Unless you have a really weird setup the sinks join in the cabinet and then go into one drainage pipe. The same for the water lines. One set (hot and cold) come into the vanity then split for both sinks.

Count mine as really weird then! (and on only a 54" vanity!)

I definitely have 2 drain lines, and 2 sets of supply lines for my double vanity. I will be interested to hear what the OP has.

You will need to make a couple slight alterations however it is impossible to know for sure what you will have to do until the wall is opened up and we can see the present layout of the water & drain lines. The good news is that even if you have to make alterations, they are very simple and certainly well within the skill level of an experienced DIY'er.

NOW AS TO WHETHER YOUR INSTALLATION IS WEIRD?

(See attached illustration)

Assuming that the two sinks were put in to code it is not nearly as weird as Hendricus would have us believe.

Under both the UPC & IRC if the horizontal center to center distance between the two drain openings does not exceed 30" they may be combined in the same manner as connecting a kitchen double sink, then connected to a single trap & waste arm.

Under the IRC if the CTC distance exceeds 30" you may attach a double wye on the waste arm and run a separate line to each trap, with a cleanout on the end of the WYE, Providing the TDL (total developed length of either drain does not exceed the code mandated maximum trap weir to vent opening distance.

Under the UPC if the horizontal distance exceeds 30" each sink must be provided a separate fixture arm. (UPC prohibits connecting two traps to one fixture arm).

lazypup thank you for all the illustrations. We are planning to get a look behind the wall this weekend. But from what I can see so far, our sink looks like the UPC greater than 30. If this is the case, should we cap the second sink waste line? Or can we cut them both bank to the central line and rebuild one from there? I have absolutely no plumbing experience so I apologize if I need things explained to me like a 5 year old.

I would love to tell you that you can just cap those lines then install a fixture arm stub out where you need it, but I cannot give you a finite answer until we know where the vent is connected.

If I might suggest, as soon as you have the wall opened up take a picture of the layout and email it to me. I will then be able to see how the lines run and where the vent is connected, then I could give you a final answer. Also try to get the water supply lines in the photo and I can advise you how to correct those as well.

Email to LaxyPup@Yahoo.com

I check my email a half dozen times a day so I should be able to get a quick solution back to you and I will then post the solution so others watching this post will be able to see the results.

Silly me...I seem to have a typo on my own email address above..

LazyPup@yahoo.com

Sorry for not responding anytime sooner. I got a bad case of the flu and had to hold off taking out the vanity. Unfortunately, before we could take out the vanity, a pipe burst in the bathroom and flooded it, the downstairs kitchen, and my basement. We are in the process of getting the insurance to come look at it and hopefully pay for some of the damage. We are going to have our contractor change the plumbing out so we don't have to worry about doing the conversion from double to single ourselves. I really appreciate all your input, esp. lazy pup. That diagram was awesome and really helped me to understand what was going om under our sink. Here are some pics from our flooded house:

[IMG]http://i41.tinypic.com/347tro2.jpg[/IMG]

[IMG]http://i43.tinypic.com/chv85.jpg[/IMG]

[IMG]http://i42.tinypic.com/4ftyiq.jpg[/IMG]

[IMG]http://i44.tinypic.com/10z8mfl.jpg[/IMG]

[IMG]http://i39.tinypic.com/1zgge2e.jpg[/IMG]

dude, Calyptra's post is three years old; I just "bumped" it to find it, because there's very, very little I can find here or on the Internet in general about converting from two sinks to one.

I need to know too!

My master bath re-do began with a double vanity / sink combo in the bedroom with a toilet and walk in shower in a separate room off to one side and a gigantic roman tub in a separate (but not closed off with a door) area to the other side. The vanity was one of those oak front particle board pieces of garbage with a cultured marble double sink and one of those gigantic mirrors overall. The walk in shower (which began the whole re-do) leaked underneath (inaccessible, of course) and into the kitchen below. So. Now I have a toilet and single wall sink with cart instead of vanity in the room where the toilet and walk in shower was. The roman tub (which was too big to be filled by our standard sized hot water heater) is replaced with a freestanding tub and shower combo (shower curtain all around) with easy-access plumbing (i.e. easy to spot leaks). In the center area that is part of the bedroom is just a freestanding mirror and a hanging plant under the skylight. Very minimal, clean, private. There is a little "ledge" under the free-standing floor mirror covering the plumbing that ran across the floor to the tub. This is reflected also by the ledge in the bathtub/shower area that was always there. It also prevents bashing into the unframed but beveled mirror with the vacuum cleaner. I know this is a lot to picture so I will try to come back with photos later. We are still doing some painting. It always seemed icky to me to have sinks in the bedroom and stupid to have a shower separate from the tub. Capping the lines from the double vanity and converting the shower plumbing to sink plumbing was fairly quick and easy (took a plumber less than an hour). I would suggest you hire a professional for the plumbing and do the rest of the job yourselves if you are wanting to go the diy route.

I bumping this as well. We are moving into a new build home (it was an inventory home) and there are no linen closets in the bathrooms so we also need to convert a double sink to single with towers and drawers. It is really hard to find any info for this kind of conversion.

One reason that its hard to find a definite answer is that it depends on the layout of the existing plumbing.
- If you have two properly vented P-traps and wall connections (one for each sink), and you can cap one of them without the new cabinet being in the way, this should be a simple solution. You also need to cap the supply lines.
- If you have only one connection to the wall, and it can be reoriented to connect to the new sink, that should be easy to implement. You will still have to cap the supply lines.

This is one case where its much easier to just call a plumber if you don't have the skills and knowledge yourself. It is likely to be a simple job for a qualified plumber, but they still have to get a reasonable wage for the work (in other words, it may still cost $200+ for labor). If it turns out to be complicated, you need the plumber anyway to figure it all out.

Buce

Found this old thread, hoping someone can help me with the same question and I have a photo showing what is going on. Can I cap the water lines and drain on the right, then cut/move the left side water lines and drain to the middle for the new center/single sink I'll be installing? Or is it best to not cap? There will be access behind the new cabinet if shelves are removed. Thanks much!

Old thread but thought I'd add our two cents. We moved into a house where the master bath had two pedestal sinks and zero storage. So we pulled out and sold one pedestal sink and are replacing it with a hutch for storage, counter space, etc. We are leaving the water supply in as the hutch will cover it up, plus it's good to have that extra plumbing ready to go for resale value (even if you think you'll be there forever, life can happen and these little things are nice to have kept).