I live in a coop apartment in NYC and want to install a bathroom where a kitchen used to be located (the apartment has another kitchen and I do not need a second one!). The former kitchen is adjacent to an existing bathroom/powder room that will be removed. My questions are:
1. Can I tie into the old kitchen drain for (a) bathroom sink, (b) shower and/or tub, or (c) new bathroom toilet?
2. If the toilet needs to be tied into a separate riser, I could probably raise the floor and tie back to the drain for the existing toilet that is being removed. I read on another post that this can be done, but that the maximum distance is 10'. Is this a NYC requirement or a general requirement?
3. I assume that I cannot tie into the kitchen air vent system with a new bathroom, so I would need to tie back to the vent in the existing bathroom. Is there a maximum distance that applies here?
I understand that some of this work would need to be done by a professional plumber, but before I go down this path I would like to determine if there are any show stoppers. If anyone has done this before or has any suggestions, please let me know.
Thanks!
Bob

Hi Bob...

1) Kitchen drains are usually only 2", but in some states can be as small as 1.5" and as large as 3". A toilet requires a minimum size 3" drain pipe and the sink and tub connect into the toilet pipe. If your kitchen sink drain is 3" then you lucked out!!

2) NYC has specific codes and I can't guarantee the number but in my state the 10 foot maximum rule applies to 4" pipe, not 3" pipe. In my state, if you use 3" pipe then the vent must be within 8 feet of the toilet connection, maximum. Here, however, the vent connection must be within the 8 feet, but the vent can run quite a distance further if the proper pitch can be maintained and the vent connected back to the old vent (or up another wall to another vent). By the way, I'd recommend that you keep the vent within 3-6 feet maximum of the toilet connection for best vent/drain action.. ;)

3) A bathroom group in a home with more than one bathroom can usually get away with a 2" vent for the entire bathroom. In NYC, you may need to individually vent all the fixtures, but you would connect them all into a 2" vent pipe and connect that 2" vent pipe into another 2" or larger vent.

With that being said, if the kitchen sink vent is 2", you may be able to use it to vent everything.

You'll also want to check and see if WET VENTING is allowed in your area of NYC (some places allow some don't). Here, a wet vented bathroom is piped special in that it only requires one 2" vent for the entire bathroom... no individual vents, so it is a time/money saver if you can do it... it is a very specific plumbing design (see image).

There are maximum vent distances, but if you exceed them you can usually increase the vent pipe size one full pipe size and run the vent just about anywhere you want... :)

I have done some generalizing, so from here you'll need to consult your local code department for the specific details.

Hope that helps to get you started...

Mark