Opinion on Drain Placement

I'm on the last leg of a bathroom remodel (DIY). The last thing to do is put in the vanity and sink, but I need some advice on drain setup. I've got a pic here of my situation, a looking up view in the basement where the plumbing will be done.

In RED is the easiest, original plan, where the drain comes through the black spot, and connects to the PVC marked A. This connection is all needed to finish the plumbing, the rest is already in place The PVC shoots to the right just over 8', and then heads to the big black main sewage line through another 19". Right next to the elbow at the end of A (not shown) is the vent line to the roof.

Option B in blue, is the more difficult option. The line is much shorter, only a 19" trip to the sewage line, however, it involves cutting the black main sewage line. Also, the person that recommended that also recommended adding a vent to the black sewage line through the same T connection.

The sink is in a bathroom, and if we do Option A, the only drainage competition on the line before the sewage line is the bathtub/shower, which, there is little foreseeable reason for the sink and shower to drain at the same time.

A "vent" at the "black pipe" will be cosmetic and do absolutely nothing, but, from your description of what you want to do, it appears that you will NOT have a vent on the sink drain, which is also illegal.

quote; there is little foreseeable reason for the sink and shower to drain at the same time..

Draining at the same time is NOT the problem, The problem occurs when either one drains by itself.

Ok, so it seems like you're saying go with option A, but there needs to be a vent, here's a picture of the place where the sink drain will connect to the black pipe. I've marked where the Red A line comes in and the black pipe. the yellow circle is a vent to the roof, I don't know if that's enough to satisfy the legality.

There's more wrong than right in that picture. I don't know where to begin...

Wow. This is a good example of why people should ask for knowledgeable assistance before they start a project.

Do some reading. Each PVC drainage fitting has a specific purpose. Each vent fitting has a specific purpose. Every fixture must have a trap, and every trap must be vented within a specific distance. The good news is that it won't cost much to throw all that stuff away and start over.

Actually, Lemiwinks, I think you are telling us that what is there is what was already there before you started? Like all you are changing is the sink drain, and your toilet and tub drain aren't being changed or haven't been changed? If so, what is already done has some problems, as the pros have noted.

Have a look at this guide for homeowners, particularly regarding venting stuff. I'm not sure how that tub drain is being vented, don't see your toilet in the pictures, and don't see how you are planning on venting the lav (sink) drain. In some jurisdictions, you can "wet vent" a lavatory grouping on the same floor, and in some places that wouldn't be allowed. Here, it looks to this only-marginally-knowledgeable eye that at a minimum the tub drain isn't properly vented and you don't yet have a good plan on venting your sink drain.

This guide gives you some ideas of how it all goes together:
http://www.klickitatcounty.org/documentcenter/view/103

And this one has photos showing a number of ways things can be handled and how each PVC piece can be used properly (kind of like applying the rules from the other guide -- these are nice photos of properly-done installations that illustrate how one complies with the rules):

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

Pretty much correct, I'm doing what I can to make use of the existing setup, nothing changed with the toilet, the sink is a new drain, and the shower is making use of the old shower drain, the vent and shower were pretty much where they are now. The sink hasn't been put in yet, in fact, i haven't cut the hole in the floor yet. This post started with the main question of how to install the sink, my uncle suggesting option b, and his way would have a T off the black pipe, and the T would connect the sink drain, and a new vent located basically where the blue marking in the first picture is. Otherwise the tub and the sink would have the same vent.

I realize there is a lot wrong in the picture, but I have to compete with my father's stubbornness in not hiring a pro to do it, so I'm doing the best that I can with what fights I win against him... The PVC work is all his, the pex is my fix on his really bad copper plumbing system...

I'm definitely going to check out the guides you posted, any particular sections I need to focus on? I just want to finish this bathroom so it works and wont blow up my house.

1. The sink trap should be above the floor.
2. The vent should connect ABOVE the trap which is above the floor
3. That "yellow" vent is NOT done properly, besides apparently having back pitch.
4. You appear to show a tub drain which does NOT have a trap.
5. It seems ALL the connections to horizontal drain lines are done with sanitary tees
6. Someone apparently mixed ABS and PVC fittings. I wonder how they got them to stick together and STAY together.
7. These are just the obvious violations in the small area your photo shows.
8. Bad plumbing, at least bad drain lines, do not "blow up the house", they just make you sick and kill you slowly.
9. From your first photo, it looks like the same guy who did the plumbing also did the electrical work.

Hit the nail on the head.... dad did the electrical too....
#1, 2, 3, 4 I figured out from the pdfs wjcandee posted, though I'm not looking forward to cutting into my wall that I just finished to add the vent for the sink...
#5, I get what you mean, whats the proper use of the sanitary Tee, and when should I use it vs a regular Tee
#6 What are you seeing as ABS? the main black line is actually painted PVC, I just went and looked, only half is painted and I can read PVC on it. And the black fittings are the flexi rubber booties.

On #5, I think the point is that the San T on its back isn't appropriate for a drain connection. Look at page 8 of the Lincoln County handout. When you're connecting a vertical drain to a horizontal, you can't use a San-T horizontally; you need something that's going to give direction to the flow -- so the proper fitting is a Combo Y-1/8-bend.

Alright, so i feel much more enlightened, basically I need a trap on every drain, all drains need a clear path from a point vertical to the trap leading to vent. Sanitary Tees should never be in horizontal positions. All pipes need a downward pitch towards the sewage line.
1. Is there a max distance for a vent line before it goes vertical?
2. Is there any way to install my sink without cutting a hole in the wall and running a vent pipe?
3. Clarify "San-T horizontally", is this saying that the straight part of the Tee can't be vertical? Because the Klickitat pdf drew quite a few this way so I want to be sure I understood that
4. Can I send the drain from the sink straight into the basement, put the trap on, in the basement, and then Tee off tot he vent and sewage?