What Is a Coupling Used For in Plumbing?
A coupling is a plumbing fitting used to join two pipes together in a straight line. Its primary function is to extend pipe length or repair a broken section.
What a Coupling Does
1) Standard (Straight) Coupling
Same size on both ends
Example: ¾" × ¾"
2) Reducing Coupling
Steps from larger pipe to smaller pipe
Example: 1" × ½"
3) Slip / Repair Coupling
No internal stop
Slides over pipe to repair a cut-out section
Common Materials
You cut a section of copper pipe to remove a leak. You install a copper coupling to join the two pipe ends back together.
In Plain English
A coupling simply connects two pipes together in a straight line.
A coupling is a plumbing fitting used to join two pipes together in a straight line. Its primary function is to extend pipe length or repair a broken section.
What a Coupling Does
- Connects pipe to pipe
- Creates a straight-through connection
- Can join same-size or different-size pipes (reducing coupling)
1) Standard (Straight) Coupling
Same size on both ends
Example: ¾" × ¾"
2) Reducing Coupling
Steps from larger pipe to smaller pipe
Example: 1" × ½"
3) Slip / Repair Coupling
No internal stop
Slides over pipe to repair a cut-out section
Common Materials
- Copper (sweat or press)
- PVC / CPVC (solvent weld)
- Brass (threaded)
- Black iron / steel (threaded)
- PEX (crimp, clamp, or expansion)
You cut a section of copper pipe to remove a leak. You install a copper coupling to join the two pipe ends back together.
In Plain English
A coupling simply connects two pipes together in a straight line.

