OBC Plumbing All Buildings key terms

The lowest piping of a drainage system that receives waste from inside the building and conveys it to the building sewer, ending 30 inches outside the building wall.

The piping that carries sewage from the building drain to the public sewer, private disposal system, or other point of disposal, starting outside the building wall.

A dimensionless measure of the probable load a plumbing fixture places on the drainage or water supply system, used to size pipes based on expected simultaneous use.

The depth of water stored in a trap that prevents sewer gas from passing into the building, typically required to be between two and four inches deep.

A U-shaped fitting that retains a water seal to block sewer gases while allowing wastewater to flow through, required at each fixture unless exempted.

The portion of a fixture drain between the trap weir and the vent fitting, whose length is limited by pipe size to preserve the trap seal.

An accessible opening with a removable plug or cover installed in drainage piping to allow clearing of blockages by rodding or other maintenance methods.

A vertical pipe that provides air circulation to the drainage system and extends from the drain line to open air above the roof, protecting trap seals.

The extension of a soil or waste stack above the highest horizontal drain connected to it, serving to vent that stack to the outdoors.

The open end of a vent pipe that extends above the roof to admit air and release gases, subject to height and distance rules from openings.

A one-way valve that admits air into drainage piping to equalize pressure but prevents sewer gas from escaping, used where venting to open air is impractical.

A vent pipe that also serves as a drain for fixtures other than the fixtures it vents, permitted only under specific size and arrangement conditions.

A single vent pipe that serves two or more fixtures or traps, connecting their individual vent lines together above the highest fixture served.

A device installed in a water supply line that prevents contaminated or polluted water from reversing flow into the potable water distribution system.

Any actual or potential link between the potable water supply and a source of contamination or pollution, which must be eliminated or protected by an approved device.

A physical separation between the free-flowing discharge end of a water supply pipe and a receiving fixture or vessel, providing the highest level of backflow protection.

A loud banging or knocking in water piping caused by the sudden stopping of water flow, typically controlled with arrestors or shock absorbers.

A device that lowers incoming water supply pressure to a safe, usable level for the building distribution system, protecting fixtures and piping from excess stress.

The increase in water volume as it is heated in a closed system, which can raise pressure and requires control by an expansion tank or relief device.

A safety device on water heaters that opens to discharge water when temperature or pressure exceeds set limits, preventing tank rupture or explosion.

An appliance that heats and stores potable water for domestic use, subject to installation rules for relief valves, venting, and seismic or thermal protection.

A device installed to separate and retain harmful or undesirable substances such as grease, oil, sand, or solids from wastewater before it enters the drainage system.

An interceptor that captures fats, oils, and grease from kitchen wastewater by slowing flow and allowing the grease to float for periodic removal.

Wastewater containing chemicals, acids, grease, or other substances that require pretreatment or special handling before discharge to the drainage system or sewer.

The piping and collection components that convey rainwater and other clear water from roofs, yards, and surfaces to an approved point of disposal.

A fitting installed on a roof to collect rainwater and direct it into the storm drainage system, sized according to roof area and rainfall intensity.

A pump installed in a pit or basin to remove accumulated water from a building or site and discharge it to an approved drainage location.

A device installed in a drainage line that closes automatically to prevent sewage from reversing into the building during a sewer backup.

A plumbing fixture designed and installed to be usable by persons with disabilities, meeting reach, clearance, and operating force requirements.

A securely mounted rail installed near accessible fixtures to provide support and stability for users, with specified size, spacing, and load capacity.

An enclosed toilet space with required dimensions, clear floor area, door swing, and grab bar locations so it can be used by a person using a wheelchair.

A pressure test in which a drainage or water piping system is filled with water and checked for leaks at a specified pressure for a required duration.

A test in which compressed air is introduced into piping and pressure is monitored to confirm the system is gas-tight and free of leaks.

The stage of plumbing work in which pipes, fittings, and supports are installed before fixtures and finished surfaces are put in place for inspection.

Official authorization issued by the authority having jurisdiction before plumbing work begins, ensuring plans and contractors meet code requirements.

The organization, office, or individual responsible for enforcing code requirements, approving materials and methods, and issuing permits and inspections.

Water that is safe for human consumption and meets health and quality standards, free of harmful levels of contaminants and pathogens.

The total measured length of piping along its centerline, including fittings and changes of direction, used for sizing and vent distance calculations.