IAPMO Green Plumber key terms

A plumbing product independently certified to meet the U.S. EPA's water-saving and performance criteria, such as a toilet using 1.28 gallons or less per flush. The label helps buyers compare fixtures by verified efficiency rather than marketing claims.

The volume of water a toilet or urinal consumes in a single flush cycle, measured in U.S. gallons. It is the primary metric used to compare flush fixture efficiency and to verify compliance with plumbing code maximums.

The volume of water passing a point per minute, usually expressed in gallons per minute for faucets, showerheads, and appliances. Codes and efficiency programs set maximum rates to limit consumption without sacrificing user performance.

A small screw-on fitting at a faucet outlet that mixes air into the water stream, reducing flow while maintaining a wet, usable stream. Aerators are a low-cost retrofit that cuts lavatory water use noticeably.

A faucet insert that holds a nearly constant flow rate across a wide range of supply pressures, so a fixture does not waste water when pressure is high. It helps ensure rated flow limits are actually achieved in the field.

A toilet offering two flush volumes, typically a smaller flush for liquid waste and a larger one for solids. It reduces average water use per use compared with a single-flush fixture while meeting performance standards.

A test result reporting the mass of solid waste a toilet can reliably clear in a single flush, expressed in grams. Higher scores indicate stronger drainline carry and help specifiers pair low flush volumes with dependable performance.

The ability of a reduced flush volume to transport waste through a building drain and sewer over distance. Low-flow fixtures can fail to move solids if pipe slope or sizing is poor, so carry is evaluated during design.

A shower fixture designed to deliver a reduced flow rate, commonly 2.0 gallons per minute or less under current standards. Efficient models use spray pattern and orifice design rather than volume to maintain a satisfying shower.

Wastewater from bathtubs, showers, lavatories, and laundry that has not been contaminated by toilet discharge or kitchen waste. It can be treated and reused for subsurface irrigation or flushing where local rules allow.

Wastewater containing toilet discharge or significant organic and pathogen loading, including kitchen sink waste in many jurisdictions. It requires full treatment before reuse and is regulated more strictly than graywater.

The collection and storage of roof runoff for nonpotable uses such as irrigation, cooling tower makeup, or toilet flushing. Systems typically include first-flush diversion, filtration, and backflow protection to safeguard the potable supply.

A tank, above or below ground, that stores harvested rainwater or treated graywater for later use. Sizing depends on catchment area, rainfall patterns, and demand, and the tank must be protected from contamination and mosquito breeding.

A device that measures the volume of water delivered to a building or submetered zone. Metering enables leak detection, consumption benchmarking, and billing that rewards conservation, and is often required for green certification.

A secondary meter installed downstream of the main meter to track water use by a specific tenant, building system, or end use. Submetering supports accountability and helps operators identify abnormal consumption quickly.

A structured accounting of all water entering and leaving a facility, used to find losses, leaks, and inefficient end uses. Results guide retrofit priorities and establish a baseline for measuring conservation savings.

The process of finding unintended water loss in piping, fixtures, and equipment using metering, acoustic listening, pressure testing, or flow monitoring. Early detection protects water efficiency gains and prevents property damage.

A device that lowers incoming supply pressure to a safe, stable level for downstream fixtures and piping. Correct pressure control reduces waste from high-flow leakage and protects fittings from premature failure.

A measure of a water heater's overall efficiency, relating delivered hot water energy to total energy consumed, including standby losses. Higher values indicate a more efficient unit, though ratings vary by test method and product class.

The current federal efficiency metric for residential water heaters, replacing the energy factor and based on a standardized daily draw profile. It allows comparison across storage, instantaneous, and heat pump types under one framework.

A water heater that moves heat from surrounding air into stored water using a vapor-compression cycle rather than direct electric resistance. It can cut water heating energy substantially but needs adequate space and affects space conditioning.

A system that uses solar collectors to heat water or a transfer fluid, often backed up by a conventional heater. Design must address freeze protection, stagnation, and proper orientation to deliver expected savings.

A pump-and-return arrangement that keeps hot water circulating near fixtures to reduce the wait for hot water. It saves water wasted during warm-up but consumes pump and reheating energy, so controls and insulation matter.

A hot water control strategy that starts the circulation pump only when a user requests hot water, rather than running continuously. It captures most of the water savings of recirculation while limiting standby energy loss.

Thermal wrapping applied to hot water lines to reduce heat loss between the heater and fixtures. Well-insulated runs shorten warm-up time, saving both water and the energy used to reheat cooled water in the pipe.

A manifold-and-home-run piping layout that places small-diameter lines to each fixture from a central distribution point. It reduces the volume of water sitting in pipes, shortening hot water wait times and limiting wasted draw.

The collection and safe disposal of water produced by condensing appliances such as high-efficiency furnaces, heat pump water heaters, and air conditioners. Neutralization or proper drainage protects piping and drains from corrosion.

A boiler designed to recover latent heat from flue gas by condensing water vapor, achieving higher efficiency than non-condensing models. It produces acidic condensate that must be neutralized or piped to a suitable drain.

The air supplied to fuel-burning appliances for safe, complete combustion. Green building practice requires adequate, often sealed, combustion air to protect indoor air quality and prevent backdrafting of flue gases.

The reverse flow of combustion products down a vent into occupied space, often caused by depressurization or blocked flues. It is a serious health hazard that efficient envelope design and proper venting must guard against.

Outdoor air supplied to replace air exhausted by fans, dryers, or vent hoods so building pressure stays balanced. Adequate makeup air prevents backdrafting and helps exhaust systems perform as designed.

A device that stops reverse flow of contaminated water into the potable supply, using air gaps, check valves, or reduced-pressure zones. It is required for irrigation, boilers, and any cross-connection risk.

Any actual or potential link between the potable water system and a source of contamination. Eliminating or protecting cross-connections is a core public health requirement in plumbing codes and green reuse systems.

An unobstructed vertical separation between a water supply outlet and the flood level of a receiving fixture. It provides the highest level of backflow protection because no mechanical parts can fail.

A fixture or fitting that receives discharged waste through an air gap rather than a direct pipe connection. It protects the potable supply and drainage system from contamination while allowing needed drainage.

A device that automatically adds a small amount of water to a floor drain trap to maintain the seal. Green buildings with efficient fixtures and low traffic can let traps evaporate, allowing sewer gas into occupied space.

A harmonized set of minimum water efficiency and performance requirements for plumbing fixtures, developed to align programs across North America. It gives manufacturers and specifiers one consistent benchmark.

A voluntary green building rating system that awards points across categories including water efficiency, energy, materials, and indoor environmental quality. Plumbing choices such as efficient fixtures and metering contribute to credits.

A cap on the amount of volatile organic compounds emitted by products such as pipe cement, primers, and sealants. Low-VOC products protect indoor air quality and installer health and are favored by green rating systems.

Solder used for potable water piping that meets current low-lead content limits, typically lead-free alloys. Its use prevents lead leaching into drinking water and is required by plumbing codes for potable systems.

Flexible crosslinked polyethylene tubing widely used for potable water distribution. It resists corrosion and scale, allows fewer fittings, and supports home-run layouts, though it must be protected from sunlight and freezing.

A system that treats sewage at or near the point of generation, such as a septic system or advanced treatment unit, before dispersal or reuse. Proper siting, sizing, and maintenance protect groundwater and public health.

A urinal that uses a liquid seal or cartridge instead of flushing water to control odors and carry waste to the drain. It eliminates flush water entirely but requires correct cartridge maintenance and drainline design.