Plumbing is the system of pipes, valves, fixtures, and related components used to bring fresh water into a building and remove waste and sewage. A properly designed and maintained plumbing system is essential for health, safety, and comfort in residential, commercial, and industrial spaces. Plumbing work includes installing new piping and fixtures, troubleshooting and repairing leaks or blockages, and maintaining the system so it operates safely and efficiently. For a general introduction to the topic, see Plumbing.
Plumbing systems can be made from a variety of materials—including copper, PVC, PEX, and galvanized steel—and their design is governed by local building codes, the building’s intended use, and the available water supply. For an overview of common plumbing materials, consult resources from manufacturers and standards organizations or industry references such as Plumbing 101 for Beginners.
Common acronyms used in plumbing
What does DWV mean in plumbing?
DWV stands for Drain, Waste, and Vent. A DWV system carries wastewater and sewage away from fixtures (sinks, toilets, showers) to the sewer or septic system and provides venting to equalize pressure and prevent traps from being siphoned. Typical DWV piping materials include PVC and ABS, though older systems often use cast iron. Proper sizing, slope, and venting are critical to prevent clogs, odors, and sewer backups.
What does FIP mean in plumbing?
FIP stands for Female Iron Pipe (sometimes also written FPT—Female Pipe Thread). A FIP fitting has internal (female) threads and is designed to receive a male-threaded (MIP or MPT) pipe or fitting. These fittings are commonly made from brass, bronze, or steel and are used for water supply lines, valves, and other threaded connections. Always match thread types and sizes when assembling threaded connections and use appropriate sealing methods (e.g., thread sealant or PTFE tape) per code and manufacturer instructions.
What does IPS mean in plumbing?
IPS stands for Iron Pipe Size. It is a sizing standard that refers to the nominal size and thread form used on many pipes and fittings. IPS describes outside diameters and thread standards that facilitate compatibility among fittings and pipes. IPS-based components are commonly used for water supply and other pressurized systems; ensure fittings and pipes labeled IPS are compatible before connecting.
What does NPT mean in plumbing?
NPT stands for National Pipe Thread. It is a U.S./Canadian standard for tapered pipe threads used to form pressure-tight seals. Because NPT threads are tapered, threading a male NPT into a female NPT compresses the threads and helps create a seal—often supplemented with thread sealant or PTFE tape. NPT is the standard for many plumbing, hydraulic, and pneumatic fittings; see National Pipe Thread (NPT) for details on thread geometry and use.
What does CTS mean in plumbing?
CTS stands for Copper Tube Size. It is a sizing standard used for copper tubing that specifies the outside diameter (OD) of the tube. CTS pipes are commonly used for potable water and heating systems and are available in various wall thicknesses to meet pressure and temperature requirements. For more on copper tubing and fittings, see Copper pipe.
What does MIP mean in plumbing?
MIP stands for Male Iron Pipe (also referred to as MPT—Male Pipe Thread). A MIP fitting has external threads designed to screw into a compatible female-threaded fitting (FIP/FPT). MIP/MPT fittings are used widely across plumbing systems for connections to valves, water heaters, and threaded adapters.
What does ABS mean in plumbing?
ABS stands for Acrylonitrile Butadiene Styrene, a thermoplastic commonly used for drain and vent piping. ABS pipe is lightweight, impact-resistant, and chemically stable for many wastewater applications. It is typically joined by solvent welding or mechanical couplings. For material properties and common uses, see Acrylonitrile butadiene styrene (ABS).
What does FPT mean in plumbing?
FPT means Female Pipe Thread. An FPT fitting has internal threads to accept a male-threaded pipe or fitting (MPT/MIP). FPT fittings are available in brass, steel, plastic, and other materials and are used throughout plumbing systems. Ensure thread standards (e.g., NPT) match on both male and female components for a leak-free connection.
What does MPT mean in plumbing?
MPT stands for Male Pipe Thread, synonymous with MIP in many contexts. It refers to a fitting or pipe end with external threads designed to mate with a female threaded fitting. The thread standard (tapered or straight) must be compatible with the mating part.
What does FHT mean in plumbing?
FHT stands for Female Hose Thread. This refers to the internal threads on fittings that accept garden hoses or other flexible hose fittings, commonly used for outdoor faucets, washing machine connections, and quick-connect hose applications. Hose thread standards differ from pipe thread standards, so don’t mix them without the appropriate adapter.
What does FNPT mean in plumbing?
FNPT stands for Female National Pipe Taper. It is the female version of NPT (tapered) threads and is designed to accept a male NPT tapered thread to create a pressure-tight seal. FNPT is commonly used on fittings, valves, and equipment connections where a tapered thread seal is required.
What does OD mean in plumbing?
OD stands for Outside Diameter, the measurement across the widest external part of a pipe or tube. OD is a critical dimension when selecting fittings, clamps, and connections—especially for copper (CTS), PEX, and other tubing where nominal size and OD can differ. Be sure to check whether product specifications reference nominal pipe size (NPS), inner diameter (ID), or OD when designing or repairing a system.
Good practice notes:
- Always use the correct thread, size, and material for the application and follow local plumbing codes.
- Use appropriate sealants (PTFE tape or pipe dope) on threaded connections unless the manufacturer specifies otherwise.
- When in doubt—especially for gas lines, sewer connections, or complex systems—consult a licensed plumber or the relevant code authority.
