Plain definitions of 35 terms we use on the job in Kent.
Term Index
Open any term below for a dedicated definition page.
An air gap is an open space between a water outlet and the receiving container or drain. The space stops contaminated water from flowing backward into a clean water supply. Plumbing fixtures, dishwashers, and backflow prevention assemblies may use an air gap where a physical break protects drinking water.
Also called: Air Gap Faucet
Anode Rod is a metal component inside a tank water heater that helps protect the steel tank from corrosion. The rod attracts corrosive activity in the water, so the rod wears down before the tank does. This protective part supports water heater service and can affect the heater’s remaining service life.
Also called: Sacrificial Anode
Backflow is the unwanted movement of water in the opposite direction from normal flow. It can draw contaminated water into a clean drinking water supply when pressure changes or a connection allows reversal. Plumbing systems use air gaps and backflow preventers to stop this movement and protect water quality.
Also called: Backflow Contamination
A backwater valve is a sewer-line device that helps stop wastewater from flowing backward into a building. The valve opens when wastewater moves toward the public sewer and closes when flow reverses. It is installed on a building drain or sewer lateral, where it can protect lower fixtures from a sewer backup.
Also called: Sewer Backwater Valve
A ball valve is a quarter-turn shutoff device that controls water flow through a pipe. Inside the valve, a drilled ball rotates against sealed openings. Turning the handle aligns the opening for flow or blocks it completely. Ball valves are common on water lines because they close quickly and provide clear open or closed positions.
Also called: Shutoff Ball Valve
Cleanout is a capped access point in a drain or sewer pipe that lets a plumber inspect, clear, or flush the line. The opening connects to the pipe through a fitting and stays sealed during normal use. A cleanout may appear indoors, outdoors, near a building drain, or along a sewer lateral.
Also called: Drain Cleanout
A compression fitting is a plumbing connector that joins pipes or tubing without soldering, threading, or glue. The fitting uses a threaded nut and a compression ring, also called a ferrule. Tightening the nut presses the ring against the pipe and fitting body, creating a sealed connection for many water line repairs.
Also called: Compression Connector
A drain auger is a flexible cable tool that clears clogs inside drain pipes. The cable moves through the pipe and breaks apart or pulls back buildup. A hand crank or powered motor turns the cable. Plumbers select the cable size and tip based on the drain, clog, and pipe condition.
Also called: Plumbing Snake
An expansion tank is a small container connected to a closed water heating system. It holds air on one side of a flexible diaphragm and water on the other. As heated water expands, the tank absorbs the added volume. This helps control pressure and reduces stress on pipes, fittings, and the water heater.
Also called: Thermal Expansion Tank
A fill valve is a toilet tank component that opens to let fresh water enter after a flush. The valve closes when the tank reaches its set water level. A working fill valve helps the toilet refill quietly and prepares the tank for the next flush.
Also called: Toilet Fill Valve
A fixture shutoff valve is a small control valve installed on a water supply line near one fixture. The valve lets you stop water to that fixture without turning off the building’s main supply. Common uses include toilets, sinks, and faucets. The valve may have a lever, knob, or compression connection.
Also called: Fixture Stop Valve
Flapper Valve is a toilet tank seal that covers the flush valve opening. When you press the handle, the flapper lifts and lets tank water enter the bowl. After the flush, the flapper drops back into place and seals the opening. A worn or poorly fitted flapper can cause continuous running.
Also called: Toilet Flapper
Galvanized Pipe is a steel or iron pipe coated with zinc to slow corrosion. The coating protects the outer surface, while the metal body carries water through a building. Galvanized pipe was common in older water supply systems, but rust can narrow the passage and reduce water flow over time.
Also called: Galvanized Steel Pipe
A Leak Sensor is a small device that detects unwanted water and sends an alert when moisture reaches its sensing area. Many models sit near water heaters, washing machines, sinks, or other plumbing fixtures. Some sensors also monitor temperature or connect to a shutoff system that can stop water flow.
Also called: Water Leak Sensor
A main shutoff valve is the control that stops water flow into a home or building. The valve sits on the incoming water line, often near the meter or where the line enters the structure. Closing the valve can limit water damage during a burst pipe, major leak, or water line repair.
Also called: Main Water Shutoff
A P-Trap is a curved drain fitting that holds a small amount of water below a sink, shower, tub, or other fixture. The water blocks sewer gases from moving through the drain opening. The trap also connects the fixture drain to the building’s waste pipe and can collect small debris.
Also called: U-Bend
Pipe bursting is a trenchless sewer repair method that breaks an old buried pipe while pulling a new pipe through the same path. A bursting head moves through the existing line and pushes broken pieces into the surrounding soil. The method can replace a damaged sewer line with less surface digging than open excavation.
Also called: Pipe Splitting
Pipe Insulation is a protective covering that slows heat transfer through plumbing pipes. It helps hot water stay warm and cold water stay cool. On cold-water lines, insulation can reduce condensation. In freezing weather, it can slow heat loss, but it cannot stop freezing when exposure lasts long enough.
Also called: Pipe Wrap
Pressure Reducing Valve is a plumbing control device that lowers incoming water pressure to a set level for a building’s plumbing system. The valve helps protect pipes, fixtures, and appliances from excessive pressure. It is commonly installed on the main water line after water enters a home or other building.
Also called: Pressure Regulator
A Pressure Test is a plumbing check that applies controlled air or water pressure to a pipe system. The test shows whether the system holds pressure or loses it through a leak. Technicians use the result to check new water lines, repaired sections, or connections before the piping returns to service.
Also called: Plumbing Pressure Test
Root Intrusion is a sewer line problem where tree or plant roots enter through small cracks, loose joints, or damaged pipe sections. The roots grow inside the line and catch waste, grease, and paper. This buildup can restrict flow, cause repeated backups, and worsen pipe damage as the roots expand.
Also called: Tree Root Intrusion
Sewer Belly is a sag or low section in a buried sewer pipe. The dip interrupts the pipe’s intended slope, so wastewater can collect there instead of flowing freely. Solids may settle in the low spot, which can lead to slow drains, recurring backups, or blockages when the condition becomes severe.
Also called: Sewer Sag
A sewer cleanout is an access point in a drain or sewer line. The removable cap lets a plumber reach the pipe with a drain cable, inspection camera, or other equipment. Cleanouts may sit outdoors, near a building, or inside, depending on the property’s plumbing layout.
Also called: Sewer Access Cleanout
A sewer lateral is the private underground pipe that carries wastewater from a building's plumbing drain to a public sewer main or another approved connection point. The pipe may run beneath a yard, driveway, or street. Its condition can affect drainage, backups, and the need for sewer line replacement.
Also called: Lateral Sewer Line
A Sump Pump Float Switch is a control device that starts and stops a sump pump as the water level changes. The switch floats on rising water or moves along a fixed guide. Its position signals the pump to remove water from the sump pit before the pit overflows.
Also called: Float Switch
A tankless heat exchanger is the part of a tankless water heater that transfers heat into flowing water. A burner or electric element heats the exchanger, while water passes through separate channels. The heated water then travels to a faucet, shower, or appliance without storage in a large tank.
Also called: Plate Heat Exchanger
Thermal Expansion is the increase in water volume as water heats. In a closed plumbing system, the added volume raises water pressure because water has nowhere to move. A water heater installation may need an expansion tank to absorb that pressure and help protect pipes, fixtures, and the heater.
Also called: Water Heater Thermal Expansion
A Toilet Flange is a fitting that connects a toilet’s outlet to the drainpipe and anchors the toilet to the floor. The flange sits at floor level and provides the sealing surface for the toilet’s wax ring or another approved seal. A sound flange helps keep the toilet stable and prevents wastewater leaks.
Also called: Closet Flange
A toilet wax ring is a soft sealing gasket placed between a toilet base and the toilet flange. The ring compresses under the toilet’s weight and closes the joint around the drain opening. This seal helps keep wastewater and sewer gases from escaping where the toilet connects to the bathroom drain.
Also called: Wax Seal
Water Hammer is a pressure surge that occurs when moving water stops or changes direction quickly inside a pipe. The surge can create banging, knocking, or vibrating sounds. It may stress pipe joints, valves, and connections. Fast-closing fixtures and loose pipe supports often make the noise more noticeable.
Also called: Hydraulic Shock
A water heater dip tube is a pipe inside a tank water heater that directs incoming cold water toward the tank bottom. This placement keeps cold water away from the hot water outlet near the top. A damaged tube can send cold water upward too soon and reduce the heater’s hot water supply.
Also called: Dip Tube
A Water Heater Element is an electric heating part inside a storage water heater. The element transfers electrical energy into the water around it. A thermostat controls when the element turns on and off. Electric water heaters may have separate elements for different sections of the tank, and either element can fail.
Also called: Heating Element
Water Pressure is the force that moves water through supply pipes, valves, and fixtures. The force comes from the public water main, a private pump, or the height of stored water. Pressure affects how strongly water leaves a faucet and whether plumbing equipment receives a steady supply during use.
Also called: House Water Pressure
A Water Shutoff Valve is a plumbing control that stops water flow through a supply pipe. You can close the valve during a leak, fixture repair, or water line repair. Valves may serve the whole building or one fixture, and their handles can turn, lift, or move through a quarter-turn.
Also called: Stop Valve
Water Softener Resin is a filtering material inside a water softener tank that removes hardness minerals from household water. The resin consists of small beads that exchange minerals such as calcium and magnesium for sodium or potassium ions. Over time, the beads become full and need regeneration so the softener can keep working.
Also called: Ion Exchange Resin
