Gather the sink drain parts, plumber’s putty or silicone, wrench, and towel
Remove the old drain if replacing one
Clean the sink drain opening thoroughly
Roll plumber’s putty into a rope and place it under the drain flange
Insert the drain flange into the sink opening
From below, attach the rubber gasket, friction washer, and locknut
Tighten the locknut until the flange is secure
Wipe away excess putty or sealant
Attach the drain tailpiece to the drain body
Connect the P-trap and other plumbing connections
Tighten all slip nuts by hand, then snug with a wrench
Turn on the water and check for leaks
Tighten any leaking connections if needed