Slide the rubber washer onto the metal tailpiece. Then the compression nut. Hand-tighten it. Then give it a gentle snug with the pliers. Don’t go Hulk mode. Overtightening cracks the plastic. That’s a leaky nightmare. It’s a "finger-tight plus a grunt" kind of tight.
Turn on the water. Watch for drips. If you see a tiny bead of water, tighten a little more. If it sprays like a fountain, you did something wrong. Check your washer. Is it facing the right way? Rubber side goes toward the water. This is the most common mistake. It’s like putting your underwear on backwards. Embarrassing, but fixable.
Why This Is Fun (Yes, Really)
You just solved a puzzle. You connected metal and plastic. That’s like making a cat befriend a goldfish. It shouldn’t work, but it does. You also saved sixty bucks by not calling a plumber. That’s three takeout pizzas. Or a fancy plant. Or a new tool you don’t need.
Plumbing is just adult LEGOs. With water. And consequences. The next time a friend complains about a leaky sink, you can say, "Oh, I just did that. It’s easy." They’ll think you’re a wizard. Let them. You deserve it. Now go wash your hands. Not in that sink. Not yet. It needs ten minutes for the glue to cure. Go use the bathroom sink. That one still works. Probably.