Step 5 · Clean or Replace Faucet Cartridge
If the supply lines have good pressure, the clog is in the faucet's cartridge(s). For a double-handle faucet, you'll need to remove each handle. This usually involves prying off a decorative cap and removing a screw with a screwdriver. Once the handle is off, use pliers or an adjustable wrench to unscrew the retaining nut holding the cartridge (or stem) in place. Pull the cartridge straight out. You may need to wiggle it gently. Inspect the small inlet ports on the cartridge for debris. Use a small pick or pin to carefully clean them out. You can also flush the cartridge under running water. Apply a thin layer of plumber's grease to the O-rings before reinserting it. If the cartridge is visibly damaged or heavily calcified, it's best to take it to a hardware store to find an exact replacement.