Most pop-up drains come with a rubber gasket that creates a seal between the drain and the sink. You may need to use plumbers putty if your pop-up drain does not have a rubber gasket, or if the gasket is not creating a tight seal. To install a pop-up drain with plumbers putty:
1. Apply plumbers putty to the underside of the drain flange.
2. Set the drain flange into place on the sink and press down firmly to create a seal.
3. Attach the popup assembly to the top of the drain flange.
4. Turn on the water supply and test for leaks by running water into the sink basin.