Plain definitions of 35 terms we use on the job in Auburn.
Term Index
Open any term below for a dedicated definition page.
ABS pipe is a rigid plastic drain pipe made from acrylonitrile butadiene styrene. It carries wastewater through building drains and sewer lines. The pipe has a smooth inside surface that helps wastewater flow. Plumbers join ABS sections with fittings and solvent cement to create a sealed drainage path.
Also called: Acrylonitrile Butadiene Styrene Pipe
An air gap is an open space that separates a water supply from a drain or other possible contamination source. The space stops dirty water from flowing backward into the clean water line. Air gaps commonly appear at sink-mounted dishwasher connections and other plumbing points that need backflow protection.
Also called: Air Gap Fitting
An anode rod is a metal component inside many tank water heaters. The rod attracts corrosive activity in the tank water, so the tank lining and other metal parts face less damage. As the rod wears away, the water heater loses this layer of protection and may need a replacement rod.
Also called: Sacrificial Anode
A Backflow Preventer is a plumbing device that keeps contaminated water from flowing backward into a clean water supply. The device uses valves, air gaps, or both to control flow direction. Common installations protect drinking water from connections linked to irrigation systems, boilers, fire systems, or other nonpotable equipment.
Also called: Backflow Prevention Device
A Ball Valve is a shutoff device that controls water flow through a pipe with a round ball inside. The ball has a drilled passage. Turning the handle lines up the passage with the pipe to allow flow, or blocks the passage to stop flow. Ball valves provide quick, direct control on water lines.
Cast Iron Pipe is a durable metal pipe used mainly for underground sewer and drain systems. Cast iron resists heat and reduces sound from flowing wastewater. Over time, rust, shifting soil, root growth, or heavy buildup can affect the pipe. Replacement work may connect new plastic pipe to sound cast iron.
A check valve is a one-way plumbing device that lets water flow forward and blocks reverse flow. The valve opens when water moves in the intended direction. It closes when flow stops or pressure changes. This action helps protect pumps, pipes, and connected equipment from unwanted backflow.
A cleanout is an accessible opening in a drain or sewer pipe. Its removable cap lets a plumber reach the inside of the line with cleaning equipment or an inspection camera. Cleanouts are placed at useful access points, such as near a building, at a pipe direction change, or along a buried sewer route.
Also called: Cleanout Access
A compression fitting is a pipe connection that seals when a nut presses a soft ring around the pipe. The fitting joins pipes or fixtures without soldering or threading the pipe. It can be removed for repairs, but the pipe and ring must stay aligned to prevent leaks.
A Drain Snake is a flexible plumbing tool that clears blockages from drain pipes. The cable moves through the pipe and breaks apart or pulls back material that stops water flow. Plumbers choose different cable sizes and heads based on the drain, the blockage, and the pipe condition.
Also called: Plumbing Snake
An expansion tank is a small pressure vessel connected to a water heater system. The tank contains air and water separated by a flexible diaphragm. As heated water expands, the tank accepts the extra volume and helps limit pressure changes in a closed plumbing system.
Also called: Thermal Expansion Tank
A flapper valve is a rubber or plastic seal inside a toilet tank that controls water flow into the bowl. The valve lifts when you press the flush handle, then drops onto the flush opening. A working flapper valve creates a seal after flushing, while a worn valve can cause running water.
Also called: Toilet Flapper
A gas shutoff valve is a control that stops gas flow through a pipe or appliance connection. Turning the valve changes the passage from open to closed. The valve gives a gas system a clear isolation point during appliance service, gas line repair, or leak investigation by a qualified professional.
Also called: Gas Isolation Valve
A Grease Trap is a plumbing device that catches fats, oils, and grease before wastewater enters a drain line. The trap slows the flow so grease can cool and separate from water. Food scraps and solid debris may also collect inside. Regular cleaning keeps the device from restricting drainage or releasing grease downstream.
Also called: Grease Interceptor
Hard Water is water that contains dissolved minerals, mainly calcium and magnesium. These minerals can leave scale on fixtures, reduce soap lather, and create deposits inside plumbing and water heaters. Hard water is common in many homes and is different from dirty water because the minerals are dissolved and usually invisible.
An Inlet Valve is a toilet tank component that opens to let fresh water enter after a flush and closes when the tank reaches its set level. The valve connects to the water supply below the tank. A float senses the water level and controls the valve during refilling.
Also called: Water Inlet Valve
PEX pipe is flexible plastic tubing used to carry hot and cold water through plumbing systems. Cross-linked polyethylene gives PEX pipe flexibility, resistance to corrosion, and simple routing around framing. Plumbers connect it with approved fittings, so it can serve supply lines in homes and many water line replacement projects.
Also called: Cross-Linked Polyethylene Pipe
A pipe fitting is a plumbing component that joins, redirects, extends, reduces, or ends a pipe run. Fittings include elbows, tees, couplings, adapters, unions, and caps. Each fitting matches the pipe material, size, connection method, and water use. A proper fit creates a sealed path that helps prevent leaks and movement.
Pipe insulation is a protective covering that surrounds plumbing pipes and helps control heat transfer. It can keep hot water warmer, reduce condensation on cold pipes, and limit heat loss in exposed areas. Common materials include foam, rubber, and fiberglass. The correct material depends on the pipe, temperature, moisture, and location.
Also called: Pipe Wrap
A Pressure Reducing Valve is a plumbing control device that lowers incoming water pressure to a safer, steadier level for a building's pipes and fixtures. The valve responds to pressure changes and adjusts the water opening as needed. It commonly sits on the main water line near where water enters the building.
Also called: PRV
PVC pipe is a plastic plumbing pipe made from polyvinyl chloride. It carries water, wastewater, and other fluids through residential and commercial systems. PVC pipe resists corrosion and has a smooth inside surface that supports steady flow. Plumbers join sections with fittings and solvent cement to form sealed pipe runs.
Also called: Polyvinyl Chloride Pipe
A sewer lateral is the private underground pipe that carries wastewater from a building's plumbing to a public sewer main or a private septic connection. The lateral may run beneath a yard, driveway, sidewalk, or street. Its condition affects how well wastewater leaves the property and reaches the larger sewer system.
Also called: Lateral Sewer Line
A shutoff valve is a plumbing control that stops water flow through a pipe or fixture supply line. Turning the handle closes an internal gate, ball, or cartridge. This lets you isolate a toilet, faucet, water heater, or section of piping during a leak, repair, or replacement.
Also called: Stop Valve
A siphon is a flow path that moves liquid from a higher level to a lower level through a curved passage. The liquid rises into the passage, then gravity pulls it downward once flow starts. In toilet plumbing, the siphon action helps carry water and waste through the bowl’s trapway during a flush.
Also called: Siphon Jet
Thermal Expansion is the increase in water volume that occurs as water heats inside a closed plumbing system. The added volume raises pressure because water cannot compress easily. In a water heater, this pressure can affect valves, connections, and fixtures. An expansion tank gives the extra water space to reduce pressure stress.
Also called: Water Heater Expansion
A Toilet Fill Valve is a toilet tank component that controls fresh water entering the tank after a flush. The valve opens when the tank level drops, then closes when the tank refills. A float senses the water level and helps prevent continuous filling, weak flushes, and water waste.
Also called: Ballcock
A toilet flange is a fitting that connects a toilet to the bathroom drain and anchors the toilet to the floor. The flange sits around the drain opening and provides a sealed mounting surface for the toilet. It works with a wax ring or similar seal to help keep wastewater and sewer gases contained.
Also called: Closet Flange
A trap is a curved or chambered section of drainpipe that holds water and blocks sewer gases from entering a bathroom. The water seal also helps keep odors and pests out of the room. Traps sit below sinks, toilets, showers, and tubs, where wastewater flows through them before reaching the drain line.
Also called: Plumbing Trap
A Trap Primer is a plumbing device that adds water to a drain trap when the trap could dry out. The added water protects the trap seal, which blocks sewer gases from entering a building. Trap Primers commonly serve floor drains in areas that receive little regular drainage.
A Vacuum Breaker is a backflow prevention device that admits air into a water line when pressure drops. The air breaks the suction that could pull contaminated water into the clean supply. Vacuum breakers commonly protect hose connections, irrigation systems, and other outlets where water may flow through an attached hose or device.
Also called: Vacuum Relief Valve
Water Hammer is a pressure shock in a plumbing system that happens when flowing water stops or changes direction quickly. The shock travels through pipes and can create banging, knocking, shaking, or movement at pipe supports. It often appears after a valve closes, a washing machine stops, or a faucet shuts suddenly.
Also called: Hydraulic Shock
A water meter is a device that measures the volume of water entering a property through its supply line. The meter records water flow for utility billing and can help show whether water is moving when fixtures are closed. Most meters sit near the property connection and include a shutoff point.
Water pressure is the force that moves water through supply pipes and plumbing fixtures. Pressure helps water reach faucets, toilets, showers, and appliances. A steady supply supports normal fixture operation, while pressure that is too low or too high can point to a restriction, leak, valve problem, or other water line issue.
A wax ring is a soft sealing gasket that sits between a toilet base and the toilet flange. It forms a watertight barrier around the drain opening and helps keep sewer gases from entering the bathroom. The ring compresses when the toilet is set in place, creating a seal without threaded connections.
Also called: Toilet Wax Seal
A Wye Fitting is a Y-shaped pipe connector that joins a branch line to a main drain or sewer pipe. Its angled branch guides wastewater into the main flow, which helps reduce sharp turns and turbulence. Plumbers use wye fittings in drainage systems where a smooth change in direction supports reliable sewer flow.
Also called: Y Fitting
