Water Terms
Alternate Terms
Definition and or Uses
Activated Carbon
Granular Activated Carbon, GAC, Carbon, Activated Coal, Activated Carbon Charcoal, Charcoal, Activated Charcoal
Activated carbon is most often used in a variety of water treatment techniques such as dechlorination and organics removal. Base products used to create activated carbon include, but aren’t limited to: bituminous coal, coconut, and lignite.
Dealkalizer, Alkaline Water, M-Alkalinity, P-Alkalinity
Alkalinity refers to the calculated amount of water’s ability to neutralize acid; or the measured amount of acid that can be combined with a liquid without drastically changing its pH levels. To clarify, alkalinity and pH are not the same. Water does not need to have a high pH level in order to achieve high alkalinity. In industry terms, alkalinity is measured as milligrams per liter (mg/L) of equivalent calcium carbonate.
Anion Resin
Strong base Anion, SBA, Weak base Anion, WBA, tannin resin, Type 1 Anion, Type II Anion, organic scavenger resin
Anion resin, also known as anion exchange resin, is an assembly of small white or yellow beads created from polystyrene material. An anion is a negatively charged ion that contains more electrons than protons. In the anion exchange process, negatively charged ions in the water are replaced with anions from the resin inside the ion exchanger.
Resin Bed, Softener bed, Filter bed, softener bed
A resin bed refers to the capacity measurement of ion exchange resin or media that water flows through during the water treatment process.
Salt Solution, Saturated Brine
Brine is a thick concentrate mixture of salts, commonly sodium chloride, and water. A brine solution of potassium or sodium chloride is used during the regeneration of cation and anion exchange equipment. The brine in an ion exchange softening tank is about 26% NaCl by weight, at 60° F.
Brine Tank
Salt Bale, Brine Keeper, Salt Tank, Brine Maker, Brine Holding Tank, Brine Measuring Tank
A brine tank is the container used to hold the brine solution, which is used in the regeneration of resin beds in water treatment equipment.
Calcium is one of the principle elements that make up the earth’s crust. Dissolved calcium compounds are responsible for hard water. Calcium in water is a major factor in the production of scale and soap scum, which are clear signs of hard water.
A catalyst is a substance that changes the yield or speed of a chemical reaction, without being altered or consumed by the process.
Catalyst Media
Catalyst Medium
Catalyst media are those filter media that cause certain reactions during water treatment. These materials include: manganese oxides, manganese greensand, activated carbon, calcite, and dissimilar metal alloys.
Cation Resin
SAC, Strong Acid Cation, Softener Resin, WAC, Weak Acid Cation, Zeolite, Softener Beads, Softner Beads, Softener Resin
Cation resin, also known as cation exchange resin, is a collection of small white or yellow beads made of polystyrene material. A cation is a positively charged ion with more protons than electrons. In the cation exchange process, positively charged ions in the water are exchanged for cations from the resin inside the ion exchanger.
Decationized Water
Decationizing is the process of exchanging cations for hydrogen ions through the use of a strong acid in a cation exchanger operating in hydrogen form.
Degasify, Degassing, Decarbonator, Forced Draft Degasifier, VOC Tower, Air Stripper
A degasifier is used to remove dissolved gasses from water supplies. These gasses include: methane, oxygen, hydrogen sulfide, and carbon dioxide. This is achieved either by vacuum degassing or air stripping. In vacuum degassing, water is subjected to pressure below atmospheric pressure. In air stripping, large amounts of air are passed through the water at atmospheric pressure.
Demineralizer, Demin, DI
A deionizer removes all ionized materials (inorganic and organic) through the use of a two-phase ion exchange process. The first step in the process is the removal of positively charged ions by a cation exchange resin, which are replaced with hydrogen ions. The second step is the removal of negatively charged ions by an anion exchange resin, which are replaced with hydroxide ions. The hydrogen and hydroxide ions then bond to form water molecules. The process is also referred to as demineralization by ion exchange.
A Desilicizer removes silica from water through an ion exchange process. Typically, a strong base anion exchanger operating in OH- form is used.
DI Exchange Tanks
DI Bottles, SDI, Service DI, PE, Portable Exchange, PEDI, Exchange Bottles
DI Exchange tanks are leased or rented to a facility that lacks the means to regenerate ion exchange resin.
Effective Size
Mesh Size, Average Size
Effective size is the measured diameter of particles in a media or resin bed. The mesh size that allows 10% of the particles to pass through while retaining the other 90% is the effective size. So 10% of the particles or grains should have a smaller diameter than the remaining 90%.
Boiler Feed water, Makeup Water, Boiler Make up water
Feedwater is water that is intended for treatment and fed into a water treatment system.
GPM, Gallons Per Minute, M3/Hr, Feet per Second
Flowrate is the amount of regenerant or water that passes a specific point in a set amount of time. This measurement is generally given in gpm/sqft of bed area (or L/min). In ion exchangers, flow rate is measured in gpm/cuft of resin. Flow rate is a critical design factor by which the effectiveness of water treatment equipment is measured.
Well water
Groundwater is located beneath the surface of the ground. It is water that seeped into the ground through geological formations and interstitial spaces in the soil.
Hard Water
Water Hardness
Hard water is water that has dissolved compounds of magnesium, calcium, and sometimes other trivalent or divalent metallic compounds. The term “hard water” was originally used to describe water that was “hard” to wash in and wasted soap. Dissolved compounds in hard water cause soap to stop lathering by developing an insoluble curdy precipitate. Hard water is also typically responsible for the buildup of scale in boilers and cooking pans, with dissolved magnesium and calcium being the primary culprits. Water hardness is typically measured in grains per gallon or parts per million (ppm) of calcium carbonate equivalent.
Hydrogen Sulfide
Sulfur, Rotten Egg Smell, Sulphur
Hydrogen Sulfide is a flammable and corrosive gas that is often found in well water. The dissolved gas is typically accompanied by low pH levels and iron. Concentrations of less than one milligram per liter (mg/L) of hydrogen sulfide gives water a musty or swampy odor. Most people can detect the odor of hydrogen sulfide in concentrations as low as 0.5 mg/L. At concentrations higher than one mg/L, water takes on a “rotten egg” smell and becomes corrosive to plumbing.
Makeup Water
Boiler Makeup Water
Makeup water is the treated water that is added to a cooling tower or boiler circuit to replace water lost through steam leaks and/or evaporation.
Mixed Bed
Mixed Bed Resin, Mix Bed,
A mixed bed is a vessel that contains a mix of two or more filter mediums or exchange products during a service run.
A re-bed is the process of completely removing and replacing the resin or media inside a tank. This differs from a “topping off”, which occurs when additional resin is added to replace what has been lost.
Regeneration is the use of a chemical solution, known as a regenerant, to replace the unwanted ions that have been deposited on an ion exchange resin during water treatment. The unwanted ions are flushed and replaced with the ions needed to refresh the capacity of the exchange medium so it can be reused.
Resin, as it pertains to water treatment, refers to ion exchange resin products composed of specially manufactured organic-polymer beads. A resin bed is used in water softening and ion exchange procedures to eliminate dissolved salts from water
A tank is the part of the water treatment system that houses the ion exchange resin or filter media.
Tannins are natural, water soluble, organic phenolic compounds that are formed by the decomposition of vegetation. Tannins are most prevalent in water where large quantities of decayed vegetation are present, and can cause water to turn a faint yellowish to brown color. Tannin molecules generally form anions in water that has a pH greater than 6 and should be treated with anion exchange resins. If the pH is less than 5, activated carbon treatment is recommended.
UV Light
Ultraviolet light, or UV light, is invisible light that has a wavelength between that of visible light (3900 angstroms) and x-rays (100 angstroms). UV light can be used to disinfect water.
Water Softener
A water softener is a piece of water treatment equipment that facilitates the reduction/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 softening or lime-soda softening.

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