Step 6 · Final Tightening and Test for Leaks

This is the step people usually slow down on. Go finger-tight first, then a quarter turn. No rush — replay the clip whenever it helps.

After hand-tightening, use the channel-lock pliers to give each slip nut a final quarter-turn. This provides the necessary compression for a watertight seal without risking damage. Do not apply excessive force. Place a dry paper towel on the cabinet floor directly under the P-trap; this will make even the smallest leak immediately visible. Turn the sink faucet on and let cool water run for at least a minute. Watch both slip nut connections closely for any drips. Then, stop the sink drain, fill the basin about halfway, and release the stopper to test the connections under the pressure of a large volume of water. If a leak appears, try tightening the nut slightly more. If it persists, disassemble, check washer alignment, and re-tighten.