Basement bathroom rough-in, vent, ejector pump questions

[Ryanwj]

I have a 2 yr old house that had an unfinished basement when we bought it. The basement has been plumbed (to some extent) for a bathroom underneath the slab. What I have is three stubs coming out of the slab, a 2" stub where a vanity sink would go, a 4" stub where a toilet would go and a 1-1/2" stub where a tub/shower would go. About 10' away I have a pit for a sewage ejector pump. Based on extensively searching through many posts on these forums I have managed to put together what I think is the correct way to finish the DWV piping for this setup using a group vent that tees off where the vanity sink will connect to the 2" stub. My plan is to tie that vent back into the vent for the ejector pit in the basement ceiling and then run a vertical vent up through a chase into the attic and out the roof eventually. I don't believe my house has a main vent stack as it appears there are 3 separate vents through the roof. One vent is located near the kitchen/laundry, and one each near the two existing bathrooms on the main floor. I assume this means I will have to run a new vent through the roof for the basement bath. I'd like confirmation of this.

Assuming the above is correct (I will be posting a pic below that should help anyone interested on confirm), my big question is whether I can run an additional drain from a proposed wet bar into the basement vanity drain line above the slab. I'm obviously trying to avoid busting the slab to tie in this wet bar, but I'm worried bringing it in above the slab might mess up the group vent. I assume if this was "legal" I would need to tie it in below the waste/vent tee for the vanity sink. The wet bar sink would be vented locally and said vent tied into the group vent for the bathroom that eventually will protrude through the roof. Please see the attached sketch for clarity. Any thoughts or helps is appreciated as this is my first venture into significant DWV plumbing and I'm trying to do it right. I have not found any books that address a situation close to the one I have described.

 

[Dunbar Plumbing]

In Kentucky you have to vent that sewage ejector individually to the roof; no exceptions.

Also in your piping configuration you are lacking a vent for the shower and the toilet; the pipe serving the vanity can be vented off the top of the tee.

So in Kentucky you'd be tearing out all of that plumbing under the concrete and reworking the piping system to acquire the proper venting.

One of the main reasons a sewage ejector vent cannot be tied into the rest of the plumbing system is the possibility of clogs either coming back through the vent of the sewage ejector or the sewage ejector failing and pumping sewage through the vents. Highly unlikely but with plumbing.......anything can happen.


A great deal of air movement is created with the operation of a sewage ejector. It can cause a disruption of trap seals depending on how forceful the pump acts.

 

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[George R]

I'm no pro but I do have a few questions for you that will help the pros chime in.

First a comment, the 2" line is probably for a shower, the 1.5 " line is probably for the sink.

Is the 2" line embedded in concrete or is there a "gravel hole" that can be used for the shower P-trap? Is there a p-trap in the floor?

Why not contact the builder (or the builders plumber) and have him tell you what is there? Are you certain that there is no vent that goes thru the roof?

 

[Ryanwj]

You had some of the same questions I had. Both the 1-1/2" stub and the 2" stub are embedded in concrete - no gravel or anything like that to speak of...as far as the P-trap, it appears (although I have no way of being really really sure) that the 2" line is not trapped. I have not checked the 1-1/2" line b/c it's capped right now, but I am assuming if the 2" is not trapped the 1-1/2" is trapped. If neither is trapped then obviously I have no choice but to tear up the slab. I believe the layout is a typical 5x8 setup with the tub/shower at the far end...that end is bordered by the concrete foundation walls on 2 sides and the dimensions of the stubs relative to walls seem to indicate the fixture layout I showed in the sketch.

Somewhere on these forums I've seen discussion of the IPC allowing a wet vent setup for a bathroom group that would allow the whole group to wet vent back to the vanity tee and then vent the vanity as usual. I am operating under the assumption that is what my plumber had in mind.

I did not realize I can not tie the ejector vent to the other vents - that means I may have to penetrate the roof twice. As far as I can tell there is no evidence at all of any vent for the ejector or any of the basement bath fixtures. The ejector pit is located underneath a stairway so the easy directly vertical route for a vent pipe is not feasible. Luckily I have a chase about 5' horizontally from the pit that I can use to route to the attic.

Finally, in terms of the plumber, I have already had several dealings with the original plumber of the house and none have gone very well. I am working on getting them in here to explain my options, but I am looking to you folks for more informed advice. I don't know if its just my luck, but sometimes when I call in the "experts" I quickly realize how some of them only have expertise in cutting corners without getting caught.

 

[hj]

In Kentucky you have to vent that sewage ejector individually to the roof; no exceptions.

Also in your piping configuration you are lacking a vent for the shower and the toilet; the pipe serving the vanity can be vented off the top of the tee.

He is guessing at the piping arrangement, but it is probably actually installed with proper venting.

So in Kentucky you'd be tearing out all of that plumbing under the concrete and reworking the piping system to acquire the proper venting.

Extreme solution unless it is really poorly installed, which is not likely in a new house done by a licensed contractor.

One of the main reasons a sewage ejector vent cannot be tied into the rest of the plumbing system is the possibility of clogs either coming back through the vent of the sewage ejector or the sewage ejector failing and pumping sewage through the vents. Highly unlikely but with plumbing.......anything can happen.

ABSOLUTELY cannot happen. There is no connection between the pump discharge and the sump vent, or any other vent for that matter. The reason a separate vent is sometimes required is that if the cover of the sump is not sealed properly, and the vent is tied to the house sewer system, sewer gases can circulate into the sump and from there get into the building.

A great deal of air movement is created with the operation of a sewage ejector. It can cause a disruption of trap seals depending on how forceful the pump acts

It can aspirate trap seals if it pumps past the branch connection and there is no individual vent, but otherwise, it also will not happen.

 

[Jadnashua]

There is usually no reason to make the vanity sink 2" (doesn't hurt, but not needed), while a tub can be 1.5", if it is a walk-in shower, it must be 2" to pass code.

 

[Prashster]

I live in NJ and my configuration is almost like yours: I looped the fixture vents back to the sewage vent and ran one pipe through the attic. I also discharged my sink line above ground into the toilet's vent (which is downstream in my config) which created a 1ft wet vent section. It all passed. My inspector only required adequate pipe diameters for this.

Also, Rugged, for my clarification: the pump is screwed into the discharge. It can't ever shoot into the vent. If it stops working, then the basin will back up through the shower and toilet before it climbs the vent. I thought that was the purpose of rising all vents above the flood lines of the fixtures. What am I missing here?

 

[Ryanwj]

prashter, I don't understand your comment on discharging the sink into the toilet vent. My config doesn't have an individual vent for the toilet or the tub/shower only the group vent at the vanity.

jadnashua, I knew 2" seemed big for the vanity line, but I thought perhaps using the IPC wet vent setup with one vent for the group might require the 2" stub (I didn't install the 3 existing stubs as they were there when I purchased the house - if I have to go into the slab I'll probably redo everything and individually vent each fixture)

hj, I am assuming the pipes under the slab were sized properly for a wet vent group setup as I've shown - my understanding is that this would require only a vent from the vanity up to the roof (hopefully tying back into the ejector pit vent before running to the attic)

 

[Prashster]

I see that you don't have a vent for the toilet. I see that in a LOT of posts of builder-provided rough ins on this forum. I'm not sure why.

Never mind about my draining into the toilet vent. I thought you'd be draining the bar sink into the lav vent, but I see you can do this below the takeoff, making it a non-issue.

In my town, the big no-no would be having that single group vent off the lav tee. If that was allowed, you'd at least need extra wide pipes on the lav drain to handle the air flow from a shower and toilet being on simultaneously.

 

[Dunbar Plumbing]

The question on 2" coming through the concrete I believe that any pipe brought up through the concrete must be 2" if it serves as a drain....1.5" if a vent.

As far as the rest of that system.....I guess it is code to have that piping arrangement in your area. A plumbing inspector in my area would have you jackhammering that piping system out and turning up a vent for the toilet and shower as a requirement.

I just cannot figure out how someone is going to flush the toilet and not have the shower trap get siphoned. GOOD LUCK

 

[Prashster]

I just cannot figure out how someone is going to flush the toilet and not have the shower trap get siphoned. GOOD LUCK

Easy: just turn on the shower for 10 seconds after every time you flush!

 

[Ryanwj]

So if I am understanding this correctly, there is not an issue with the wet bar drain and vent strategy that I've proposed. Will the wet bar sink add too much load to the waste/drain for the ejector pump setup?

I do see what you mean RUGGED about siphoning the tub/shower trap. I don't understand why the heck the rough in plumber could not have just provided vent stubs for each fixture inline with the wetwall which would greatly simplify this whole mess.

Anyway, I'm attaching the sketch from the IPC manual I referenced on wet venting and group venting. I am assuming this is what the original plumber intended. This sketch is consistent with RUGGED's concern about the toilet drain "passing over" the tub drain. It shows that the toilet drain does not pass over anything else in the group.

 

[Ryanwj]

I removed the caps on the pipes and poured water into the stubs tonight to confirm that the 1-1/2" stub has a P-trap and the 2" stub does not. Thus, the 1-1/2" must be for the tub/shower as I assumed and the 2" for the vanity.

I'm still concerned about the toilet wet venting past the tub/shower and siphoning the trap.

 

[Dunbar Plumbing]

In my experiences of the years I've been in this trade, KY/OH/IND had wet venting as code at one time but KY does not now.

Now from all the times I either drain clean or reworked some of these combination waste/vent systems........it was always common to see vents either obstructed partially or fully. In Cincinnati in the older plumbing they like this way of plumbing and some call it "airplane plumbing" which I really don't know what that means other than it goes in fast and done by fly-by's.

But in the new construction of plumbing in Cincinnati the plumbing codes are somewhat similar to KY. But if you head to Clermont county........no isolation valves for the toilet/sinks/dishwasher???????????? WTF? That makes absolutely no sense whatsoever.


But in your area which we do not know.....your codes are dictated by what is enforced.

That one diagram on the wet vent is what I see in some of the older homes until the codes changed.

Branching off that toilet arm picking up the tub and vanity might work in the beginning but both of those fixtures are notorious for clogging over time........robbing the path of flow for either wastewater OR air which conditions the venting for both fixtures.

Like a clogged artery slowly getting worse until someone clears the drain. And how effective is a drain cleaning? You never see the final result......just the fact it's flowing. A repeating cycle that never ends on the spectrum of whether the system functions without error.

Lots of errors with that system in my opinion but saving $10 in pipe and fittings isn't what I'm about.

 

[Ryanwj]

local plumber response

I had a local plumber come out and look at my setup today. He agreed with my basic plan of the wet group vent for the bathroom coming off of the 2" lav stub. He says this is a normal basement rough-in for this area and we'll have no trouble with inspector.

However, he was unsure of the "legality" of draining the wet bar sink into the lav drain pipe - even it it was tied in below the waste/vent tee. He was not sure the pipes are of sufficient size to allow for the extra load (although he admitted a bar sink is very little load) in the drain system. I suggested the revent setup I showed in my initial diagram and he said that would work well but he still wasn't sure if it would pass code.

Does anyone know of a reference as to what code may or may not require in terms of pipe sizes for a wet/group vent like the one I've shown?

RUGGED - I sympathize with your complaints about this setup, but I don't plan to live in this house forever and I don't see the point in going through the trouble of busting the concrete and redoing an install that passes local code for a basement bath that will get very little use - it primarily serves to increase the value of the house. If I had built the house I would have done this and quite a few other things differently. Hopefully one day I'll get to build a house but until then...this is what I am dealing with.

 

[Dunbar Plumbing]

Aye it's no problem here on my end. I just was pointing out what I found was obviously a red flag. The trained eye that picks up on what we see and do every day.

I guess when I recite code I am implying more than just the schematics. I'm implying that when things aren't done up to code or something is installed incorrectly, this leads to problems with the answers clear to see.

Will you have problems instantly? Certainly not. If you don't plan on using it much and you keep an eye on the shower trap whenever you flush the toilet, it should be fine. I try to be optimistic as much as possible but sometimes I'm sure I'm being pestimistic...........this happens a great deal since my profession is geared towards diagnosing and repairing errors.

I hope you appreciate the heads up I gave you......which I'm sure it helps to know the in's and outs of any project anyone takes on before they start.