How to Replace a Bathroom Sink Drain

Drainage issues in a bathroom are rarely just about the water; they are about the slow decay of metal parts that spend their entire life submerged in moisture. Over years, gaskets harden and threads corrode, turning a simple sink drain into a source of slow leaks or sluggish performance. Swapping out the drain assembly is a classic plumbing rite of passage that restores functionality and eliminates that pervasive, musty sink smell. Success in this project hinges on one thing: a clean seal. When you remove the old fixture, you must clear away every trace of old putty and mineral buildup before seating the new drain. If you rush the prep work, you will be back under the sink with a wrench within a week. Take your time, get the surface clean, and you will have a rock-solid, leak-free basin for another decade.

  1. Prepare Your Workspace. Empty everything from the cabinet under the sink and place a bucket directly beneath the P-trap. Loosen the slip nuts on the P-trap with your hands or channel-lock pliers to catch the water that spills out.
  2. Extract the Old Assembly. Unscrew the large nut holding the drain tailpiece to the bottom of the sink basin. Push the drain flange up from underneath and lift it out of the sink basin from above.
  3. Clean the Basin Opening. Scrape away all old plumber's putty and grime from the drain hole in the sink using a plastic putty knife. Wipe the area with denatured alcohol to ensure the new gasket will adhere perfectly.
  4. Apply the Seal. Roll a marble-sized piece of plumber's putty into a thin snake and wrap it around the underside of the new drain flange. This creates the primary waterproof seal between the metal and the porcelain.
  5. Secure the New Drain. Insert the new drain flange into the sink opening from above. From underneath, slide the rubber friction washer and the mounting nut onto the tailpiece and tighten them until the drain is firmly locked against the sink bottom.
  6. Reconnect the Plumbing. Slide the slip nuts and washers onto the P-trap arm, then reconnect it to the new tailpiece. Hand-tighten all connections firmly to ensure the pipes align correctly without stress.
  7. Verify the Seal. Fill the sink basin halfway with water and then pull the stopper to let it drain quickly. Inspect every connection with a dry paper towel to catch any small beads of moisture.