Outdoor faucets that supply your landscaping and outdoor utility are simpler than the ones indoors because you usually don't need hot water outside. They have to be able to withstand weather conditions without corroding, and they also must be able to withstand occasional abuse. Outdoor faucets don't have the variety of valve mechanisms that indoor faucets do.
Spigots and Hose Bibs
Most homes have spigots or hose bibs installed on the outside walls or somewhere in the yard. The difference between the types is that a hose bib has a threaded spout so you can screw on a garden hose. Both types have a simple compression valve that works by tightening a washer agains the valve opening when you tighten the handle to shut off the water. Spigots and hose bibs are usually made of brass or galvanized steel and may last for many years. When one leaks, you usually can fix it by tightening the retaining screw or by removing the valve and replacing the washer.
If you live in a cold climate, freezing temperatures can turn water to ice in conventional spigots or hose bibs, and damage the valves or break the pipes leading to the faucet. The design of a frost-free faucet prevents this by incorporating a long metal tube that extends inside the house. The valve is placed at the far end of the tube to keep water in the warmer environment of the house when the faucet is off. Frost-free faucets come with tubes of various lengths and can be installed and repaired in exactly the same way as regular compression faucets.
One of the most basic faucet designs incorporates a tight-fitting ball in the valve chamber. The ball has a single hole through which water can pass, and when it is turned perpendicular to the faucet direction, the water is off. Common materials for ball-valve faucets are PVC plastic and brass. They don't give as much control over water flow as compression faucets do, and are suitable when you you want to turn the water completely on or completely off. For this reason, they are often used as shut-off valves in indoor and outdoor plumbing pipes as well as landscaping lines.
Anti-siphoning, or backflow prevention, is a feature found on many outdoor faucets. You can add this feature to any outdoor faucet by screwing an anti-siphon valve to the spout, and many outdoor faucets come with one pre-installed. It is important to have an anti-siphon valve on your outdoor faucet if it is connected to your drinking water. The valve prevents contaminants from being sucked back through the faucet and into your water when you leave the hose out in the garden or you connect a drip system to the faucet. Anti-siphon valves are a requirement on outdoor faucets in some localities.