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Water flow in a compression faucet (a common residential faucet) is regulated by turning a lever, T or four-ball handle attached to a threaded spindle. When the spindle is turned down, the washer or disk attached to its lower end is pressed tightly against a smoothly finished ring or ground seat, which surrounds the flow opening to shut off the water flow.

If the washer and seat do not make a firm contact at all points, water will leak; this usually happens when the washer becomes worn.

Most bath, lavatory and kitchen-sink faucets are made with renewable seats which are replaceable when they become worn. Seats in faucets that are not removable may be reground with reseating tools.


A hard rubber- or composition-ball stopper (the Fuller ball) is fastened by a small nut or screw to a shaft with an eccentric end. To replace a Fuller ball, the faucet must be unscrewed and separated from the supply source. The nut or screw should be removed with pliers or a screwdriver, the ball removed and replaced.


ground-key faucet has a tapered cylindrical brass plunger or plug that fits snugly into a sleeve bored vertically through the body of the faucet. The plunger, which is rotated by a handle, has a hole or slot bored horizontally through the body of the faucet. If the slot enlarges and a leak develops, the horizontal opening in the body of the faucet needs to be polished.

The plunger or its sleeve may become grooved or worn by sand or grit particles rubbing against the metal, allowing water to leak through. This requires polishing the rubbing surfaces. The nut or screw at the bottom can come loose, permitting the plunger to move out of its proper position.


Combination faucets mix hot and cold water in a single arm.

Bath and shower faucets can be built into the wall or flush mounted on the wall above the bathtub. They come in different patterns.

In three-valve bath and shower faucets two valves control water and a third diverts water either through the spout or to the showerhead.

Two-valve tub and shower faucets have an automatic device on the spout that, when lifted, diverts water to the showerhead.

Two-valve tub fillers and shower fittings either fill the tub or control water in the shower, not the bath, as do the tub and shower faucets.

Lavatory faucets are also available in several different patterns. A ledge-mounted faucet is mounted on the lavatory or countertop in a horizontal position. Standard faucets are made with 4″ centers; other faucets are made with adjustable center measurements up to 12″.

Another type is called shelf-back faucet and is mounted vertically on the lavatory. Center measurements on these faucets vary with the manufacturer.

Kitchen sink faucets come in a great variety of patterns. Concealed faucets are mounted underneath the sink; only handle flanges and spout are visible. Exposed faucets are mounted on top of the sink, with or without sprays.

mixing faucet, known generally as single lever, is produced by a number of manufacturers as swing-spout kitchen faucets, lavatory faucets and bath faucets. They ordinarily operate by pushing the upright lever straight backward for a 50-50 opening of hot and cold water, back and to the right for cold, and back and to the left for hot water.

They have the advantage of being quick opening and closing, and nearly all have complete repair kits.

Another kitchen-sink faucet is a wall-mounted faucet, which is connected to pipes coming through the wall above the sink. The most common size in kitchen sink faucets is 8″ center, but 6″ and 4″ are also available.

Laundry faucets mount either on laundry tubs or on the wall above the tub. Most fiberglass tubs require a ledge faucet with 4″ centers. Laundry faucets are furnished with a standard 3/4″ hose-thread outlet on the spout.

Automatic mixing valves maintain water temperature, automatically correcting changes caused by turning on other faucets. Thermostatic safety valves protect against sudden bursts of hot or cold water and should be recommended for showers.


Washerless faucets reduce leakage problems that result from worn washers. They are relatively easy to repair if the water-control mechanism is housed in a replaceable cartridge.

Usually a washerless faucet uses a rubber diaphragm or two metal, plastic or ceramic discs with holes that align to let the water flow or close to shut off the water flow. Ceramic plates are more difficult to damage than rubber seats, but hard water can sometimes cause problems with the ceramic cartridges, such as squeaking or sticking. Single-handle faucets that use stainless steel ball design have just one moving part and are a durable alternative.


Located on the outside wall of the house, frost-proof sill cocks are made of heavy red brass and look and work like any ordinary faucet. However, water-flow valves are located inside the building where it’s warm.

When properly installed, frost- proof faucets automatically eliminate the need for one or more inside shutoff valves.

The anti-siphon frost-proof sill cock employs integral back-siphon and back-flow devices. These serve to prevent potential back siphonage which, if unchecked, could compromise the safe potable-water supply to the home. Hose-attached garden sprays and other pressurized canisters can potentially link a cross connection if a pressure charge occurs when the frost-proof is in the open position.

The anti-siphon frost-proof allows for outside spigot usage in freezing climates. The closing member (seat washer) is inside the heated building.

Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.