Bathroom sink plumbing. New Vanity, Sink, Faucet:

Bath Vanity and Lavatory: 
Part 2 - Connecting The Plumbing

In This Article: Related Articles:
Skill Level: 3 (Moderate) Time Taken: 2 Hours

By , Editor

More Plumbing:

Water supply pipes for lavatory sink. In the previous article, we had installed the supply stop valves, installed the faucet on the sink top, connected the supply hoses to the faucet, and glued the sink top to the vanity.


The supply hoses were connected to the stop valves. We used stop valves and supply hoses with 3/8" compression fittings.  Connecting water supply hoses for lavatory sink faucet.


There is just a little bit of slack in the supply hoses. 

Note the sink drain, at the top, and the drain pipe at the lower left. These need to be connected.


Sink Drain:

The sink drain parts. We bought an S-trap kit and a 1-1/2" extension tube. This assembly connects to the slip-joint adapter fitting that we earlier glued to the PVC drain pipe.

An S-trap is used when the drain runs down through the floor. If the drain pipe runs horizontally into the wall, a P-trap is used.


The sink stopper pop-up lever was installed in the sink tailpiece extension. (Moen calls this piece the drain body.)


The pop-up lever is held in place with a special wing-nut threaded cap. We're just testing the fit, it's too early to assemble this.


The drain body has a white plastic gasket or sleeve to seal the connection with the tail piece.


Ooops Again!

Looky here... the drain piece (and all that silicone sealant) had to be removed, and a ring of plumber's putty installed.

Why? Because we forgot one thing... the threads on the tailpiece prevented us from positioning the drain body the right way. In order to get the pop-up lever pointing to the back, we needed to rotate the tailpiece another 1/2 turn or so. But not with silicone sealant holding things in place.

On other types of drain basins (such as kitchen or laundry sinks, showers and bath tubs) there is no pop-up that has to point a certain way, so the rotational position of the tailpiece does not matter. In those places I prefer to use silicone for a sealant.

But.. Plumbers Prefer Plumber's Putty:

I'll agree that most plumbers seem to prefer plumber's putty, but I believe it is an ancient material that has been surpassed by modern materials, such as silicone. Too many plumbers spend their time doing primarily new construction work, and do not spend enough time doing repair and maintenance work to see the consequences of their chosen materials. I have seen numerous leaks that are the result of plumber's putty and it's non-adhesive properties. I just replaced a kitchen sink drain basket that I installed only two years ago... because the threaded metal locking ring had snapped, which allowed the drain basket to move, which broke the seal formed by the putty. But silicone caulking in that same situation would probably bond the parts together and prevent the leak.

The primary benefit from plumber's putty, from my perspective, is that you can assemble some parts and then use them right away. With silicone you really must wait an hour until the caulking has at least skimmed over, but it's best to wait 24 hours until it has fully cured.


Installing sink tailpiece. The tailpiece is pushed into the putty. The excess goo is easy to wash off.


The big nut underneath was just hand-tightened. 

That black rubber washer is the part that does all of the sealing in this type of drain. If the plumber's putty were to leak, all that would happen is water would be able to get into the same place where the overflow tube brings excess water... right back into the drain. (See the previous article for a photo of this concept.)

Fastening sink tailpiece.


Bath sink drain body. The drain body was installed, and the tailpiece was turned so the lever pointed to the back.


Once the pop-up lever was pointing the right direction, we tightened the big nut with a large crescent wrench. It is actually quite easy to bend the big flat washer if you are not careful.


Pop-up Drain Stopper:

Bath or lavatory faucet stopper hardware. The pop-up drain stopper parts. This only looks confusing.


The vertical piece connects to the trip lever with a spring clip. 


The visible part of the pop-up connects to another piece under the sink. This photo is only to show how the parts go together... the actual connection must be made behind the basin. 


We put a little silicone grease on the pop-up trip lever ball. 

This is not the same as silicone caulking or silicone spray lubricant (like WD-40). This is a thick, gooey grease product specifically for lubricating plumbing parts. It will not attack the rubber seals in valves, and water will not wash it away.


The lever was installed in it's socket, and the linkage was connected.

The pop-up rod was connected, behind the basin.


The S-trap is all that remains.


The S-trap was installed. The slip-joint fittings make it easy to install this section. The slip-joint nuts are only (firmly) hand tightened.


Wahoo !

The water runs.   The water drains.   Nothing leaks.


The cabinet door pulls were installed.


The vanity and sink are done.

We found it necessary to run the water for about half an hour to flush out the odor from the solder flux used in the new copper pipes. It is important to frequently check for leaks at this point, as this is when they are most likely to show up.


Other Related Articles:

Installing a large multiple-piece vanity.

Installing a laminate vanity counter top, and cutting the hole for the sink.


Tools Used:

  • Adjustable Wrenches
  • Channel-Lock Pliers
  • Screwdrivers


Materials Used:

  • Braided Flexible Faucet Supply Hoses
  • S-Trap Drain Kit, 1" Diameter
  • Plumber's Putty
  • Silicone Grease


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Copyright 2000, 2005

Written August 9, 2000
Revised January 3, 2005