Skip to content
Free Shipping on all orders!
Free Shipping on all orders!

Understanding Common Water Terms

Here's a comprehensive list of terminology surrounding water and water filtration to know when purchasing.

Activated Carbon

Activated Charcoal, Charcoal, Activated Coal, Carbon, GAC

A broadly utilized water filtration medium frequently used for organics removal, dichlorination, and other specialty processes. Base products include but are not limited to bituminous coal, lignite, and coconut.


Dealkalizer, Alkaline Water, M-Alkalinity, P-Alkalinity

The quantitative capacity of water to neutralize an acid; that is, the measure of how much acid can be added to a liquid without causing a significant change in pH. Alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have high alkalinity. Alkalinity is expressed in mg/L of equivalent calcium carbonate in the water industry.

Anion Resin

Organic Scavenger Resin, Type II Anion, Type 1 Anion, Tannin Resin, Weak Base Anion, WBA, Strong Base Anion, SBA, White stuff

An ion with a negative charge. Anion Exchange is an ion exchange process in which anions in solution are exchanged for other anions from an ion exchanger.


Softener Bed, Softener Bed, Filter Bed, Resin Bed

The mass or volume of ion exchange resin or other media through which the water passes in the process of water treatment.


Saline, Saturated Brine, Salt Solution

A strong solution of salt(s), usually sodium chloride and other salts too. Sodium or potassium chloride brine is utilized in the regeneration state of anion and/or cation exchange water treatment equipment. Sodium chloride brine saturation in an ion exchange softening brine tank’s about 26% NaCI by weight at 60° F.

Brine Tank

Brine Measuring Tank, Brine Holding Tank, Brine Maker, Salt Tank, Brine Keeper, Salt Bale, Trash Can

A brine tank holds the brine solution utilized in conjunction with water treatment equipment. The brine’s utilized to regenerate the resin.

Calcium Scale

Calcium is one of the principal elements making up the crust of the earth. When calcium compounds are dissolved, they make water hard. The presence of calcium in water is a factor contributing to the formation of scale and insoluble soap curds, which are a means of clearly identifying hard water.


Catalytic, Accelerator

A substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed by the chemical reaction.

Catalyst Media

Chloramine Filter, Catalytic Conversion Filters

Those filter media can cause certain reactions to occur in water treatment, such as activated dissimilar metal alloys, manganese oxides, manganese greensand, calcite, and carbon.

Cation Resin

Softener Resin, Softener Beads, Softener Beads, Zeolite, Wek Acid Cation, WAC, Softener Resin, Strong Acid Cation, SAC

A positive charge ion. Cation Exchange is an ion exchange process in which cations in solution are exchanged for other cations from an ion exchanger.


Alkalinity Removal, Dealkalization

Alkalinity ions removal from a solution. A dealkalizer consists of a strong base anion exchange resin that exchanges chloride (the Cl ion of the NaCl) for sulfate, bicarbonate, and carbonate. When water goes through the anion resin, the sulfate, bicarbonate, and carbonate ions are exchanged for chloride ions.


Decationized Water

The cation exchange for hydrogen ions by a strong acid cation exchanger operated in the hydrogen form.


Air Stripper, VOC Tower, Forced Draft Degasifier, Decarbonator, Degassing, Degasify

The removal of dissolved gasses such as carbon dioxide, methane, hydrogen sulfide, and oxygen by: 1) subjecting the water to a pressure below atmospheric pressure (vacuum degassing) or 2) passing large amounts of air thoroughly through the water at atmospheric pressure (air stripping).


Demineralizer, Demin, DI

The removal of all ionized minerals and salts (both inorganic and organic) from a solution by a 2-phase ion exchange procedure. Initially, by a cation exchange resin, positively charged ions are removed in exchange for a chemically equivalent amount of hydrogen ions. Secondly, ions that are negatively charged are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange.


Silica Removal

The process of ion exchange is made for the reduction of silica from a water supply. Usually, a strong base anion exchanger operated in the OH- form is utilized.

DI Exchange Tanks

Portable Exchange Deionization, PEDI Tanks

Tanks that are rented or leased to a facility lack the means to regenerate the medium, typically ion exchange resin.

Drinking Water System

Reverse Osmosis System, Water Filtration Equipment, Drinking Water Filter

A drinking water system’s the name for the collective unit of equipment that conditions, filters, and purifies water utilized for drinking. Drinking water systems usually use multi-step filtration processes.

Effective Size

Mesh Size, Average Size

Diameter measurement of particles in a resin bed or media bed. Effective size’s that mesh size which will allow 10% of the particles of the bed to pass and will retain that remaining 90%; in other words, that size for which 10 percent of the media grains or particles are smaller and 90 percent are larger.


Boiler Feed Water, Makeup Water, Boiler Make Up Water, Feed Water

The water to be treated is fed into a given water treatment system.


Contaminant Reduction

Filtration is the physical process of removing suspended, gaseous, biological, or chemical solid contaminants from water via a filter medium.


Feet per Second, M3/Hr, Gallons Per Minute, GPM

The quantity of water or regenerant which passes a given point in a specified unit of time is often expressed in US gpm (orL/min). Flow rate in filter’s typically measured in gpm/sq. ft of bed area. In ion exchangers, it’s expressed in gpm/cu.ft of resin. Flow rate’s a critical design parameter by which the effectiveness of the water treatment unit is measured.


Well Water, Ground Water

Water is found beneath the surface of the ground. Groundwater is primarily water that has seeped down from the surface by migrating through the interstitial spaces in soils and geologic formation.


Hard Water, Water Hardness

A common quality of water that contains dissolved compounds of calcium and magnesium and, sometimes, other divalent and trivalent metallic elements. The term hardness was originally applied to waters that were hard to wash in, referring to the soap-wasting properties of hard water. Hardness stops soap from lathering by causing the creation of an insoluble curdy precipitate in the water; hardness typically causes hardness scale build-up (such as seen in boilers and in cooking pans). Magnesium salts and dissolved calcium are mainly responsible for most scaling. Hardness is usually expressed in grains per gallon (or ppm) as calcium carbonate equivalent.

Hydrogen Sulfide

Sulphur, Rotten Egg Smell, Sulfur

A flammable and corrosive gas frequently found dissolved within well water and often goes with low pH values and iron. The odor of water with as little as 0.5 milligrams per liter (mg/L) of hydrogen sulfide concentration’s detectable by many people. Concentrations less than one mg/L give the water a "musty" or "swampy" odor. Over one mg/L hydrogen sulfide concentration makes the water have the odor of a "rotten egg" and it makes the water corrosive to plumbing.

Ion Exchange

Demineralization, Water Softening

Ion exchange is referred to the process that happens when a specially charged resin lures undesirable ions in water, trapping them in the resin bed, and exchanging them for more desirable ions. For example, a water softener uses ion exchange to replace hard water calcium and magnesium ions with sodium ions.

Makeup Water

Boiler Makeup Water, Cooling Tower Makeup Water

Treated water is added to the water loop of a boiler circuit or cooling tower to make up for the water lost by steam leaks or evaporation.

Mixed Bed

Mixed Bed Resin, Mix Bed

The intermix of two or more filter or ion exchange products in the same vessel during a service run.


Rebed, Resin Replacement, Water Softener Resin Rebed

Complete removal and replacement of the media or resin from a tank is considered a re-bed. Adding to a resin bed that may have lost resin is considered "topping off."


Regeneration Cycle

The chemical solution (regenerant) use to move the contaminant ions deposited on the ion exchange resin throughout the service runs & replace them with the kind of ions needed to restore the capacity of the exchange medium for reuse.


Cation Resin, Anion Resin, Cation Exchange Resin, Ion Exchange Resin

As used in the water processing industry, this term refers to ion exchange resin products which are generally specifically-manufactured organic polymer beads utilized in softening and other ion exchange processes to have dissolved salts removed from water.

Reverse Osmosis

RO, Membrane Filtration

Reverse Osmosis is a water filtration process, where water is forced through a fine porous membrane under high pressure. Impurities in the water are trapped in the microscopic pores of the membrane.

Sulfur Water

Rotten Egg Smell, Hydrogen Sulfide Water, Smelly Water

Sulfur water occurs when high levels of hydrogen sulfide are present in water, giving it a "rotten egg" smell.


Drum, Housing, Container, Reservoir, Canister

That part of a water treatment system contains the filter medium or ion exchange resin.


Any type of group of water-soluble, natural organic phenolic compounds that’re made by metabolism in plants and trees, and are part of the degradation-resistant fulvic acid materials formed throughout the vegetation decomposition. Tannins can impart a faintly yellowish-to-brown color to water. Tannin molecules tend to form anions in water above pH 6 and can then be treated with anion exchange resins. Below pH 5, tannins are better treated with activated carbon.

Total Dissolved Solids (TDS)

TDS, Dissolved Solids, Dissolved Minerals

Total Dissolved Solids (TDS) refers to the total amount of dissolved minerals, salts, and metals in water. TDS is typically measured in milligrams per liter of water (mg/L) or parts per million (ppm).

UV Light

UV, Ultraviolet Light

Radiation (light) of a wavelength shorter than 3900 angstroms (Å), the wavelengths of visible light, and longer compared to 100 angstroms, the x-rays’ wavelength. This wavelength puts ultraviolet light at the invisible violet end of the light spectrum. Ultraviolet light’s utilized as a disinfectant.

Water Softener

Water Conditioner, Water Softening System

A water softener uses an ion exchange process to remove the minerals responsible for water hardness, typically calcium and magnesium.

Water Softener Salt

Water Softening Pellets, Sodium Chloride, Softening Salt, Solar Salt

Water softener salt’s utilized to recharge the water softener resin throughout regeneration, which attracts hard water minerals throughout the softening process.

Water Softening

The reduction or removal of calcium and magnesium ions, which are the principal cause of hardness in water. The cation exchange resin method is most commonly water treatment. In municipal and industrial water treatment, the process can be lime-soda softening or lime softening.

Please Note: This document is designed as a guide for household water treatment, not a recommendation. Before installing a household water treatment system, contact your local health department’s environmental health group for consultation.