Plumbing Fittings: Types, Connections, and When to Use Each
Plumbing fittings are the connectors that join, turn, split, resize, or cap off pipe. The everyday set is small: elbows change direction, tees split a line, couplings and unions join two pipes, reducers change size, and caps close an end. How each one attaches (threaded, soldered, glued, compression, or push-fit) depends on the pipe material and whether you need to take the joint apart later.
What are the main types of plumbing fittings?
The main types of plumbing fittings are elbows, tees, wyes, couplings, unions, nipples, reducers, bushings, caps, plugs, and adapters. Each does one job: change direction, branch a line, join two pipes, step the size up or down, close an end, or switch the connection method. The table below maps each fitting to what it does and when to reach for it.
| Fitting | What it does | When to use it |
|---|---|---|
| Elbow (90 or 45 degree) | Turns the run to a new direction | Routing around a corner or up a wall; 45s for gentler drain turns |
| Tee | Splits one line into two, or merges two into one | Branching a supply or drain off a main run |
| Wye (Y) | Branches a drain at a sweeping 45 degrees | DWV drain lines where flow needs to stay smooth |
| Cross | Four openings from one point | Rare in homes; fire sprinkler and some commercial grids |
| Coupling | Joins two pipe ends in a straight line, permanently | Extending a run or splicing a cut section, often inside walls |
| Union | Joins two pipes but unscrews to separate | Where you may disconnect later (water heaters, pumps, gas) |
| Nipple | Short threaded pipe stub between two female fittings | Close spacing between threaded valves or fittings |
| Reducer | Connects two different pipe diameters in line | Stepping a line down or up in size |
| Bushing | Threads into a fitting to shrink its opening | A tight size change where a reducer will not fit |
| Cap | Closes a pipe end from the outside | Sealing a stub-out or an abandoned line |
| Plug | Closes a fitting from the inside | Sealing a threaded port, cleanout, or test opening |
| Adapter | Changes the joining method (sweat to thread, etc.) | Transitioning between materials or connection types |
Direction and branch fittings
Elbows, tees, wyes, and crosses steer and split the flow. An elbow bends the run, usually 90 or 45 degrees. A tee makes a 90-degree branch, while a wye branches at a gentler 45 degrees so drain water keeps moving. Crosses show up mainly in sprinkler and commercial work, not in most homes.
Joining fittings
Couplings, unions, and nipples connect two pieces of pipe in a straight line. A coupling is a permanent join once glued, soldered, or crimped. A union adds a central nut so the joint unscrews for service. A nipple is a short threaded stub that links two female fittings where space is tight.
Sizing and closing fittings
Reducers and bushings change pipe size, and caps and plugs close an opening. A reducer connects a larger pipe to a smaller one in line, while a bushing threads inside a fitting to shrink its port. A cap covers a pipe end from outside; a plug seals a fitting from inside, often at a cleanout or test port.
How do plumbing fittings connect to pipe?
Plumbing fittings attach to pipe one of a few ways: threaded, sweat (soldered), solvent weld (glued), compression, push-fit, or a PEX ring method. The right one depends on the pipe material and whether the joint must come apart later. The table pairs each connection method with its best material and whether you can service it without cutting.
| Connection method | How it joins | Best material | Serviceable? |
|---|---|---|---|
| Threaded (NPT) | Tapered male and female threads sealed with tape or dope | Galvanized steel, brass, black iron (gas) | Yes, unscrews |
| Sweat (soldered) | Solder melted into the joint with a torch and flux | Copper, brass | No, cut it out |
| Solvent weld (glue) | Chemical cement fuses fitting and pipe | PVC, CPVC, ABS | No, cut it out |
| Compression | A nut squeezes a ferrule (ring) onto the pipe | Copper, supply tubing, angle stops | Yes, loosen the nut |
| Push-fit (SharkBite) | Internal teeth and an O-ring grip the pipe | Copper, PEX, CPVC | Yes, with a release clip |
| PEX crimp / cinch / expansion | A ring or expanded pipe locks the fitting | PEX | No for crimp and cinch; partly for expansion |
Two details trip people up. NPT threads are tapered, so they wedge tight as you turn and need PTFE tape or pipe dope to seal. Sweat means soldered, a permanent copper joint, not a slip-on part. Compression and push-fit joints stay serviceable, which is why they suit fixtures and shutoffs you may work on again.
Which fitting connection should you use?
Choose the connection by the pipe material and how accessible the joint is. Permanent runs behind walls favor soldered or glued joints; anything you may service later favors compression, unions, or push-fit. Codes on concealed push-fit joints vary by area, so confirm local rules before you hide one in a wall. Use this order as a guide.
- Copper you plan to leave in a wall: sweat (solder) it for a low-profile permanent joint.
- PVC, CPVC, or ABS supply and drain: solvent weld with the cement matched to that material.
- A fixture, valve, or supply line you may service: use a compression fitting or a union.
- A fast repair or a spot you cannot heat safely: push-fit like SharkBite, where local code allows it.
- PEX runs: crimp, cinch, or expansion, depending on your tool and PEX type.
- Threaded steel, brass, or gas pipe: NPT threads sealed with PTFE tape or pipe dope.
What is the difference between a coupling and a union?
A coupling and a union both join two pipes in a straight line, but a union can be taken apart. A coupling is permanent: once it is glued, soldered, or crimped, separating the pipes means cutting it out. A union has a large central nut that unscrews, so you can disconnect equipment like a water heater or pump without cutting.
That difference decides where each belongs. Use couplings to extend or splice a run you will not touch again, often buried in a wall or ceiling. Use unions at any point you expect to service, since they let you break the line and rejoin it many times. The same logic applies to plumbing valve types that isolate sections of the system.
Do plumbing fittings have to match the pipe material?
Fittings are made for a specific material and connection method, so the base fitting should match the pipe: copper fittings for copper, PVC for PVC, PEX for PEX. Where two materials meet, an adapter or transition fitting bridges them, and a dielectric union separates dissimilar metals to slow corrosion. Match the fitting to the pipe, then transition on purpose.
Which pipe you have drives which fittings you buy. For an overview of every supply and drain material, see our guide to the types of plumbing pipes. If you are working in flexible tubing, our walkthrough on how to plumb with PEX covers crimp, cinch, and expansion fittings, and copper plumbing basics explains sweat and press joints for rigid copper.
Frequently asked questions
What are the different types of plumbing fittings?
The common residential plumbing fittings are elbows (change direction), tees and wyes (split or merge a line), couplings and unions (join two pipes), nipples (short threaded stubs), reducers and bushings (change size), caps and plugs (close an end), and adapters (change the joining method). Most home jobs use only a handful of these.
What is the difference between a coupling and a union?
Both join two pipes end to end. A coupling is permanent: it is glued, soldered, or crimped, so separating the pipes later means cutting it out. A union has a central nut that unscrews, letting you disconnect and reconnect without cutting. Use unions near equipment you may service, such as a water heater, pump, or gas appliance.
Do you have to solder plumbing fittings?
No. Soldering (sweating) applies only to copper and brass. PVC, CPVC, and ABS join with solvent cement (glue), threaded metal pipe uses PTFE tape or pipe dope, and compression or push-fit connectors need no heat or glue at all. Push-fit fittings like SharkBite grip copper, PEX, and CPVC with hand pressure.
What is the difference between a reducer and a bushing?
A reducer is a fitting whose two ends are different sizes, connecting a larger pipe to a smaller one in line. A bushing is a smaller insert that threads into an existing fitting to shrink its opening. Use a reducer to change size in a run, and a bushing when you need the size change inside a fitting already in place.
Are push-fit fittings like SharkBite reliable?
Push-fit fittings such as SharkBite are reliable on clean, deburred, correctly cut pipe, and their makers rate many for behind-wall use. Local code still varies on concealed installs, so check your jurisdiction. Many plumbers use them for quick repairs and accessible spots, and rely on soldered or crimped joints for long permanent runs.
What are the 3 main types of pipe fittings?
There is no official three, but the fittings you reach for most are elbows to change direction, couplings to join pipe, and tees to branch a line. Add unions for serviceable connections and adapters to switch between materials, and you can handle the large majority of residential plumbing tasks.
Last reviewed: September 2026.