Venting Question Bath Sink

[Mswlogo]

We just had a new house built.

It has a Septic with a pump up to a leech field. (Maybe 10ft rise). It is supposedly back vented (not sure what that means) but if the vent on the house was high enough we didn’t need a crazy high vent at the end of the leech field. And it was high enough. I think it vents backwards through the drain. Not sure any of that matters just letting you know.

Well the plumber wasn’t the best. Forgot plumbers putting on 2nd tub drain. And plumbed hot and cold backwards on the same tub. He was not keen on coming back as each cabinet came in and wanted to wait until everything was in and come once. Well I wasn’t gonna wait 6 months (and that was the spread on cabinets arriving). So I finished things myself As they arrived.

He mentioned which sinks need vents. Up stairs guest bath and kitchen sink. All seem fine.

I didn’t think this dual sink in master bath needed any under sink vents. But the sink on the left had a tiny bit of smell. Toilet is to the left of the left sink.

House is tricky because its post and beam and SIP (solid foam) for exterior walls. So he avoided most plumbing in any exterior walls.

I thought maybe the left sink plumbs over to the other sink on the right in the wall and might need a vent. I thought for sure at least one must be vented in the wall.

So I added the vent to the left sink and it’s much better but still get a whiff when I run the water. If I plug the drain, and run water, no smell. Sink on right never smells.

Could the possible need for a vent on the right sink cause the left one to stink? Could it be a bad vent?

This is the left sink. The right sink looks identical but no vent.

 

[Reach4]

Did you use clear primer on your glued PVC? Did you glue the joints?

I would prefer slip joint traps.

You could try filling the bowl with water. Add 2 tablespoons of liquid chlorine bleach. Stir. Then add 2 tablespoons of vinegar. Stir. Let the faucet slowly dribble water into the bowl so the bleach moves thru the overflow. I am not a pro.

In retrospect, it would have been nice to have photos of the roughed-in plumbing.

 

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[Jeff H Young]

Due to the sketchy sounding plumbing with bass akward venting you told us about about. the following may or may not work.
Add another aav on other sink . EVERY sink needs a vent or an AAV an AAV is not equal to a vent but in a proper plumbing system they do fine . (info provided suggests defects in septic system which might be a problem)

I think on brand new sinks there is no stink in the overflow its coming from the dwv system due to bad or incomplete plumbing work

 

[Mswlogo]

Did you use clear primer on your glued PVC? Did you glue the joints?

I would prefer slip joint traps.

You could try filling the bowl with water. Add 2 tablespoons of liquid chlorine bleach. Stir. Then add 2 tablespoons of vinegar. Stir. Let the faucet slowly dribble water into the bowl so the bleach moves thru the overflow. I am not a pro.

In retrospect, it would have been nice to have photos of the roughed-in plumbing.

It’s all new house. Doubt anything is built up.
Nothing smells unless I run water. It’s gas on the other side of the trap.

Chlorine is a no-no with Septic.

Yes, I primed it, it’s all tight. I mark each joint to, make sure it’s fully seated.

 

[Mswlogo]

Due to the sketchy sounding plumbing with bass akward venting you told us about about. the following may or may not work.
Add another aav on other sink . EVERY sink needs a vent or an AAV an AAV is not equal to a vent but in a proper plumbing system they do fine . (info provided suggests defects in septic system which might be a problem)

I think on brand new sinks there is no stink in the overflow its coming from the dwv system due to bad or incomplete plumbing work

Plumbers work seemed ok in general. Just stupid mistakes and not very flexible.

Plumber didn’t install septic. Septic designer and excavator did. It all seems to be fine and was inspected.

Just making you aware of the back venting thing in case it was a factor. The vent pipe on the house had to be some number of feet above the leech field. If it is you don’t need a tall vent pipe at the leech field.

I’ll try adding a vent to the other sink.

The smell is super minor. Sometimes don’t even notice it. Does it for maybe 10-15 seconds if the sink hasn’t been used for like 12 hrs. No other sink has an issue.

 

[Jeff H Young]

ok well in any case all sinks need vents it could be the problem . no reason not to have one thats just wrong .

 

[Mswlogo]

ok well in any case all sinks need vents it could be the problem . no reason not to have one thats just wrong .

There might be one right behind the wall. It’s in an area that there is no reason to not vent up in the wall. I don’t know with these sinks if he planned on under sink vents or fully vent one or the other or both in the wall.

So on the other places he said needed a “local” under sink vent it made sense because there wasn’t an easy path up. Again mostly due to Post & Beam and the SIPs. Kitchen is against a SIP exterior wall. There is no path up. Up stairs bath, sink on interior wall, under a shed dormer roof. Not worth punch hole in roof for 1 small sink. Rest of bath is on a wall of the shed dormer and he vented out there.

There are no holes in the roof. Which is real nice. All vents go out the side walls of the shed dormer. This gives us a lot of freedom on solar panels and looks.

Note there is also attic in this house. Its’s called a cold roof. 2” tongue and groove, then 12” SIP, then strapping (that is the “attic vent”), then sheathing, then shingles.

But these sinks are on first floor on an interior wall and I know the toilet is vented. And it has a closet above and there are vent pipes in that closet. So it was probably the easiest area to do normal full venting. And I assumed it did and initially didn’t put any under the sinks.

Washroom is fully vented, 1/2 bath fully vented, most of up stairs full path is vented.

Only kitchen sink, 1 sink upstairs needed these under sink vents.

I thought these two sinks should have been ok.

I might have rough photos. Mad I’m not sure if I do.

The bath of concern is the corner on the right closest to garage on the 1sr floor.

And the interior wall the sinks are on is roughly inline with the right dormer wall.

 

[Tuttles Revenge]

Well the plumber wasn’t the best. Forgot plumbers putting on 2nd tub drain. And plumbed hot and cold backwards on the same tub. He was not keen on coming back as each cabinet came in and wanted to wait until everything was in and come once. Well I wasn’t gonna wait 6 months (and that was the spread on cabinets arriving). So I finished things myself As they arrived.

Putty shouldn't be forgotten.. but it also shouldn't leak if they do, just won't hold water. The seal is the rubber gasket under the tub.

No chance would I come back to set each sink as they arrived. At least not unless I was getting paid by the hour. We give bids for most of our work and its based on showing up and doing all the work at once. There are exceptions of course if one sink doesn't show up on time.. but making a bunch of individual trips for an hours worth of time each isn't profitable unless you're charging service rates or getting paid for travel time. And a lot of small single operator shops aren't set up for that type of work.


You shouldn't get any sewer smell inside your home even if you had No Vents at all. The sewer gases are blocked by the water trap seal at each fixture. The vent is there to prevent siphoning of traps. Often times toilets wax gaskets are the source of sewer gas smells inside of bathrooms. But if you're able to smell it with the sink running that seems really odd.. like it shouldn't ever happen.. ever. There has to be a reason other than venting that is causing the smell. Like the sinks themselves and specifically the overflow which can build up gunk and stink. I would first see if the sinks have overflows (most do), verify that the pop up assemblies are made for overflows, check and see if the smell is coming from that point and or clean that using dilute bleach (bucket under the pop up to avoid dilute bleach from reaching your septic.

 

[Mswlogo]

Putty shouldn't be forgotten.. but it also shouldn't leak if they do, just won't hold water. The seal is the rubber gasket under the tub.

No chance would I come back to set each sink as they arrived. At least not unless I was getting paid by the hour. We give bids for most of our work and its based on showing up and doing all the work at once. There are exceptions of course if one sink doesn't show up on time.. but making a bunch of individual trips for an hours worth of time each isn't profitable unless you're charging service rates or getting paid for travel time. And a lot of small single operator shops aren't set up for that type of work.


You shouldn't get any sewer smell inside your home even if you had No Vents at all. The sewer gases are blocked by the water trap seal at each fixture. The vent is there to prevent siphoning of traps. Often times toilets wax gaskets are the source of sewer gas smells inside of bathrooms. But if you're able to smell it with the sink running that seems really odd.. like it shouldn't ever happen.. ever. There has to be a reason other than venting that is causing the smell. Like the sinks themselves and specifically the overflow which can build up gunk and stink. I would first see if the sinks have overflows (most do), verify that the pop up assemblies are made for overflows, check and see if the smell is coming from that point and or clean that using dilute bleach (bucket under the pop up to avoid dilute bleach from reaching your septic.

They are brand new sinks. If it was in overflow it would stink all the time.

I didn’t know that’s what vents do, that’s good to know. I doubt vent on other sink would change any thing then. Because if trap was siphoned off it would stink without running water.

I think it’s gas on the other side of the trap. Running water stirs it up enough that bubbles make it through. That’s just my hunch.

It was not a bid job.

Maybe I need a see through trap to see what’s going on.

 

[Mswlogo]

Ahh, I did find a pic.

It should be fine, right?

 

[Reach4]

Chlorine is a no-no with Septic.

Not as bad as you might think. If it were not septic, I would have suggested 1/4 to 1/2 cup of bleach.

Is Bleach Safe for Septic Tanks and Septic Systems? | Clorox®

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It is good that you have that photo. Yes, your left and right sink should be nicely venting.

 

[Jeff H Young]

So we cant blame it on old scummed up sink overflow or a vent. something else going on.
Ive had to go back on custom homes for many reasons but yea I try to minimize it.
Are you sure the smell is coming up the trap not a crack in a pipe or something ? It would be improper to rely on but the aav you added on one side would probebly help the other sink , Im assuming the 2 inch goes someplace and wasnt just capped off in wall or above the plates .

 

[Mswlogo]

So we cant blame it on old scummed up sink overflow or a vent. something else going on.
Ive had to go back on custom homes for many reasons but yea I try to minimize it.
Are you sure the smell is coming up the trap not a crack in a pipe or something ? It would be improper to rely on but the aav you added on one side would probebly help the other sink , Im assuming the 2 inch goes someplace and wasnt just capped off in wall or above the plates .

If a crack. Why only if I run water. Worried it was the water itself at first. But if I plug the sink. No smell. Open the plug. Get smell for a few seconds.

And why this one sink.

It is probably the closest sink to the pipe going out to septic tank. Below in the cellar.
Cellar it open. Maybe I’ll post a couple photos. In case anyone sees anything.

 

[Jeff H Young]

the p trap is a water seal once one seal breaks there is no reason for the other to break . nothing is identical in this world so something ever so slightly differant about the one sink plumbing than the other maybe a burr or pooling of excess glue in the bottom makes the one sinks trap seal break. I can tell you I totally doubt anyone can tell you with certainty why one side and not the other. you could experiment with deeper trap seals . An easy attempt might be to add an aav on other sink , maybe temporailly remove one elsewhere so you dont have added cost and screw a plug in place if you wind up not using it permanately at that location.
You could have drainage issues where pipes are backing up. a lot of possibiltys but adding the aav might take care of it though I hate not knowing what the real problem is. and taking a wild guess .
I dont know what happened or what other people do but I dont walk away from a job like this Im assuming the plumber built this and didnt just do a tiny part so I totally disagree with anyone saying they would refuse to come back or at least discuss the problem , maybe you really pissed him off I dont know thats nothing i care to know details but just saying what I think is right to do

 

[Mswlogo]

Few things.

First, he didn’t “walk”
When the 2nd floor bathtub flooded the first floor, I sent a text at 11pm with a photo of the mess.

His response wasn’t, I’m sorry, I’ll be there 1st thing in the morning to fix. He bitched that the ding on his phone woke his baby. Because he doesn’t know how to use do not disturb on his phone. And if he doesn’t know how to use his phone put it out of ear shot of his baby if that is his priority. Don’t blame me. And if he did his job he would not have got any text.

Like you said, it should not have happened.

After his last visit he more or less said I’ll be back when EVERYTHING is in. Kitchen was in the next week but bathrooms were not due for months and when they did arrive they were wrong and ended up getting reordered.

So I’m supposed to have no kitchen because he doesn’t want to make an extra trip? Which I never said I wouldn’t pay for.

Somewhere along the way I learned he plumbed hot and cold backwards on the same tub. He also mounted the shower head about foot to high.

So I simply never called him back and finished everything as they came in.

I do better work than he did.

 

[Jeff H Young]

sorry about the issues I didnt think it was just too many trips .
Anyway beyond my comments in my other post I dont have any other tips for now

 

[Mswlogo]

Here are a few more photos

First photo is what the center pipe going down goes to.
So how is the Toilet getting vented? I think the only vent on this whole side is that 2" pipe going up to the closet
Seems like a lot of ups and downs for the Toilet? Sinks are probably ok.

This is directly under those sinks, top right is where that center pipe comes down
Top left is shower from other side of bath. There is a trap in the cellar under the shower.
Does shower vent through all this too?

This is following the line down, you can see toilet coming down in top of photo slightly to the right of center, next to sink drain

This is above those sinks

This is continuing that vent

And this goes out the side of the Dormer

 

[Jeff H Young]

Looks good to me! toilet wet vented from lavs and shower can use the vent as well

 

[Tuttles Revenge]

All the DWV in the photos looks like a competent person installed them. However... the main reason colored primer and glue is used is to easily visually see that all the joints are made up properly. Did the DWV get a pressure test with water? Can it be verified that all of these joints are glued together? What caused the flood from one bath to the other?

Just because a sink is brand new doesn't mean something can't stink in its overflow. It can't hurt to perform a test to eliminate it as a possibility. Its more likely that than air bubbling backwards up the trap when water is flowing downstream. We install thousands of traps on sinks each year and never have anyone complain about smells coming up from them. But we do get that issue from overflows on this site from time to time...

 

[Jeff H Young]

I agree with tuttles , Ive never had a single sink have that stink on a new install . I think its a plumbing issue. could be a nail,screw hole crack , a sawsall , a partially cut pipe bad glue joint. many things or the first in 10s of thousands . work looks fairly clean Id say very clean we cant see primer it sets up a flag but it might be easily determined it was or wasent primed. I work so little with pvc for dwv in fact Ive never been on a job that was entirely pvc but have done pvc underground and cast iron above round.
Of cource Id never go without primer but if this wasent primed ? then what ? rip out the entire system I think not .
So rather than pick it apart not even knowing that it wasent primed Id concentrate on the problem but as a posibly unrelated issue look into properly glued and primed