Test that you cut the water supply by turning on the faucet—no water should come out. If it does, turn the valves more and check again.
If you can’t fit a bucket in the space under the P-trap, just lay an old towel underneath it to absorb the water that comes out.
Some metal sinks are held in place with metal clips that you need to unclip in order to remove the sink. Be careful that you don’t damage the vanity countertop when you slice through the caulk around the sink’s bowl.
Check that you have a drain and tailpiece for the sink. The tailpiece is the straight pipe that connects the bottom of the drain to the P-trap. Then, check that the faucet’s supply lines line up with the water supply valves that are underneath the sink. If they’re really long and taking up a lot of space under the sink, you can use a utility knife to cut them to size. If you don’t have a template of the mounting opening, simply set the new sink in place and see if the openings line up with the existing plumbing.
If you see small gaps between the sink and the countertop, fill them in with silicone caulk.
Don’t worry if your sink didn’t come with clips. Most common sinks, like ceramic or porcelain, use caulk to hold the sink in place.
If your new faucet didn’t come with a gasket, spread silicone caulk or plumber’s putty around the bottom edge of the new faucet before you place it in the sink. This forms a seal. If you’re using the faucet from the old sink, remove it by loosening the big nut under the sink and disconnecting the supply lines from the hot- and cold-water valves. It’s fine to install the faucet before you install the sink if it’s easier for working with your space. Just make sure the space for the faucet matches the location of the sink, using the template to measure before you install anything.
If excess caulk squeezes out of the sides, take a cloth and wipe it away before it dries.
If the tailpiece is too long to fit snugly with the P-trap, use a pipe cutter to make the tailpiece shorter.
In general, manufacturers direct you to slide the nut to trap the ball in the tailpiece. Tighten it so there’s no wiggling, but don’t make it so tight that you can’t raise or lower the pop-up.
It’s also a good idea to check the gasket that goes under the tailpiece. Try tightening the nut down more or use a different washer or silicone caulk.
