Hi, folks -

This is my first time posting on a plumbing subject. I'm a homeowner who is usually pretty handy, and I've done quite a bit of plumbing repair around my house. However I have a little bit of a problem with a project I just did.

I have a full bathroom in our basement, but the sink was in an awkward place, and I decided to relocate it to the other side of the bathroom (about 9 - 10 ft away from the original location). I ran new water supply lines (copper), and a new drain pipe (sch. 40 pvc), and tried to pay attention to the pitch of the drain pipe. The water supply is working fine, but the sink drains extremely slowly - like, it takes over an hour to drain when it is full.

The drain runs into the same (under slab) waste pipe that it ran into before (by the way, the tub/shower also drain into this waste line and don't have a problem), so I assume the venting would have to be okay. My guess is that it has something to do with the length of the new drain pipe and the number of turns (it runs along the wall and makes four 90 degree turns before dropping down vertically to the underslab waste line, so all together it probably is about 15 or 16 feet of pipe).

Short of ripping everything out and putting it back the way it was, is there anything I can do to correct the situation? I've heard of some kind of mechanical vent, but I don't know if that will work in this case, and I don't know anything about them to know what exactly I should be looking for. Can anyone give me some advice / guidance?

By the way, the drain piple in question is 1-1/4 inch.

Thanks for your help!

Let's see,
A 16 foot 1 1/4" drain that has 4,( count em!!) 4 ninety degree bends in the line plus a question about the vent and you're asking why it drains slow.
Let me count the ways.
1- If the sink drain line goes into the floor instead of the wall you have a "S" trap and the drain's unvented.
2- The drain line should be 2" with 1 1/2" minimum.
3- Bends and 90's cut down on the drain flow. If you must have bends in a drain line make them sweeps or two 45 degree ells not a sharp bend 90.

You can try cutting in a tee downstream of the trap and installing a AAV,( Air Admittance Vent) to relieve the suction set up by the flow.
Good luck, Tom

You can try cutting in a tee downstream of the trap and installing a AAV,( Air Admittance Vent) to relieve the suction set up by the flow.
Good luck, Tom


Okay, thanks for the advice. I'll give that a try and hope for the best. Is the AAV something I can get at a place like Home Depot or Lowe's, or do I need to go to a plumbing supply store for that? Also, do you have any idea if that will be a code problem in New Jersey?

I appreciate the help.

Cheers,
LD Robinson

Okay, thanks for the advice. I'll give that a try and hope for the best. Is the AAV something I can get at a place like Home Depot or Lowe's, or do I need to go to a plumbing supply store for that?

Just ask for a Studor Mini-Vent (http://www.studor.com/index2.htm) in the Plumbing section of your local Loews or Home Depot.


Also, do you have any idea if that will be a code problem in New Jersey?


You're going to have code issues on this one no matter where you're located.

The drain needs to be a minimum of 2", the trap and trap arm needs to be a minimum of 1-1/2", you're allowed only one 90 degree change in direction on a trap arm and are limited to 42" on the developed length of the 1-1/2" trap arm.

Trust me, the legality of the AAV is the least of your worries.

You're going to have code issues on this one no matter where you're located.

The drain needs to be a minimum of 2", the trap and trap arm needs to be a minimum of 1-1/2", you're allowed only one 90 degree change in direction on a trap arm and are limited to 42" on the developed length of the 1-1/2" trap arm.

Trust me, the legality of the AAV is the least of your worries.


Thanks, Growler. Now I know why the sink was where it was, as lousy a location as it was.

Thanks, Growler. Now I know why the sink was where it was, as lousy a location as it was.

Hey, this isn't completely beyond salvation if you intend to live there long enough to enjoy the use of the bathroom.

Try the AAV -- Allowing a bit of suction on the line just might make the situation tolerable.

Of course the ethical Plumber in me urges you to make a full disclosure of the situation if and when you decide to sell the place.:D