A faucet is loud for a reason. Faucets squeal and screech not because they like to aggravate their owners. Think of that squealing and screeching faucet like a child crying out for help, because something is wrong–in this case it’s a loose part that needs replacing. When faucets make noises, it is time to tighten or repair the stem.
Squealing and screeching faucets have a loose seat washer inside the stem that vibrates and flaps around wildly as water rushes by. That’s why the sound occurs only when the faucet is on. Normally, replacing the stem, which includes several parts including the washer, solves the problem.
Important parts to fix in order to repair a screeching or squealing faucet are all inside the handle’s stem, which is the valve controlling your water flow.
Fix a squealing or screeching faucet by replacing the stem. Just take off the handle by unscrewing the set screw with a Phillips screwdriver or an Allen wrench and popping the handle off.
Next, use a bath socket wrench also called a stem wrench, to unscrew the stem, which is right under the faucet handle. Remove any stem nuts or any nuts on top of the stem first with a regular wrench.
If the faucet is old, it might be a good idea to replace the seat as well while you are at it. Seats are located inside the handle pipe, and they are difficult to remove, so be prepared for a bigger job. Use a stem wrench and carefully tap it to loosen the seat
Find a replacement seat and stem for your squealing faucet at a plumbing supply store, and make sure it is the right part for your make and model.
Insert the seat in the handle pipe, tighten it with the seat wrench until very tight, and then screw the seat on with the bath socket.
Replace the handle and turn on the water. Test the faucet by turning it on. If there is still a loud noise, turn off the water and remove the handle again. Tighten the seat and stem as needed, or replace the other stem and seat to fix that squealing, screeching faucet.