee of the sewer line

Calm_Blue_Ocean 02-11-2008 09:47 PM

Yes JP, that's where the valve is. My plan is to remove the trap and use it's connection to the sewer for my new branch line (which means I don't have to splice into the main line, which I'm actually rather happy about). I'll reconnect the flex tube to the wye (properly), and run the other connection of the wye (which brings the back flow from the weeping tile) to a sump pump. My new sewer line will end with a cleanout under a small coat closet just outside the bathroom. I suppose I can put the sump pump here too (everything will be hidden under a trap door at the bottom of the closet).

Where to pump the water to is indeed the next question.

All times are GMT -5. The time now is 01:19 PM.

Copyright 2003-2014 Escalate Media LP. All Rights Reserved