Venting a basement bathroom/laundry room

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Craig Alwine

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Hello! I need some plumbing help with my basement bathroom/laundry room. My house was built with the washer draining into a sump pit with a sump pump via a 4" main line. A toilet and sink are also plumbed to the main line, but have never been installed or operational. Now that I'm ready to finish this room I want to add a shower also. There are no individual vents for the sink, toilet, or washer. You can see on my drawing how I want to add the shower to the main line via a wye connection. The sewage pit is vented with 1 1/2" pipe and is connected to the whole house vent pipes. I'll replace the sump pump with a 1/2 HP sewage pump and replace the 1 1/2 " discharge pipe with a 2" discharge pipe that connects to the main line going into the septic tank. How do I properly vent this setup? Will an AAV at the sink be enough? I'm in Indiana and am told Indiana goes by the Indiana Plumbing Code and has adopted UPC.

Edit: the drawing does not show it, but the washer is connected to the main line that drains into the sump pit.

Screenshot 2021-11-01 202128.png
 
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Reach4

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The sewage pit is vented with 1 1/2" pipe and is connected to the whole house vent pipes.
IPC 906.5.1 will tell you if 1.5 inch vent for the septic pit is enough.

For the lavatory, you can use an AAV. That can vent the shower and toilet. You could connect the lavatory to the line out of the shower at least 4 inches after the trap. Use wyes or long sweeps.
 

Craig Alwine

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IPC 906.5.1 will tell you if 1.5 inch vent for the septic pit is enough.

For the lavatory, you can use an AAV. That can vent the shower and toilet. You could connect the lavatory to the line out of the shower at least 4 inches after the trap. Use wyes or long sweeps.
Thanks Reach 4. The lavatory is already connected somewhere to the main line. I'm not exactly sure where, as it was plumbed when the house was built and it's buried in concrete. Does it matter where the lavatory ties into the main line? I'm assuming it runs perpendicular to the main line which would put it's connection point between the shower and the washer, about 16" above the washer. Does the washer need vented? I've been using it as is for 17 years and never seemed to have a problem. The sewage pit vent ties into the vent line that connects to the upstairs plumbing and out through the roof. Is this acceptable? I've read where sewage pits need to have their own dedicated vent. Again, it's been hooked up like this for 17 years and never noticed a problem, but I've only ever had the washer drain into it until now.
 

Reach4

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The lavatory is already connected somewhere to the main line. I'm not exactly sure where, as it was plumbed when the house was built and it's buried in concrete. Does it matter where the lavatory ties into the main line?
It does if you want the lavatory to supply a wet vent for the shower and toilet. Otherwise, the shower gets a dry vent before joining the toilet waste. Out of the trap stays horizontal until the vent. Vent for shower could be an AAV and the riser stays within 45 degrees of plumb until the AAV, which will be at least 4 inches higher than the flood level of the shower. AAV is mounted within 15 degrees of plumb.
 

Craig Alwine

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Thanks again Reach4. Sounds like the AAV at the sink will be the easiest remedy for me as connecting a dry vent at the shower may be too tricky in my situation. Could you take a look at my drawing below to make sure I am understanding you correctly?

One more question. The sewage pit vent is connected to the vent line that connects to all other vents throughout the rest of the house, then out the roof. I've read a sewage pit should have it's own dedicated vent. Should the sewage pit have it's own dedicated vent?

Screenshot 2021-11-02 101548.png
 
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wwhitney

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Up.codes says Indiana follows the 2006 (!) IPC, not the UPC.

In your diagram, the wye where the sink joins the drain is backwards.

And under the IPC, the sink drain can join either the toilet rain or the shower drain first, it doesn't have to be the shower (for the UPC it would).

Your washer will of course need a vent, not sure if that was already noted above.

Cheers, Wayne
 

Craig Alwine

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Up.codes says Indiana follows the 2006 (!) IPC, not the UPC.

In your diagram, the wye where the sink joins the drain is backwards.

And under the IPC, the sink drain can join either the toilet rain or the shower drain first, it doesn't have to be the shower (for the UPC it would).

Your washer will of course need a vent, not sure if that was already noted above.

Cheers, Wayne


Thanks Wayne! It may be a little less work in my situation to join the sink drain to the toilet drain and use the AAV at the sink. Is there a particular point between the toilet and the shower where the sink should tie in?

The sewage pit vent connects to the vent piping for the rest of the house. I've read the sewage put should have it's own dedicated vent. Is this true?
 

Reach4

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Washer standpipe will need a vent, which could be another AAV.

You may want a fair amount of the toilet path to go at 45 degrees, rather than just paralleling the house walls. Less digging, and nicer flow.

Your pit vent can join other vents on its way to the roof.
 

WorthFlorida

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The ejector pit vent just needs to be a dry vent either by itself or connected to the house venting. No wet venting allowed.

Since the pit was installed for mainly washer use, be sure the pump can handle sewage. It could be a sump pump in the sealed pit. It wouldn't hurt to inspect it for lint and hair with many years of washing machine use.
Screen Shot 2021-11-02 at 2.20.40 PM.jpg
 

Reach4

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To continue with that, the pump should be a "grinder pump", rather than an ejector pump, because it handles toilet solids.
 

Craig Alwine

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Tremendous help everyone....thank you! I completed the replacement of the sump pump with a sewage pump, replaced the -1 1/2" discharge pipe with a 2" discharge pipe as required, and cleaned out the sump pit really well. Testing the the new sewage pump with water I learned it pushes waste through with more force than the sump pump did. As such, I'm getting a gurgle and a smell in my upstairs kitchen sink when the sewage pump turns on and water passes by the kitchen sink p-trap. The force from the sewage pump is disrupting the water in the kitchen sink p-trap. The distance from the kitchen sink p-trap and the wye where the kitchen sink drain and sewage pump drain connect is pretty short, maybe 16". I ran some cleaner through the kitchen sink drain, replaced the AAV and the problem still occurs. I also ran the sewage pump without the kitchen sink AAV installed, the gurgling was less, but the problem still exists. I'm thinking I need to provide some distance from between where the kitchen sink drain and sewage pump drain tie into the 2" pipe that runs to the main line to prevent the waste from the sewage pump from disrupting the water in the kitchen sink p-trap. Please see my drawing showing my current connections and showing what I think needs to be done. Does anyone have any suggestions on how to remedy the gurgling and smell coming from my kitchen sink when the sewage pump turns on?
Screenshot 2021-11-03 101603.png


Important to note.....I did not have this problem with the sump pump when it was only pushing laundry wastewater through the drain.
 

Reach4

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What pump did you install?

To work around this, maybe increasing the trap depth in the kitchen would be enough. Max is 4 inches , measured from the top part of the bottom of the U and the bottom part of the trap arm, if I got that right.

Normally a sewage pit output goes up and then back down when joining other waste. I don't know the rule that prescribes how high is high enough.

Your sketch seems like a nice improvement. Could you increase to 3-inch downstream of the junction?
 
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Craig Alwine

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What pump did you install?

To work around this, maybe increasing the trap depth in the kitchen would be enough. Max is 4 inches , measured from the top part of the bottom of the U and the bottom part of the trap arm, if I got that right.

Normally a sewage pit output goes up and then back down when joining other waste. I don't know the rule that prescribes how high is high enough.

Your sketch seems like a nice improvement.
Thanks Reach4. I installed a 1/2 HP Barracuda Sewage Pump. I saw your note about installing a Grinder pump, but I've also read a Grinder pump is not a good idea when draining into a septic as it can create a sludge rather than a clear separation of liquids and solids in the septic tank. The Barracuda is rated for up to 2" solids so we'll see what kind of service I get out of it. Once the toilet is hooked up I intend to keep a close eye on it and if I need to pull the sewage pump and replace with a grinder I will. Increasing the trap depth would be a much easier fix than what I've suggested. Currently, it measures 2" so maybe I'll increase it to 4" and see what happens.
 

Reach4

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You could make an open manometer with some clear tubing to see how much suction is being developed at the kitchen sink. If you want more words on that, say so.

You want the pressure to be no more than 1 inch of water column. We know that it is more that 2 inches. You could measure, or just deepen the trap and hope.

It would be interesting to us, as well, to see how much pressure is being developed.
 
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wwhitney

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I suggest rerouting the pump discharge to the 3" main line and coming into it from above. I.e. pump up, then gravity drain to the 3" main line.

The problem you are having is a limitation of AAVs. The pump discharge is creating positive air pressure in front of it, pushing water out of the trap up the tailpiece, as an AAV is a one way valve to only admit air. If your sink had an atmospheric vent, the air pressure would go up the vent and protect the kitchen trap.

So the idea is to keep the discharge away from traps protected by AAVs.

Cheers, Wayne
 

Craig Alwine

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Problem solved! Thank you guys for your advice! In order to drop the pump discharge into the main line I had cut out the 2" run that the kitchen and pump discharge dumped into and extend my main line by 20' in its place. Good thing I did too because the 2" line did not have near enough slope. Surprised I didn't have any problems with it, but there was an awful lot of gunk buildup in that line. I dropped the upstairs kitchen sink near the end of the new 3" main line by the clean out and dropped the pump discharge about 8' past that. No more gurgle! Now one drywall and finishing.
 
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