Adding a utility sink to garage

[JTAFVet]

Hello. I would like to add a utility sink in my garage but I am not sure how to properly connect the drain so it will drain correctly and meet code. The sink will be installed against a wall where on the other side of the wall is the master bathroom. Please see image to see my current setup and not so good drawings with options I thought.
I would appreciate if someone could please let me know if any of these would work and be code compliant in San Antonio, TX. Thank you in advance!

 

[MicEd69]

I believe you are under the IPC code, so what's shown below MAY be applicable.


This shows a washing machine standpipe, but the inspector MAY deem that this design is applicable to your water softener drain.

If not, tying your utility sink into the horizontal drain from you master bathroom sink would work. But a better design would be to stack another Sanitary tee on top of the existing one draining your master bathroom sink and drain the utility sink into that one.

 

[JTAFVet]

I believe you are under the IPC code, so what's shown below MAY be applicable.
View attachment 47948

This shows a washing machine standpipe, but the inspector MAY deem that this design is applicable to your water softener drain.

If not, tying your utility sink into the horizontal drain from you master bathroom sink would work. But a better design would be to stack another Sanitary tee on top of the existing one draining your master bathroom sink and drain the utility sink into that one.

Thank you very much for your response. It looks like I’m going to go with tying the utility sink into the horizontal drain from the master bathroom sink since it is allowed and it’s the most simple way of doing it. I would have gone with your better design but I can’t because then the drain outlet would be to high for the deep utility sink. Thank you again!

 

[GReynolds929]

Option 1 is your best bet, you can't tie into another fixtures trap arm/drain before its vent connection. The horizontal drain from the master is a trap arm and cannot be shared or tied into as it has not connected to its vent yet.

 

[MicEd69]

The horizontal drain from the master is a trap arm and cannot be shared or tied into as it has not connected to its vent yet.

I'm not sure I understand from where this statement is coming. While the pictures below are kitchen sinks, the principle still applies to this situation.

 

[JTAFVet]

Option 1 is your best bet, you can't tie into another fixtures trap arm/drain before its vent connection. The horizontal drain from the master is a trap arm and cannot be shared or tied into as it has not connected to its vent yet.

Thank you for your response! I have a question if I proceed with this method. While reading the code, I came across the following section: “802.4.3.1 Connection of laundry tray to standpipe. As an alternative to a laundry tray fixture directly connected to a drainage system, a laundry tray waste line without a fixture trap shall connect to a standpipe for an automatic clothes washer drain.”

In this section, it mentions “without a fixture trap.” Does this imply that I cannot install a P-trap under the utility sink? Will this be equivalent to double trapping? I would greatly appreciate your clarification on this matter. Thank you in advance for your assistance.

 

[MicEd69]

Yes, you are correct that you cannot install a double trap. See the drawing in my response #2 above. The P-trap in the washing machine standpipe, or the water softener drain in your case, will protect the sink and the water softener standpipe from emitting sewer gases to your residence.

 

[GReynolds929]

Yes you would not have a trap under the utility sink/laundry tray or it would be double trapped.

 

[GReynolds929]

I'm not sure I understand from where this statement is coming. While the pictures below are kitchen sinks, the principle still applies to this situation.

View attachment 47957
View attachment 47958
View attachment 47959
View attachment 47960

In my area under UPC 1001.2 those are all prohibited installations. This was a common way to plumb sinks back in the day and is still gotten away with today. It is illegal by my code though, and takes up unnecessary space and materials in my opinion.

https://epubs.iapmo.org/2018/UPCITM/#p=314

 

[MicEd69]

In my area under UPC 1001.2 those are all prohibited installations. This was a common way to plumb sinks back in the day and is still gotten away with today. It is illegal by my code though, and takes up unnecessary space and materials in my opinion.

https://epubs.iapmo.org/2018/UPCITM/#p=314

Interesting and wow. IPC doesn't seem to have those prohibitions. I agree that plumbing a kitchen sink that way isn't the best, but I can't see where adding a sink drain to an existing sink drain line would cause any problems. And the OP is under the IPC code.