A basin wrench is a tool designed for one purpose only: to remove and tighten the nuts that hold the faucet assembly to the underneath of the sink. A long steel rod with a tee handle at one end and a swiveling, spring-loaded jaw-like device at the other, the basin wrench makes it possible to reach the hard-to-get nuts from the bottom of the faucet assembly. Commonly constructed with a solid steel handle, the basin wrench is also available with a telescoping steel handle, and there are even plastic models intended for one-time use. The design of the basin wrench allows it to work on hex and square nuts alike.
When changing a faucet, there is typically no room under the sink to maneuver and use an adjustable wrench or even pliers to remove the faucet from the sink. By using a basin wrench, the nuts securing the faucet to the sink can be removed almost effortlessly. Once the water supply has been shut off and the supply lines have been removed from the bottom of the faucet with an adjustable wrench, the basin wrench can be used to reach up and under the faucet and remove the attachment nuts. The hardened, serrated teeth on the basin wrench allow it to grip even the most rusty and corroded nuts and turn them.
Once the nuts are removed, the assembly can be lifted up and out of the sink. The faucet can then be easily maintained or replaced at the plumber's discretion. If repairing and replacing an original faucet, it is typically recommended that new fastening nuts be installed on the assembly. If installing a new faucet, it is recommended by many faucet manufacturers that a small amount of anti-seize be applied to the threads of the attaching nut to avoid sticking and promote easy removal in the future.
Tightening the retaining nuts is simply the reverse of removing them. The design of the basin wrench allows the jaws to be swiveled to almost any angle, including reversed or upside-down, to facilitate tightening and removal of the retaining nuts. With the water supply lines reinstalled and the water turned on, the sink can be checked for leaks. By utilizing the basin wrench, the usually time-consuming and difficult task of removing the faucet nuts can be turned into a relatively easy and expedient do-it-yourself home plumbing project.