By following these directions, a leaky faucet can usually be repaired without having to call a plumber and then incur the expense of a plumber's services. Usually the problem can be solved easily by the replacement of a worn out rubber washer, called an O-ring. Over time the washer wears out, which then allows water to pass between it and the valve seat, resulting in a leak.
First you must determine the type of faucet. It is either a compression faucet, which has separate hot and cold water handles, or a non-compression, which has only one lever or knob to control the water flow.
The following instructions cover a compression, two-handle faucet.
First Step: Shut the water at the stop valve, which can be located either below the fixture or at the main shut off valve. Whether the leaking water is warm water or cold water again will indicate which of the handles is causing the leak.
Second Step: Cover the drain. Remove the screw cover on the suspected handle. If there is what is referred to as an 'escutcheon' or decorative top to the faucet handle, this can be removed by gently prying it off with a screwdriver or carefully with the tip of a knife.
Third Step: Remove the packing nut and valve stem. Using an adjustable wrench or using a pair of channel-lock pliers loosen the lock (it must be turned counterclockwise) nut located at the base of stem spindle. By carefully pulling up, lift the stem assembly out of the faucet body. Then turn the large packing nut at the top of the faucet counterclockwise. Then twist out the valve stem, also counterclockwise.
Fourth Step: Using the channel-lock pliers, hold the stem assembly. Remove the retaining screw that holds the old washer in place with a screwdriver. Remove this screw and the old washer. A beveled washer or a flat washer may be required. Taking these parts down to a hardware store will help indicate, by comparing them exactly, what replacements parts are needed.
Fifth Step: Replace washer and brass stem screw. Place washer with the flat side against the base. Put back the retaining screw. By rubbing some petroleum jelly around the threads of the stem will help with future removal of this part. Replace the packing nut and handle. Then hopefully when the faucet is turned on, there is no more leaking. Again if this is a double handle faucet, and it still drips, then the other handle may require a new washer. Or the faucet itself may need to be replaced. If water continues to leak, then the valve seat needs replacing, which may require contacting a plumber.
Sixth Step: If an O-Ring needs to be replaced, remove the lock nut from the stem spindle. With the use of long nose pliers, remove the O-ring. Then replace it with an identical O-ring, ensuring that it is firmly seated in the groove. Again, the use of petroleum jelly can be applied to lubricate it to ensure a good seal and easier future removal if required.
If the leak is coming from a noncompression faucet, then the faucet should be disassembled, and replaced with a new mechanism, which is usually in the form of a 'cartridge.' The best thing to do is to take the entire unit to the hardware store and find an exact replacement, and follow manufacturer's directions when installing the unit.