Overview
Total time: 15 minutes
Skill level: Elementary
Estimated cost: $2
Faucets with compression washers or compression faucets are common in old houses. The compression faucet uses a washer, which is compressed by tightening the faucet handle to cut off the flow of water. Over time, the washing machine wears out, so the water never turns off completely. Replacing gaskets can usually stop leaks and is usually much cheaper than replacing filter elements on more modern faucets.
Plastic Faucet Suppliers will tell you what you need
Equipment/tools
Grooved pliers
Small slotted screwdriver
Phillips screwdriver
Compression faucet handle puller (as required)
material
Replace the stem gasket
Replace O-ring (optional)
Waterproof plumber grease
Instructions
Shut off the water supply
Look for a small shut-off valve (usually with a football-shaped handle) on the water line below the sink. Turn the handle clockwise to close the valve. If there is no shut-off valve under the sink, please turn off the water supply to the house through the main shut-off valve or water meter in your home. After turning off the water source, open the faucet fully to release any pressure and residual water in the pipe.

Remove the faucet handle
The handle body is connected to the valve stem assembly of the faucet through a screw hidden under the decorative cap. The lid on the old faucet is usually metal and screwed into the handle. To access the screw fixed to the handle, clamp the cover with pliers and unscrew it. If the cover is plastic, use a small flat-blade screwdriver to pry open the cover.

The metal cover of some faucets can also be pried off. What's the best way to say it? If the metal cover has jagged edges, it may be a screwed-off cover. If the lid is thin or has a smooth edge, it is likely to be pried off.

Use a Phillips screwdriver to remove the screw that secures the handle to the valve stem. Pull the handle straight up to remove it from the valve stem. If the handle is stuck, you may need to use a compression faucet handle puller to remove it.

Remove the valve stem assembly cover (as required)
After removing the handle, you may find a lid on the stem assembly (especially single-handle faucets, which are commonly found on bathtubs and some sink faucets). Use pliers to unscrew the knurled knob that fixes the valve stem assembly cover, and remove the valve stem assembly cover.

Disassemble the stem assembly
Look for the hexagonal nut part of the valve stem assembly, which is usually located where the assembly and the main body of the faucet meet. Use pliers or adjustable wrench to clamp the nut and turn it counterclockwise to loosen the valve stem assembly. Unscrew the valve stem assembly completely and pull it out of the faucet body.

Compression stem assembly diagram
Remove the stem gasket
Locate the old gasket at the bottom of the valve assembly, in the seat. It will be screwed in place and may be worn or deformed. Remove the brass screw fixed on the washer. Insert a small flat-blade screwdriver into the hole of the gasket and pry it out of the valve seat. Clean any deposits or residual rubber on the end of the gasket bracket so that the new gasket is cleanly installed in the seat.

Looking for alternatives to old washing machines
You may need to buy various gaskets, usually sold as "faucet repair kits." If necessary, you can also replace the rubber O-ring around the valve stem assembly.

Push the replacement washer into the valve seat and fix the washer with a brass screw. If applicable, replace the O-ring. Apply a thin layer of waterproof plumber grease to the outside of the O-ring (old or new).

Reassemble the faucet
Screw the valve stem assembly into the faucet body and tighten it with pliers. Reinstall the handle and cover. Turn on the water supply and check if the tap is leaking.