A plastic basin nut wrench is a device that removes the plastic nuts that attach a faucet to a sink basin. Because the nuts are located under the sink near the plumbing lines, they are difficult to access. Traditional wrenches aren't effective at removing these nuts because there isn't enough room to turn the wrench. A plastic basin nut wrench has a compact design with a self-adjusting gripper that clamps down on the nut.
Kneel on the floor to access the bottom of the sink. You may need to open the cabinet door if the sink is installed in a cabinet.
Locate the two silver water shutoff valves that are positioned on the wall under the sink. Turn each valve clockwise until it will no longer turn to shut off the hot and cold water supply.
Unscrew the metal nuts at the top of each water shutoff valve by turning them counterclockwise with a regular wrench. Removing these nuts detaches the hot and cold water lines.
Look at the underside of the sink where the faucet is attached to determine what type of nut it is attached with. You will see a traditional nut or a tabbed nut. Tabbed nuts have small tab projections on their outer edges.
Grip the handle of the plastic basin nut wrench, and insert it upward onto one of the nuts until it fits securely in place. If you have a traditional nut, the wrench should fit over the entire nut easily. If you have a tabbed nut, turn the wrench slightly until the notches on the wrench slide over the tabs on the outer edges of the nut.
Twist the handle of the plastic basin nut wrench counterclockwise until the nut starts to move. If the nut is on tightly, you may need to use both hands to turn the wrench.
Continue twisting the wrench counterclockwise until the nut is completely removed. Repeat the process to remove the nut on the other side of the faucet.