Clean out all of the supplies stored under the sink. Turn off the water supply to the sink and open the faucet to relieve the water pressure. If your sink is not equipped with shut-off valves called stop valves under the sink, turn off the water at the main shut-off valve. This valve is usually located in the basement or utility area.
Step 1 : Remove the old faucet
Begin by removing the old faucet. Loosen the compression nuts at the lower end of the water supply tubes called riser tubes that lead from the wall up to the old faucet. Use a basin wrench to loosen the nuts that secure the riser tubes to the faucet. The wrench is designed to reach up from underneath the sink and grab these hard-to-reach nuts. Once the nuts are loose at both ends of the riser tubes you may have to wiggle them a bit to get them loose.
Use the basin wrench to remove the locknuts that hold the faucet to the countertop. If they are rusted, apply penetrating oil to them and let stand for 15 or 20 minutes before you try again.
A faucet with a pullout spout connected to the water supply with a hose usually has a center-mounting nut. The spout hose loops down below the countertop. You have to remove the hose from the valve body before you can completely lift the faucet off the counter. First, remove the riser tubes and mounting bolts, and then pull the faucet partially out of the sink. Then remove the hose and the faucet will lift completely out of the countertop.
Step 2 : Scrub sink
With the old faucet completely out of the sink, thoroughly clean the surface around the mounting holes. Scrape any hard plumbers putty off the sink with a putty knife. Then, wash this area. You may need to use a scouring pad to remove all residue.
Step 3 : Insert the new faucet into sink
Place a bead of plumber's putty around the base of the faucet. Position the faucet spout to the front, over the sink, then lower the pre-assembled faucet supply lines and spring-loaded toggle mechanism through the sink holes.
Step 4 : Tighten the toggle bolts
Lift the escutcheon plate and rotate it to expose the toggle bolt heads. Use a screwdriver to tighten these bolts. As you tighten the bolts, push the faucet down on the plumbers putty. Tighten the bolts until the faucet is fully seated and is level on the sink.
Step 5 : Lock escutcheon in place
Lift the escutcheon and replace it over the toggle bolts to hide the mounting plate. Install the small snap ring on the back of the faucet between the escutcheon plate and the spigot body first, then install the larger snap ring on the front of the faucet.
Step 6 : Connect the water supply lines
Underneath the sink, connect the preinstalled riser tubes to the stop valves. Thread the compression nuts on the valve and tighten by hand. Then finish the process with a wrench.
Turn on the water supplies and check for leaks. Before you open the new faucet, remove the aerator at the end of the spigot. Then, turn the water on and rotate hot through cold to flush out the lines of the faucet. Turn the faucet off and replace the aerator.
Illustrations courtesy of Sterling®