If you have a ceramic disk faucet, you should be able to fix it yourself since it doesn't have many parts. A disk faucet operates on a cylinder base sitting on two ceramic or plastic disks connected to a single lever or handle. When you turn on the faucet, the disk on top rotates and aligns itself with the holes on the bottom disk. Here are some tips on fixing a leaky disk faucet.
Turn Off the Water
To make this repair you need, pliers, soft nylon brush, dish soap, masking tape, groove joint pliers, a flathead screwdriver, Phillips screwdriver or Allen wrench, and a ceramic disk faucet repair kit that matches the model of your sink. Look for shut off valves under the sink, and turn the lever to the right to shut off the water.
Some valves may need to be lined up perpendicular with the water line to be closed. If you can't find a shut off valve, turn off main water line to the house. Turn on the tap to release water pressure.
Detach the Handle
Keep screws and other small parts on masking tape so they won't fall off the sink. Detach the handle with a Phillips screwdriver, and use the Allen wrench for hex head screw sets. If there's a cap on the handle, pull it off with the flathead screwdriver. Pull the handle from the base, and remove the dome casing from the handle base to expose the disk cartridge.
Remove the Disks
Remove the disk screws if needed, and pull the disk out with pliers. If the disk is stuck, pull it off with groove joint pliers. Check the disk cartridge for damage. If you don't find any cracks or holes, try cleaning the disk, gasket, and seal seats with dish soap and the soft nylon brush to remove residue. Put everything back in place, and test the sink again for leaks again. Any damaged parts or corroded parts that can't be cleaned will need replacing.
Save the old disk cartridge to use as a guide for buying a replacement. Set the new disk back in place pointing the gasket down, reinsert the disk screws, and place the dome casing on the disk cartridge. Reattach the handle by holding it up, fasten on the handles crews with the Allen wrench or Phillips screwdriver, and replace the cap.
Turn the water back on to test for leaks. If your repair doesn't stop the leak, you will need a plumber to find the problem.