How to Install a Bathroom Sink Drain

Drainage is the unsung hero of the bathroom. When it works, you never think about it; when it leaks, it ruins your cabinetry and floor in short order. Installing a new sink drain seems daunting because of the cramped space inside a vanity, but it is a straightforward mechanical process that relies more on a steady hand and proper sealing than on specialized plumbing talent. Done well, the flange sits flush against the sink basin, the rubber gaskets create a watertight seal, and the overflow holes align perfectly with the sink's design. Focus on even pressure when tightening the components from beneath the basin, and you will avoid the common pitfalls of warped gaskets or cross-threaded nuts that lead to slow, persistent drips.

  1. Seal the Flange First. Roll a marble-sized piece of plumber's putty into a thin 'snake' and wrap it around the underside of the drain flange. This putty acts as the primary seal between the metal drain piece and the sink basin.
  2. Center the Drain Body. Lower the drain body through the sink hole from above, ensuring it sits centered. If your sink has an overflow, verify that the holes in the drain body are facing the overflow channel in the sink.
  3. Position the Rubber Gasket. From underneath the sink, slide the large rubber gasket onto the drain pipe until it sits flush against the bottom of the sink bowl. Ensure the tapered side of the rubber gasket points upward toward the sink.
  4. Tighten With Restraint. Thread the metal locknut onto the drain pipe and tighten it by hand until it is snug against the gasket. Once hand-tight, give it an extra quarter-turn with a basin wrench to ensure a firm seal.
  5. Attach the Tailpiece. Attach the drain tailpiece to the bottom of the drain assembly using the provided plastic washer and slip nut. Hand-tighten the slip nut securely to prevent leaks at the connection point.
  6. Verify No Leaks. Fill the sink basin with water and watch the underside of the drain while the water drains. If moisture appears, tighten the locknut slightly or remove and reseat the putty.