IAPMO PPE key terms

A model plumbing code that sets minimum requirements for the design, installation, and inspection of plumbing systems, adopted as law by many jurisdictions and administered by IAPMO.

The official or agency responsible for enforcing code requirements, approving materials and methods, and granting interpretations or variances within a given jurisdiction.

A written authorization issued by the AHJ allowing specified plumbing work to proceed, ensuring the work is reviewed and inspected before being concealed or placed in service.

The stage of installation where piping, fittings, and supports are placed but fixtures and trim are not yet set, allowing inspection before concealment by walls or finishes.

An official review of installed plumbing work by the AHJ to verify compliance with the code at required stages such as rough-in, final, and testing.

A published technical document defining material composition, dimensions, testing, or performance criteria referenced by the code to qualify products for use.

Equipment or materials included in a published list by an approved testing agency, indicating they meet a recognized standard and are acceptable for the intended use.

Accepted by the AHJ as meeting code requirements, whether through listing by a recognized agency or by other evidence the jurisdiction finds satisfactory.

Independent verification by a recognized testing agency that a product complies with a referenced standard, supporting its acceptance as listed or approved equipment.

A unit of measure expressing the probable discharge rate of a fixture relative to a fixture draining one cubic foot per minute, used to size drainage piping.

A measure of the probable demand a fixture places on the water distribution system, accounting for flow rate and use frequency, used to size supply piping.

The combined drain, waste, and vent piping network that carries sewage and greywater away from fixtures while admitting air to protect trap seals.

The lowest piping of a drainage system that receives the discharge from soil, waste, and other drainage pipes inside the building and conveys it to the building sewer.

The piping that begins outside the building wall and carries sewage from the building drain to the public sewer or private disposal system.

The drain pipe that connects a fixture's trap to the drainage system, sized according to the fixture's drainage fixture unit load.

A U-shaped fitting that retains a water seal to prevent sewer gas from entering a building while allowing wastewater to pass through.

The depth of water held in a trap, typically between two and four inches, that blocks sewer gas from moving through the fixture into occupied space.

The portion of a fixture drain between the trap weir and the vent connection, limited in length by pipe diameter to preserve the trap seal.

A vertical vent pipe that extends through the roof and provides air to the drainage system, preventing pressure imbalances that could siphon trap seals.

The extension of a soil or waste stack above the highest horizontal drain connected to it, terminating in open air to relieve pressure in the stack.

A vertical pipe that carries the discharge of water closets and may also receive other fixtures, connecting to the building drain below.

A one-way mechanical vent that admits air into drainage piping when pressure drops but closes to prevent sewer gas from escaping into the building.

An accessible fitting with a removable cap that allows a drain or sewer line to be cleared of blockages by rodding or jetting.

The downward fall of horizontal drainage pipe, expressed in inches per foot, needed to move waste by gravity while carrying solids and limiting scouring.

The primary public or private water supply pipe that delivers potable water to buildings and from which service lines and fire lines branch.

The pipe that conveys potable water from the water main or meter to the building's water distribution system.

A device installed on a service line that measures and records the volume of water delivered to a building for billing and consumption tracking.

The supply pipe that runs from a main or riser to one or more individual fixtures, sized using water supply fixture unit demand.

A device that lowers incoming water pressure to a safe, usable level downstream, protecting fixtures and piping from excessive stress.

A device containing a trapped air chamber or piston that absorbs the shock wave created when water flow stops suddenly in a piping system.

The increase in water volume as it is heated, which raises pressure in a closed system and must be relieved by an expansion tank or relief valve.

Water that is safe for human consumption, meeting health standards for contaminants and protected from cross-connections throughout the distribution system.

Any actual or potential link between a potable water system and a source of contamination or pollution that could allow unwanted material to enter the drinking water.

The unwanted reversal of water flow in a distribution system, caused by backsiphonage or backpressure, that can carry contaminants toward potable supplies.

Backflow caused by negative or reduced pressure in the supply piping, which draws nonpotable liquids into the system through a cross-connection.

Backflow caused by downstream pressure exceeding supply pressure, forcing water or another fluid backward into the potable distribution system.

An unobstructed vertical separation between a water supply outlet and the flood-level rim of a receiving fixture, providing the highest level of backflow protection.

An assembly or device installed to stop reverse flow, such as a reduced-pressure zone assembly, double check assembly, or vacuum breaker, selected by hazard level.

A testable backflow preventer with two check valves and a relief valve that maintains a pressure differential, protecting against both backsiphonage and backpressure hazards.

A device that admits air into piping to break a vacuum and prevent backsiphonage, available in atmospheric, pressure, and hose-connection types.