Faucets are valves for controlling water. There are four basic faucet designs: compression, ball-type, cartridge and disk. When any faucet starts to drip, the problem is usually a worn seal or component. Fortunately, these parts are readily available, and replacing them is simple. You can usually identify a faucet by its body configuration or manufacturer.
Compression faucets usually have two handles, one for hot, the other for cold water. They have washers that wear quickly and often require replacement. Ball-type, cartridge and disk faucets are washerless; they usually require less maintenance. Ball-type faucets have a single handle mounted on a rounded cap. Delta or Peerless are leading ball-type faucet manufacturers.Cartridge faucets have cylindrical bodies and are available in single-handle or double-handle models. If your faucet was made by Aqualine, Moen, Price Pfister or Valley, it is probably a cartridge faucet.
Disk faucets have cylindrical bodies and a single handle. American Standard and Reliant are popular disk-faucet brands.
Before starting any repair, turn off the water by closing the shutoff valves under the sink. Open the faucet so that the water drains out. It's a good idea to cover the drain in case you drop any small parts.
Next, remove the faucet handle. Some handles are mounted on the body with a setscrew. Loosen it with an Allen wrench, then lift off the handle. Other handles are held in place with a screw through the top of the handle. The screw may be concealed under a decorative medallion or plastic cap. Pry the cap off with a screwdriver then remove the screw.
Ball-type faucets control water flow with a hollow ball. Moving the handle rotates the ball over water supply ports and allows water to flow. The ports are fitted with neoprene valve seats that hug the ball and keep water from leaking. Positioned on top of the ball are a cam washer and a cam. The cam washer creates a water-tight seal above the ball; the cam helps to align the ball with the ports. The entire assembly is held in place by the rounded cap.
If your ball-type faucet leaks, try tightening the cap with a pair of channel-type pliers. Tape the plier jaws with masking tape so they will not mar the cap finish. If the faucet still drips, the valve seats or the cam washer are probably worn and should be replaced. In rare instances, the ball may be damaged and need to be replaced.
Manufacturers offer different repair kits that contain the parts needed to fix the faucet. A complete kit should include a new cam, cam washer, two valve seats, seat springs and an instruction sheet showing the correct replacement procedures. Depending upon the faucet, the kit may also include a small tool to help remove an adjusting ring in the cap (not present in all faucets).
Remove the rounded cap by unscrewing it with the channel pliers. Lift off the cam and the cam washer, then lift out the rotating ball. Examine the ball carefully for signs of excessive wear. If the ball is damaged or worn, replace it. Replacement balls are available in plastic or metal. The metal ones are more expensive, but are more durable.
Remove the neoprene valve seats and springs by prying them loose with a screwdriver. Install the new springs and valve seats; replace the ball, the cam washer and cam. Screw the rounded cap on the faucet, then replace the handle.