flowthough

Flowthrough, sometimes written flow-through or flow through, is a term used across disciplines to denote a design or process in which a substance, energy, or signal passes continuously through a system, rather than being stored or accumulated.

In engineering and chemistry, flow-through designs are used for reactors, filtration membranes, and chromatographic systems. They enable continuous processing, defined residence times, and scalable production. In environmental contexts, flow-through processes describe wetlands, channels, or reactors through which water or wastewater moves, allowing removal of contaminants.

In finance, flow-through refers to pass-through taxation: income from an entity flows to owners and is taxed at personal rates, avoiding corporate-level tax. The term applies to entities such as partnerships, limited liability companies, and S corporations in the United States. It also appears in Canada as flow-through shares, enabling the renunciation of exploration costs to investors who then claim deductions.

Flow-through can also describe ventilation or cooling arrangements where air or liquid streams pass through a space or device for treatment or heat exchange, rather than recirculating. This usage is common in building design, process equipment, and laboratory settings.