Adding a new line to existing drain

[Jofai]

Hello all! I'm looking to add a drain line for a new water softener to my existing drainage system. It happens that where I'd like to install the new drain is right on the other side of the wall from an existing bathroom, and I'd like to tap into the drain line for the tub.

Here's what I'm thinking of doing:

Is adding the extra line like this necessary, or could I perhaps go directly into the existing tub line via a sanitary-tee? I think it's required that I have the new trap for the stand-pipe since they're different fixture types (as opposed to something like a double-basin sink), which is why I'm thinking this way is correct.

If I go the diagramed route, is wet venting this way sufficient, or do I need to also connect the vent line:

Any advice appreciated. Thanks!

 

[Jofai]

I've just realized that the second vent-line option is not a real option, since the connection isn't made 6in. above the flood rim of the tub/stand pipe entrance. Dang!

So I guess my question is: can I tap in below the existing vent like that?

 

[Sponsor]

 

[Tuttles Revenge]

Each fixture must be trapped to keep out sewer gasses. Each trap must be vented to prevent siphonage and maintain the trap seal. Each vent must connect no less than 6" above the flood level of the higher fixture to prevent a clogged drain from overflowing via its own vent down the vent and drain of the other fixture.

Only fixtures on the same floor can wet vent together (special rules for wet venting either horizontally or vertically)

So you would need to tie in the drain of the new fixture downstream of the vent connection of the existing fixture. Either on the vertical or horizontal. The new fixtures trap must be vented and connect above the flood level of either fixture.

 

[Jofai]

Thanks for the response. After reading through the venting UPC, it looks like maybe the right thing to do is a system like this:

I'd go into the vertical stack there, but it's pretty tight, with the existing long-sweep wye going almost directly into the vent sani-tee:

Does that make sense and meet the UPC? I think it does after reading through and attempting to understand chapter 10.

 

[Jeff H Young]

softener drain isn't technically allowed to be wet vented horizontally not part of a bathroom group

 

[Jofai]

I see. Is my only to-UPC option to run a completely new vent then?

The only thing it's sharing the vent with is a rarely (...a couple times a year?) used bathtub. Everything down-stream of it has its own dry-vent plumbed in. I'm a little loath to try and run a completely new vent in this circumstance, but understand if that's the only to-code option.

 

[Jeff H Young]

now that I think of it you might be legal to wye off that tub drain above the ptrap . its a 2 inch trap I would think a 2 x2 x1 1/2 santee cut in and piped over through floor without a additional p trap would work perfectly. Though its uncharted territory for me good chance something about that's not code basically its just like we run condensate except normally its to a lav. if not I'd like to hear why

 

[Jofai]

Thanks a bunch for the insights. Wouldn't that violate UPC 1001.2? "Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap." I guess that kind of depends on the definition of "fixture" here, but I think it'd count for a drain intended for water softener discharge (I'm no expert though!)

I think in reality for my situation (with a rarely used fixture) it might actually be better as I can be sure the trap won't evaporate out since the softener will run water through it at least 1x / month.

If the only reason not to do the horizontal wet vent (and really, it's horizontal for < 1') is because a water softener doesn't belong to a "bathroom group" I think I might go that route. It seems like maybe that's the closest I can get to meeting code without running a totally new vent, unless I've missed something.

 

[Jeff H Young]

w

Thanks a bunch for the insights. Wouldn't that violate UPC 1001.2? "Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap." I guess that kind of depends on the definition of "fixture" here, but I think it'd count for a drain intended for water softener discharge (I'm no expert though!)

I think in reality for my situation (with a rarely used fixture) it might actually be better as I can be sure the trap won't evaporate out since the softener will run water through it at least 1x / month.

If the only reason not to do the horizontal wet vent (and really, it's horizontal for < 1') is because a water softener doesn't belong to a "bathroom group" I think I might go that route. It seems like maybe that's the closest I can get to meeting code without running a totally new vent, unless I've missed something.

what about an A/c condensate line thosealmost always connect to a lavatory tailpiece? Ive never done a softener tis way I ve connected them to sinks many times though. My preferance would be whichever is legal. another thing to look at is a "standpipe" for a washmachine calls for trap to be above the floor andyou might verify this standpipe requirement. so it might be breaking a second code too.

 

[Jofai]

Yeah, I'm not sure about how the A/C line fits in there. I'm definitely not a pro

My preferance would be whichever is legal

Me too! I'm just having trouble reconciling what would actually be legal hah. Any ideas what the right way to figure it out would be? Normally I think the process would be to pull a permit and get an inspection, but perhaps I should just reach out to my city's planning division? A permit seems like pretty big overkill for < 5' of pipe hah.

I did see the washing machine clause (UPC 804.1). It says:

No trap for a clothes washer standpipe receptor shall be installed below the floor

After trying to look around and understand the reasoning behind that, the best I've been able to find is that it's to allow for easy maintenance, since clothes washer discharge is prone to causing clogs because of all the debris in it. I'm not sure if that's actually accurate. Between that logic, and the fact that it's certainly not for a clothes washer... I'm not sure? Definitely shaky like you say though.

Thanks again for your input!

 

[Jeff H Young]

Yeah, I'm not sure about how the A/C line fits in there. I'm definitely not a pro


Me too! I'm just having trouble reconciling what would actually be legal hah. Any ideas what the right way to figure it out would be? Normally I think the process would be to pull a permit and get an inspection, but perhaps I should just reach out to my city's planning division? A permit seems like pretty big overkill for < 5' of pipe hah.

I did see the washing machine clause (UPC 804.1). It says:

After trying to look around and understand the reasoning behind that, the best I've been able to find is that it's to allow for easy maintenance, since clothes washer discharge is prone to causing clogs because of all the debris in it. I'm not sure if that's actually accurate. Between that logic, and the fact that it's certainly not for a clothes washer... I'm not sure? Definitely shaky like you say though.

Thanks again for your input!

The p trap on a washing machine of a modern home is accessible less than 1 percent of time they are buried in drywall every time. some of the codes I don't even try to figure out why, except when there is a deviation and deciding whether it needs correcting and at how great an inconvenience.
I don't remember seeing anything about other "standpipe" requirements just mentioned in case there was something.
I think length of run, size of piping, would have bearing as to whether wyeing off the tailpiece to the existing 2 inch ptrap would fly. But I see no issue functionally and personally prefer it by far over a horizontal wet vent. Kind of hate to give it my full support because Its not something I've seen much of.

 

[Jofai]

Kind of hate to give it my full support because Its not something I've seen much of.

Yep, totally understand. Thanks for the input, much appreciated!