Today, most faucets can be categorized as being "washerless" (port-type faucets) or of the "compression" (washer) type.
Washerless faucets can be either single handle or the two-handle type. In washerless faucets, the control of the water flow is done by a replaceable cartridge or arrangement of seals that allow water flow, then the holes or ports are lined up in the proper configurations. Giving the handle an extra hard twist to stop water flow will be ineffective. This type of faucet does not use compression strength to stop water flow.
A washerless faucet does not mean it will never leak, but rather because of the way it is designed, the parts will last much longer, as their design minimizes friction and wear.
When repairing this type of faucet or requesting service on one, it is vital that you know the brand name, or have a sample of the part you require, as there are hundreds of faucet cartridges and parts kits on the market today.
Your licensed union plumber will carry an extensive assortment of faucet parts in his or her service truck, but it is impossible to carry absolutely every part. So it can be very helpful if the brand of faucet is known in advance.
In a compression-type faucet, you will find the conventional setup—a faucet washer on the end of the stem. Replacing the washer usually will correct a dripping faucet.
However, when removing the stem, always check the seat inside the faucet body—the brass ring that the washer grinds against. The faucet seat can be worn or grooved, making the washer replacement ineffective within days. The washer and seat are the two parts of a compression-type faucet that receive the greatest amount of wear. It is not difficult to replace a washer. First, shut off the water supply. Usually, the shut-off valve is under the sink. If there is none, shut off the branch-line valve in the basement or the main valve where the water supply enters the house.
Pad a smooth jawed wrench with a cloth, and unscrew the large packing nut. Turn out the faucet stem. Then remove the screw from the bottom of the stem with a screwdriver that fits the screw slot closely, and pry out the worn washer. If the screw is tight or stubborn, tap its head lightly or apply penetrating oil (WD-40).
Next, clean out the washer seat or compartment. When this is done, insert the new washer of the correct size and composition for hot or cold water.
Some of the newer, soft neoprene washers are for both hot and cold water and have a long life. The washer should fit snugly without having to be forced into position. After inserting, replace the screw and tighten.
It is usually just as expensive to renew a seat, as it is to buy a new faucet, unless it has been made with a renewable seat. Check with your plumber about a badly worn faucet.
With cloth over finger, clean the valve seat inside the faucet. The edge should be smooth and free from deep nicks. If you find it badly worn, you will probably need to replace the seat or have the entire faucet replaced by the plumber. Otherwise, it will leak again.
Next, replace the faucet stem and turn it in. Tighten the packing nut. Be careful not to tighten the nut more than necessary to stop seepage around the faucet stem.
A faucet leaking 60 drops a minute will waste 2,299 gallons of water every year. Repair a leaky faucet at once. You may be paying twice for the leaking water—once for the water going through the meter, and again on your sewer bill, if it is based on water usage.