Plumbing Terms and Definitions
- Air Lock
- A blockage in the flow of a liquid, often on the suction side of a pump caused by an air bubble in the
line
- Back Pressure
- Pressure that resists the flow of fluid in a pipe system
- Backflow
- The flow of liquid into the distributing pipes of a potable water system from any source other than the
intended source
- Ball Check Valve
- A ball type valve used to prevent flow in one direction
- Ball Cock
- A valve that controls the flow of water into a tank or cistern. When the water level drops a float ball
drops allowing water into the tank. When the water level is restored the float rises and closes off the water
flow.
- Black Water
- Waste water from toilets.
- Blind Flange
- A flange that closes the end of a pipe. There is no opening for the passage of water.
- Branch
- Any part of the drainage system other than the main riser or stack.
- BTU
- British Thermal Unit. A unit of heat energy required to raise the temperature of 1lb of water by 1 degree
Fahrenheit.
- Check Valve
- A backflow preventer in a pipe run that allows water to flow in one direction only.
- C.O. - Clean-Out Plug
- A plug in a trap or drain providing access for the purpose of clearing an obstacle.
- Closet Auger
- A flexible rod used to clean out a toilet’s built-in trap.
- Closet or Floor Flange
- An anchoring ring used to secure the toilet to the floor. Also known as a “doughnut”
- Common or Dual Vent
- A drain from two or more fixtures connected to a single trap.
- Diverter
- Valves which direct water to various outlets. Used in showers, sinks and bathtubs.
- Dry Vent
- A vent that does not carry water or waste.
- DWV
- Abbreviation for a drainage system consisting Drainage, Waste and Ventilation
- Effluent
- Liquid Waste from the Septic system
- Elbow
- A pipe fitting which changes the direction of the plumbing line.
- Escutcheon
- A decorative metal or ceramic trim or flange which covers a faucet or trip lever
- Fall/Flow
- The slope or angle of a pipe line for adequate drainage
- Female Fitting or Thread
- A pipe fitting or thread into which another pipe fitting or thread is inserted
- Flap Valve
- A flap like valve, generally on the bottom of a toilet cistern, which allows water flow from the tank
to the bowl.
- Floor Drain
- Waste water drain situated on the bathroom floor.
- French Drain
- An exterior drain containing loose stone or gravel.
- Grey Water
- Waste water from sinks, showers and bathtubs.
- House Trap
- A “U” shaped pipe fitting running between the house and a sewer.
- Leader
- Pipe carrying rainwater to the ground or a sewer
- Main
- The main supply of water running to all branches.
- Male Fitting or Thread
- A pipe fitting or thread on the outside of a pipe fitting into a female pipe fitting.
- Manifold
- A fitting or pipe system connecting one pipe to more than one pipe.
- O.D.
- Outside Diameter of a pipe generally only used with copper or brass fittings
- O Ring
- Round rubber washer used to create a water tight seal
- Overhead Feed System
- A plumbing system in which water is supplied by means of gravity from a tank on top of a building.
- P Trap
- A curved waste water pipe under a sink designed to hold a water lock and prevent odors from escaping
- Peak Hour Demand
- The time of the day when the maximum water demand is expected.
- Pressure Balance Valve
- Mixing valve that maintains a balance between hot and cold water by regulating supply pressure fluctuations.
Prevents scalding.
- Reducer
- A pipe fitting which connects together two pipes of different sizes.
- Riser
- A pipe or flexible assembly connecting a faucet to a supply stop valve.
- Septic Tank
- Device or receptacle devised to expedite the decomposition of elements contained in raw sewage waste
- Sleeve
- A pipe passing through a wall which allows another pipe to pass through it
- Soil Pipe
- A pipe that conveys the discharge of water closets
- Soil Stack
- Large vertical drain to which all branch waste lines connect. Carries waste to the septic tank or sewer.
- Stack
- A vertical main in the DWV system.
- Static Lift or Head
- The vertical distance between source and discharge water levels in a pump system.
- Stop Valve
- A in-line shutoff valve found often beneath sinks and toilets.
- Storm Drain
- An external drain installed outside the foundation wall of a building generally to carry away rain water.
- Sump
- A pit or receptacle at a low point through which liquid waste is drained.
- Tee
- A T-shaped fitting with three openings.
- Trap
- A curved waste pipe holding a water lock that prevents odors from escaping.
- Trap Seal Loss
- A problem stemming from inadequate ventilation of a trap or pressure imbalance within a drainage system.
- Vent
- A pipe that allows air into a drain system to balance pressure, preventing water in the traps from being
siphoned off.
- Vent Stack
- Upper Portion of the soil stack above the highest plumbing fixture through which gases and odors escape.
- WYE
- A Y shaped fitting with three openings.