ID Plumber key terms

The organization, office, or individual responsible for enforcing a code's requirements, approving materials and methods, and granting interpretations or variances. The local building or plumbing official usually fills this role.

The formal legal process by which a jurisdiction enacts a model plumbing code, often with local amendments, so that it becomes enforceable law within that jurisdiction's boundaries.

A written authorization issued by the AHJ allowing specified plumbing work to proceed. It creates an inspection record and is required before concealed work begins in most jurisdictions.

The AHJ's on-site verification that installed work matches approved plans and code. Common stages include rough-in, underground, and final; work must pass each before being covered or placed in service.

The stage of plumbing installation completed before walls, floors, or ceilings are closed, including piping, fittings, and supports. It must be inspected and approved before concealment.

Pipe installed inside walls, floors, ceilings, or chases so it is hidden from view. It must be tested and inspected before being covered and must remain accessible where the code requires access.

A removable cover providing entry to concealed valves, cleanouts, or fixtures for inspection, testing, repair, or replacement without destructive demolition of the surrounding finish.

A dimensionless measure of the probable load a fixture places on the drainage or water supply system, based on its flow rate and use frequency. Values let dissimilar fixtures be summed into one design load.

A unit expressing the drainage load of a fixture relative to a fixture draining one cubic foot per minute. DFU values are summed to size branches, stacks, and building drains.

A unit expressing a fixture's demand on the water distribution system, accounting for flow rate and probability of simultaneous use. Total WSFU guides pipe sizing and pressure-loss calculations.

The vertical water column retained in a trap's dip that blocks sewer gas from entering the building. Its depth is measured between the trap weir and the top of the trap dip.

The top edge of the trap outlet over which water must flow before draining away. The weir establishes the normal water level and thus the retained depth of the trap seal.

The pipe section between a trap weir and its connection to a vented drain or branch. Its length is limited by code to control self-siphonage and preserve the trap seal.

A trap whose outlet turns downward immediately after the weir, creating a double bend. It is prohibited because the falling water tends to siphon the seal out.

A U-shaped trap with a horizontal outlet after the weir and a swivel or union connection. It is the standard fixture trap and is permitted where properly vented and accessible.

A vertical vent pipe extending through the roof that provides air to drain lines. It protects trap seals by limiting pressure fluctuations in the drainage system.

The extension of a soil or waste stack above the highest fixture connection, serving as a vent. It relieves pressure in the stack and connects to the vent system.

The open end of a vent pipe above the roof that admits air and discharges gases. Code sets minimum height above roof, distance from openings, and clearance requirements.

An unobstructed vertical separation between a water supply outlet and the flood-level rim of a receptor. It is the most reliable backflow prevention method for indirect waste connections.

A device or assembly that prevents reverse flow of contaminated water into the potable supply. Types include reduced-pressure zone assemblies, double check valves, and vacuum breakers, selected by hazard level.

Any actual or potential link between the potable water system and a source of contamination or pollution. Cross-connections must be eliminated or protected by an approved backflow preventer.

The pressure surge caused when flowing water is stopped abruptly by a fast-closing valve. It produces banging noise and can damage piping; arrestors or slow-closing valves mitigate it.

A device with a trapped air chamber or piston that absorbs the shock wave from sudden valve closure. It is installed near quick-closing fixtures to protect piping and fittings.

A device that lowers incoming street pressure to a safe, usable level for the building's distribution system. It protects fixtures and piping from excessive pressure and is often required above a set threshold.

The total equivalent pipe length of a run, including straight pipe and the equivalent lengths of fittings and valves. It is used with friction-loss tables to size pipe and check pressure.

The pressure drop caused by water moving through pipe, fittings, and valves. Sizing must keep total loss low enough that the farthest fixture still receives adequate flow and pressure.

The pressure exerted by water at rest, equal to about 0.433 psi per foot of vertical height. It establishes the available pressure at a fixture before flow losses are subtracted.

The lowest horizontal pipe that receives soil and waste from inside the building and conveys it to the building sewer. It extends to a point about five feet outside the building wall.

The pipe carrying sewage from the building drain to the public sewer or private disposal system. It begins outside the building foundation and is often governed by separate rules.

An accessible fitting with a removable plug that allows a drain line to be rodded or jetted. Code specifies placement at changes in direction, long runs, and the base of stacks.

A vertical pipe that carries toilet and other soil waste from fixtures down to the building drain. It usually extends upward as a stack vent.

A vertical pipe conveying liquid waste from fixtures other than water closets. It may be combined with a soil stack or run separately depending on the design.

The downward pitch of a horizontal drain, expressed as a ratio or percentage. Adequate slope keeps solids moving while limiting velocity; insufficient slope causes clogging.

A device that separates fats, oils, and grease from kitchen wastewater before it enters the sewer. It must be sized to flow and cleaned regularly to remain effective.

A receptacle that traps and retains specific undesirable substances such as grease, sand, or oil before allowing wastewater to pass to the drainage system. It requires periodic maintenance and access.

Liquid waste that discharges into the drainage system through an air gap or air break rather than a direct connection. This protects potable water and fixtures from contamination.

Wastewater from sinks, showers, bathtubs, and laundry that excludes toilet and kitchen waste. It may be reused for irrigation or flushing where local rules permit and treatment is adequate.

Treated wastewater approved for beneficial reuse such as irrigation or industrial processes. It must be conveyed in clearly marked, separate piping with backflow protection from potable supplies.

Pipe and tubing that conveys natural gas or propane from the meter or tank to appliances. Installation follows fuel gas code rules on materials, sizing, support, and testing.

A short, capped vertical drop installed at the appliance connection to collect dirt and condensate before gas enters the controls. It must be located close to the appliance inlet.

Another name for a sediment trap: a capped vertical extension at an appliance gas connection that captures debris and moisture. It protects gas valves and orifices from fouling.

Selecting pipe diameter so that flow, pressure, and velocity meet demand without excessive loss. It uses fixture units, developed length, and friction tables, plus gas-specific charts for fuel gas.

A three-dimensional-style plumbing drawing showing piping runs, fittings, and fixtures at angles. It helps installers visualize routing and count fittings for takeoffs and sizing.

A drawing showing the layout of fixtures and piping as seen from above. It is used with riser diagrams to plan routes and verify code clearances.

A schematic drawing showing vertical relationships among stacks, fixtures, and drains without true scale. It is used to verify venting and drainage connections.