Often the source of a leaking lavatory underneath the lavatory basin will be a leaking drain trap. Closely following in second place are the faulty connections between the lavatory basin drain and the lavatory drain line also called the "tailpiece". This article will offer some tips to help you fix your leaking lavatory drain.
Finding a leak in a lavatory
Before you grab the phone to call a local plumber you could try and fix the leak yourself, To find the leak in the lavatory drain, take a look up towards the connection between the drain body and the tailpiece, there is a lock nut connection securing the tail piece to the lavatory drain body. If the outside of the locknut connection is wet, then it's the drain body that is has a leak in it.
Removing the lavatory drain trap
To properly remove the trap bend (the U-shaped part of the pipe in the drain line), start by placing a bowl or bucket underneath the trap bend. If the trap has a cleanout plug on bottom of curved section, use the wrench to remove it, and let the water run out of the trap. Then loosen the slip nuts located above the U-shaped trap bend on both sides of the bend, using a wrench. The trap bend will then drop down into the bucket along with any water inside the trap.
Removing the lavatory tailpiece
The "tail" piece is the straight piece of pipe just above the trap bend that connects the p-trap with the lavatory drain body. To properly remove the tailpiece, slide the trap's nut and washer off the tailpiece, and remove the tailpiece by unscrewing it from the fitting using a wrech.
Removing the lavatory drain control
The drain control will need to be disconnected from the tailpiece using the proper plumbing tools before you can start with removing the drain assembly. You will need a wrench to loosen the screw and free the rod. Then take the pivot rod out of the drain. After that disconnect the pivot rod from the pop-up stopper, and remove them both.
Removing the lavatory drain
Use a wrench to unscrew the locknut below the drain body to disconnect the drain assembly. (turn the lock nut in a counterclockwise direction)
Reinstalling the lavatory drain and tailpiece
After the drain assembly has been properly disconnected, it must be resealed by using so called plumber’s putty. From underneath the lavatory basin, replace and secure the locknut to hold the drain body in its position, after that you can reconnect the tailpiece to the drain body and tightening the slip nut between the tailpiece and the drain body.
Reinstalling the lavatory drain controls
To reinstalling the lavatory drain controls you first need to attach the lift rod to the clevis pin. Then insert the pop-up stopper into the lavatory drain body, and engage it with the pivot rod. Adjust the elevation of the stopper by selecting the appropriate hole. Then reattach the spring clip.
Reinstalling the drain trap
Slip the P-trap washer and slipnut back onto the tailpiece. Reconnect the trap bend to both the trap arm and the tailpiece, once everything is properly positioned, tighten both nuts with a wrench.
Check if leaks are fixed
Let the putty dry, and then run water through the system to check for leaks. Tighten the nuts further, if necessary.