I'm trying to lay everything out for my new bathroom in the basement and I still have a few questions. Someone on another board drew a great diagram for me, but when I was at the hardware store trying to figure out how it would actually be laid out, it seems like if I put a 90 at the end of my new line, then Y on top of that to the WC, the new line is going to have to be pretty far underground... and I'm guessing my existing sewer line isn't that far underground since I'll be so close to my stack. I'm also trying to keep all the vent lines coming up along that same line, where the back wall of my bathroom will be built. The first pic is the one he drew, then I modified it so that I wouldn't have to bury the new line so deep... but I'm not sure if the WC is properly vented then. Any other suggestions on how I should run everything?

Here's what I originally drew up for my bathroom design... you can tell I'm not a plumber.

The toilet will be wet vented through the lavatory vent. The new floor drain should be reduced to 2"and will not require a separate vent. All your vents may be revented back to a existing dryvent which runs out the roof. Good luck, Tom

Tom, can I run the WC like I drew in pic Iso1? Or does it have to be like in pic iso2? Thanks for the help. Also, when my friend did his, when he got his permit, they told him every fixture needs its own vent.

Here's what I originally drew up for my bathroom design...you can tell I'm not a plumber.

Speedball is right, the trap arm for the floor drain should be reduced to 2", and depending on the rules of your local authority, may not need to be vented at all.

As for the water closet and lavatory drain and vent, put a 3"x2" Wye between the floor drain wye and the water closet wye to pick up the lavatory.

I've attached a revised photo, but be advised that the line drawing portion of my certification exam was a train wreck.

Hmmmm...

My attachment didn't attach.

I'll try it again.

The vent should come off the 45 branch of the wye vertically by putting a street 45 into the 45 branch of the wye, directly under the wall, not the back end of the wye.

Growler, Welcome back. I'm looking at the toilet vent you've added. You have one 3 X 2 wye picking up the lav but I fail to see the second wye that you speak of, and if there's anotherwye it has to be rolled up 45 degrees for a dry vent such as you've drawn. Or am I missing something? Glad to see you back. Stick around.
1990,
Do the codes in your area allow wet vents? If so I would go with iso1 only pick up the the toilet with a side inlet closet bend and wash it with the lavatory. Tha way the toilet will be vented by the lavatory. Also check to see if a vent is mandated on the floor drain. Cheers, Tom

Growler, Welcome back. I'm looking at the toilet vent you've added. You have one 3 X 2 wye picking up the lav but I fail to see the second wye that you speak of, and if there's anotherwye it has to be rolled up 45 degrees for a dry vent such as you've drawn. Or am I missing something? Glad to see you back. Stick around.
1990,
Do the codes in your area allow wet vents? if so I would go with iso1 only pick up the the toilet with a side inlet closet bend and wash it with the lavatory. Tha way the toilet will be vented by the lavatory. Also check to see if a vent is mandated on the floor drain. Cheers, Tom

The second wye is a 3x2 looking straight up with a long sweep 3" 90 coming out the back end aimed horizontally towards the toilet location immediately after the 3x2 wye that is picking up the lavatory.

No wet venting allowed up here in Washington -- And most inspectors will no longer allow previous examples of wet venting to remain -- All previous work must now be brought up to new code requirements.

As for the vent on the floor drain, he probably doesn't need one, but since the option to install one exists, the inspector will most likely make him put one in.

Hey! With all those extra vents it doesn't hurt to ask about wetventing. In my area we still wet vent our bathroom groups. This leaves just one vent instead of three, (unnecessary in my opinion) vents. Regards, Tom

It's funny, but you never really know what the local authority will expect until you ask them.

I've worked in Alaska, where wet-venting is perfectly acceptable.

Worked in Boston, where wet-venting is allowed as a last resort (I blame the Silva family for the accepted dumbing down of sanitary code in all of New England)

And then I've worked in California, Oregon and Washington, where wet venting is forbidden in all cases.

Things would be a lot simpler if everybody could decide on one standard.

Even here in Washington we can have practices that are acceptable in one municipalty, but are absolutely forbidden just a few miles away in another municipality.

Basically, if I'm plumbing in an area I've never worked in before, I make it a point to meet with the local authority before starting the job.