Below are some images of various plumbing fittings used in residential water distribution systems. Although, only one type of each fitting may be shown, there are many different brands/types of each fitting, manufactured using a variety of materials and joining methods.
Tee's are used to add a branch to a water supply. They may have all openings the same size or be reducing on one or two sides.
90 Degree Elbow
90's are used to make to make a right angle change in the direction of flow.
45 Degree Elbow
45's are usually used in pairs to make either a diagonal offset or they can be rolled to make a 90 degree offset.
Couplings are used to connect lengths of pipe and to make repairs to damaged sections.
Like a coupling, a reducer joins two pieces of different sized pipe. They come in either hub ends (meaning they fit over the pipe) or "fit in" (meaning that one end will fit inside the hub of a fitting).
A bushing is a reducer that fits inside of another fitting.
Drop ear 90/ Wingback 90
These fittings have a mounting support flange attached and are commonly used for shower heads and fixture supply valves.
Although not technically a fitting, nipples (threaded pieces of pipe 6" or less) are commonly available with pre-cut threads.
Caps are typically only used for rough-in's or for renovations. Leaving sections of water supply pipe dead ended should always be avoided.
Water Hammer Arrestor
These devices are used to prevent the sudden shock of fast acting valves which create water hammer. Learn more here: Water Hammer Arrestors
The most common valve used today as they don't restrict flow. They also make it very easy to tell if they are open or closed by the position of the valve handle. If th
e valve is open the handle will be running the same direction as the pipe.
Used as an isolation valve. Not used for throttling water flow.
Used as an isolation valve and is suitable for throttling water flow. Can be visually differentiated from a gate valves by the shape, globe valves always have a pot-bellied appearance.
These valves typically come in a Water Supply kit for a cooling device (fridge, water purifier). They clamp to the side of a pipe and then pierce the pipe wall, when the valve is turned clockwise. They have a high failure rate and should be avoided.
These are fixture isolation valves. They come in 1/2" (threaded, pex or soldered) by usually 3/8" compression for most fixtures.
These valves are used to control the maximum temperature to a fixture or group of fixtures. They have a hot and cold inlet and the outlet can be adjusted to the desired temperature.
Unions are used to connect a pipe where the need may arise for it to be taken apart at a later time (IE: Hot water tank)
A Dielectric Union is used to prevent dissimilar metals from contacting each other, as this will cause corrosion (galvanic action). These are commonly used on the exposed galvanized nipples of hot water tanks.
Adapters are used to change a pipe end to a male or female end. The image to the right shows a male adapter.
A threaded plug is often used to block a valve end or for rough-in's.
Sediment Faucet / Hose Bibb
Used to supply/isolate water lines to device that require a standard 3/4" hose end, such as a washing machine. Learn more here: Hose Bibbs
There are many types of backflow preventers, but the most common residential types are single and dual checks, which are installed to prevent any water from going back into the city supply after it enters your home. Learn more here: Backflow preventers