Turn off water supply if needed and clear the cabinet under the sink
Gather parts: sink strainer, tailpiece, P-trap, trap arm, drain pipe fittings, slip nuts, washers, plumber’s putty or silicone, pipe cutter, wrench
Install the sink strainer in the sink drain opening
Apply plumber’s putty or silicone under the strainer flange
Tighten the strainer assembly from below
Attach the tailpiece to the sink strainer
Connect the tailpiece to the P-trap inlet
Install the P-trap so the trap bend is directly below the sink drain
Connect the trap arm from the P-trap outlet to the wall drain stub-out
Keep the trap arm sloped slightly downward toward the wall drain
Align all fittings before tightening slip nuts
Hand-tighten slip nuts, then snug with a wrench if needed
Make sure the P-trap is not too high or too low
Ensure the trap arm is not pushed too far into the wall drain
Install a dishwasher branch tailpiece if connecting a dishwasher drain
Add an air gap or high loop for dishwasher drain connection if required by code
Check that the venting is adequate and the drain is not blocked
Run water and inspect all joints for leaks
Tighten or reseal any leaking connections
Test both hot and cold water flow through the drain
Dispose of wastewater properly and clean up the work area