Water-treatment proposals can become difficult to compare when the vocabulary changes from company to company. This glossary uses practical homeowner definitions and avoids turning technical terms into unsupported marketing claims.
How to use this glossary
Use the definitions as a starting point, then ask for the exact product documentation when a term is being used to justify a specific performance, certification, capacity or maintenance claim.
Glossary
Activated carbon
A porous filtration media commonly used for adsorption of certain taste, odor and chemical compounds. Actual performance depends on the media and system design.
Brine tank
The tank that holds salt/brine used to regenerate a conventional ion-exchange water softener.
Bypass valve
A valve arrangement that allows water to bypass treatment equipment for service or isolation.
Catalytic carbon
A modified carbon media used in some applications where enhanced catalytic activity is useful. Performance should be tied to the actual media/system.
Control valve
The valve that controls service flow, regeneration/backwash cycles and programming on many tank-based systems.
GPG
Grains per gallon, a common U.S. unit for water hardness.
Hardness
Primarily dissolved calcium and magnesium that can contribute to scale and spotting.
Ion exchange
A process used by conventional water softeners to exchange hardness ions for other ions on a resin bed.
Media
The material inside a filter or treatment vessel that performs the treatment function, such as carbon or ion-exchange resin.
Micron
A unit of size often used to describe particle filtration. A micron rating does not by itself describe all filter performance.
Regeneration
The cycle that restores ion-exchange resin so a softener can continue removing hardness.
Reverse osmosis (RO)
A pressure-driven membrane treatment process commonly used for point-of-use drinking water.
RO membrane
The semipermeable membrane that performs the primary separation step in an RO system.
Sediment filter
A filter designed to capture particulate matter. Selection depends on particle size, flow and application.
Service flow rate
The flow a treatment system is intended to handle while providing its designed treatment performance.
TDS
Total dissolved solids, generally a broad estimate of dissolved material. It does not identify individual contaminants.
Treatment train
Two or more treatment stages arranged in sequence to address different water conditions.
UV
Ultraviolet treatment used in certain applications for microbial control. It requires application-specific design and maintenance.
Well water
Water supplied by a private well rather than a municipal utility. Property-specific testing often plays a larger role in treatment design.