Absolute filter rating:
Filter rating meaning that 99.9% (essentially all) of the particles larger than a specified micron rating will be trapped on or within the filter.
Acidity:
The quantitative capacity of a water or solution to neutralize an alkali. Acidity is the opposite of alkalinity. Waters with a pH of lower than 7.0 are considered to be acidic.
Acid Rain:
Rainfall below the natural pH range, caused by contact with atmospheric pollutants such as nitric and sulfuric oxides and carbon monoxide.
Activated Carbon:
A water treatment medium found in block, granulated, or powdered form, which is produced by heating carbonaceous substances (bituminous coal, wood, coconut shell) in the absence of air, creating a highly porous material.
Adsorption:
The physical process occurring when liquids, gases, or suspended matter adhere to the surfaces of, or in the pores of, an adsorbent medium. A physical process occurring without chemical reaction.
Aeration:
The process of adding air to a water supply for the purpose of oxidizing or mixing.
Algae:
Single-celled or simple multi-celled organisms, commonly found in surface water, which produce their own food through photosynthesis. Excessive algae growth may cause the water to have undesirable odors or tastes, and decay of algae can deplete the oxygen in the water.
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. There are three kinds of alkalinity: Carbonate, bicarbonate, and hydroxide alkalinity. Total alkalinity is the sum of all three kinds of alkalinity.
Alum:
The common name for aluminum sulfate, which is often used as a coagulant in water treatment.
Aluminum:
(AI+3, secondary MCL: 0.05-0.2 ppm)
Aluminum silicate is the most abundant mineral in the Earth's crust, and it is almost always a major component of turbidity, dust, mud and silt. In addition, soluble aluminum salts are commonly used in municipal water treatment plant, where they form a solid "floc" That entraps turbidity and makes it easier to filter out. The Secondary MCL for aluminum is not based on its toxicity (which is very low), but rather as an indicator of filter failure. The well-known connection between aluminum plaques in the brain and Alzheimer's disease is now understood to be an effect, not a cause. A concentration of 1.6 ppm is considered extremely high and seldom encountered in drinking water; normal Levels are generally lower that 0.2 ppm. At normal water pH levels, aluminum is particulate in nature and is removed by fine filtration.
Anion:
Negatively charged ion in a solution.
Anion exchange:
An ion exchange process in which anions in solution are exchanged for other anions from an ion exchanger. (Softeners are one type of ion exchanger)
Antimicrobial:
An additive, material, fluid or chemical that inhibits and kills the growth of micro- organisms on contact.
Aquifer:
Natural, underground porous formation where mineral- bearing water flows or is stored. Source of well water.
Arsenic:
(As, MCL: 0.05 ppm; under review)
Arsenic is a notorious poison, and its importance in water has increased greatly in recent years because new estimates of its toxicity suggest that the MCL should be reduced from 50 ppb (0.05 ppm) to the 1-5 ppb (0.001-0.005 ppm) range. Contamination at that low level in water is unfortunately not rare. It can be removed by ion exchange or filtering through activated alumina, but Reverse Osmosis is the usual remedy.
Asbestos:
A fibrous silicate material, chiefly calcium magnesium silicate; a noncombustible, nonconducting, and chemicalresistant material; a known lung carcinogen.
ASME Code:
Used in relation to filter vessels. ASME= American Society of Mechanical Engineers, Boiler and Pressure Vessels. Sections VIII and X apply to pressure vessels.
Backwash:
Reversal of a solution's flow through a filtration system. Often used as a cleansing mechanism in sand and dual- media filters.
Bacteria:
Any of a class of microscopic single- celled organisms reproducing by fission or by spores. Characterized by round, rod -like spiral or filamentous bodies, often aggregated into colonies or mobile by means of flagella. Widely dispersed in soil, water, organic matter, and the bodies of plants and animals. Either autotrophic (self-sustaining, self-generative), saprophytic (derives nutrition from non living organic material already present in the environment), or plastic (deriving nutrition from another living organism). Often symbiotic in man, but sometimes pathogenic.
Bacteriostatic:
Having the ability to inhibit the growth of bacteria without destroying the bacteria. For example: Silver-impregnated activated carbon will reduce bacteria colonization in a filter but not eliminate it.
Bar:
Designation of pressure units. 1 bar = 1 psi ÷ 14.5
Barium
(Ba+2, MCL: 2 ppm)
Ba++ ion is very common in natural waters, but it hardly ever exceeds 1.0 ppm and is not a problem. Chemically it is similar to calcium and is removed by softeners.
Blinding:
In depth and surface filtration, a buildup of particulates on or within the filter, preventing fluid flow through the filter at normal pressures.
Blowdown:
The withdrawal of water containing a high concentration of solids from an evaporating water system (such as a boiler system) in order to maintain the solids-to-water concentration ratio within specified limits. Steamers "blowdown" to eliminate mineral buildup and help prevent scale buildup on surfaces.
Cadmium:
(Cd+2, MCL: 0.005 ppm)
Cadmium is very rare in natural water, generally occurring only as a corrosion by-product of galvanized pipes, because cadmium is a common contaminant of impure zinc. Average levels seldom exceed 0.0004 ppm in drinking water, and levels of 0.005 ppm are seldom encountered.
Calcium (Ca):
(Ca+2, no MCL)
One of the principal elements making up the earth's crust. Calcium compounds, when dissolved, 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. Ca++ ion is the major "hardness" ion (see Total Hardness).
Calcium Carbonate (CaCO3):
A chemical compound found in nature as calcite (in limestone, marble, and chalk) and aragonite (in pearls) and in plant ashes, bones, and many shells.
Cation:
An ion carrying one or more positive charges.
Caustic Soda:
Sodium hydroxide (NaOH), commonly known as lye. A commonly-used chemical in water treatment.
Cellulose:
A fibrous material of vegetable origin used as a filter medium.
Charcoal:
An adsorbent carbon product, which has about one-third the surface area of activated carbon.
Chemical Feeder:
A pump used to meter chemicals such as acid, chlorine or polyphosphate into a feed water supply.
Chloramines:
Chemical complexes formed from the reaction between ammonia and chlorine being used to disinfect many municipal water supplies. Unlike chlorine, chloramines do not combine with organics in the water to form potentially dangerous Trihalomethanes (THM's). Water containing chloramines may not be used for fish tanks or for kidney dialysis application. The proportions of the chloramines depend on the physical and chemical properties of the water.
Chloride:
(C1-, Secondary MCL: 250 ppm)
C1- ion, like Na+, is almost universally present in tap water, but generally at low levels, and it is seldom of any consequence. When both Na+ and C1- are elevated, suspect seawater intrusion. Levels range from 1-250 mg/L in drinking water. A noticeable taste occurs at 250 mg/L. Reverse Osmosis is the only reasonable remedy.
Chlorination:
The addition of small amounts of free chlorine, usually 0.2 to 2.0 ppm, to render water bacteriostatic in a water supply.
Chlorine:
(C12 no MCL)
A gas widely used in the disinfection of water and as an oxidizing agent for organic matter, manganese, iron, and hydrogen sulfide. It is used in the form of Free Chlorine (fast acting) and Combined Chlorine (slow acting). Treatment levels in tap water range from zero or trace to 3 ppm, usually around 0.5 ppm if it is "Free Available Chlorine" (FAC) or around 1 ppm if it is Monochloramine, which is called "combined chlorine". Analysis is best on site; chlorine residuals disappear in transit to a laboratory. Filtration through activated carbon is the preferred remedy for chlorine under normal intermittent flow conditions.
Coagulant:
A material, such as alum, which will form a gelatinous precipitate in water and cause the agglomeration of finely, divided particles into larger particles, which can then be removed by settling and/or filtration.
Coliform bacteria:
A particular group of bacterial primarily found in human and animal intestines and wastes. These bacteria are widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic (disease producing) bacteria.
Colour:
(Secondary MCL: 15 CU)
"Colour" in water means the yellow to brown colour of the tannins, lignins, and humic acids that leach out of decaying wood and other vegetation. These substances are not toxic, but they are the most common source of THMs and other disinfection by-products when chlorinated. A value of 5 units is barely detectable; 300 are like weak tea.
Condensate:
Water obtained through evaporation and subsequent condensation. Normally the water resulting from condensing plant steam originally generated in a boiler. Water condensed in a water still operation is usually called distillate.
Conductivity:
The property of a substance's (in this case, water) ability to transmit electricity. The inverse of resistivity. Measured by a conductivity meter, and described into micro Siemens/cm.
Contact Time:
The length of time an absorbent or adsorbent is in contact with a liquid prior to being removed by the filter or to the occurrence of a chemical change.
Contaminant:
A source of contamination, an impurity. Any substance in water other than H2O.
Copper:
(Cu+ or Cu+2, "Action Level": 1.3 ppm)
Copper occurs as Cu+ and Cu++ ions corroded from copper pipe and fittings of brass (a copper-zinc alloy), and also as organic complexes used to inhibit algae in reservoirs. It is now regulated by controlling the pH, alkalinity and Langelier index so that the water does not corrode plumbing materials to produce copper or lead. Copper drinking water levels hardly ever reach 1.0 ppm and on average are below 0.05 ppm.
Chromium:
(Cr+3, CrO4-2, MCL: 0.1 ppm)
Naturally occurring Cr+++ in water is very unusual and not a problem. However, industrial pollution from metal plating operations used to be common. Drinking water levels on average contain 0.008 ppm or less: levels above 0.03 ppm are considered extremely high.
Cryptosporidium (Crypto):
A waterborne protozoan that forms cysts and causes acute gastrointestinal illness in humans. Cryptosporidium is commonly found in unfiltered surface water and is resistant to disinfectants such as chlorine and ultraviolet light. It can be removed by filtration that captures all particles of one micron and greater in size. (See cysts)
Cyst:
A capsule or protective sac produced about themselves by many protozoans (as well as some bacteria and algae) as preparation for entering a resting or a specialized reproductive stage. Similar to spores, cysts tend to be more resistant to destruction by disinfection. Fortunately, protozoan cysts are typically 2 to 50 microns in diameter and can be removed from water by fine filtration.
Deionization:
Process utilizing specially - manufactured ion exchange resins which remove ionized salts from water. Can theoretically remove 100% of salts. Deionization typically does not remove organics, virus or bacteria, except through "accidental" trapping in the resin and specially- made strong base anion resins which will remove gram - negative bacteria.
Delta P:
The pressure drop or loss (in psi) by flowing water in a pressurized system as the result of the velocity and turbulence of the flowing water, restrictions the water flows through, and roughness of surfaces the water flows past.
Demineralization:
The process of removing minerals from water, usually through deionization, reverse osmosis or distillation.
Dew point:
The temperature to which air must be cooled to cause condensation of the water vapor it contains.
Differential pressure:
The difference in pressure between the upstream and downstream sides of a filter. It can also be the difference in pressure between two points in a system or of a component in such system.
Dirt Capacity:
The weight of a specified artificial contaminant which must be added to the influent to produce a given differential pressure across a filter at specified conditions. Used as an indication of the relative service life.
Disinfectant:
A fluid or gas used to disinfect filters, demineralized water systems, pipe, pipelines, systems, vessels, etc.
Disinfection:
The treatment of water to inactivate, destroy, and/or remove pathogenic (disease producing) bacteria, viruses, cysts, and other microorganisms for the purpose of making water microbiologically safe for human consumption. Disinfection may also be called sterilization.
Dissolved Solids:
The residual material remaining from a filtered source after evaporating the solution to a dry state.
Distillation:
The process of condensing steam from boiling water on a cool surface. Most contaminants do not vaporize and therefore do not pass to the distillate. Removes nearly 100% of all impurities.
Distilled water:
Water which has been cleansed by passing through one or more evaporation-condensation cycles until it contains a very low amount of dissolved solids (usually less than 5.0 ppm TDS).
Efficiency:
The ability, expressed as a percent, of a filter to remove a specified artificial contaminant to a given contaminant concentration under specified test conditions.
Effluent:
The outflow from any water processing system or device.
Exhaustion:
In water softening or ion exchange, the point where the resin can no longer exchange additional ions of the type the process was designed for.
Feed/Feedwater:
The input solution to a treatment/purification system, including the raw water supply prior to any treatment.
Ferric iron:
Small solid iron particles containing trivalent iron, usually as gelatinous ferric oxide which is suspended in water and visible as "rusty water." Ferric iron can normally be removed by filtration. Also called precipitated iron.
Ferrous iron:
A divalent iron ion, usually as ferrous bicarbonate, which when dissolved in water produces a clear solution. It is usually removed by cation exchange water softening or oxidation.
Filter:
A device installed as part of the water system through which water flows for the purpose of removing turbidity, taste, color, iron, or odor. Filters can be loose media beds in tanks or cartridge type devices and filter media may be used for mechanical, adsorptive, neutralizing, or catalyst/oxidation filtration processes.
Filterability:
This is a standard test for the plugging tendency of a water sample. It measures the time it takes to filter 250 mL through a standard 47 mm diameter, 0.45 um membrane filter disc with constant vacuum of 8 psi. Less than 3 minutes is good; 5-10 minutes indicates a need for pre-filtration, 10-15 minutes indicates a high likelihood of plugging finefilters, and 15 minutes or more predicts severe "short life" problems for fine-filters.
Filtrate:
Any liquid that has passed through the filter medium. Sometimes erroneously called effluent. Also known as the clarified effluent from a filter.
Filtration:
The process by which solid particles are separated from a liquid by passing the liquid through a permeable material. Also, the physical or mechanical process of separating insoluble particulate matter from a fluid, such as air or liquid, by passing the fluid through a filter medium that will not let the particulates through.
Filtration Rate:
The volume of liquid that passes through a given area in specified time. Usually expressed as gallons per square foot per minute (or hour).
Floc:
Coagulated groupings of formerly suspended particles which then settle by gravity.
Flocculants:
Chemical(s) which, when added to water, cause suspended particles to coagulate into larger groupings (flocs) which then settle by gravity.
Flocculation:
The process of agglomerating particles into larger groupings called flocs, which then settle by gravity.
Fluoride:
(F-, MCL: 14 ppm)
The F- ion is hardly ever found in natural water, but is intentionally added by most waterworks to inhibit tooth decay. Allowed concentrations are 1-4 mg/L-1 ppm where the climate is hot and a lot of water is consumed, and 4 ppm where it is cooler and people do not drink so much water. Unwanted fluoride can be removed by reverse osmosis or filtration through activated alumina.
FTU:
Formazine Turbidity Units - a measure of turbidity, by a nephelometer.
Giardia lamblia:
A type of cyst found in the intestines of mammals and in water contaminated by mammal droppings. The Giardia lamblia cyst, which is common and frequently carried in water, is capable of causing a contagious waterborne disease characterized by acute diarrhea. This disease is sometimes called beaver fever. Giardia is resistant to chlorine and ultraviolet light. It can be removed by filters that capture all particles of four microns and greater in size.
Grains Per Gallon:
A common method of reporting water analysis in the United States and Canada. One grain per gallon equals 17.1 parts per million (ppm) or 17.1 milligrams per liter.
Groundwater:
Water confined in permeable sand layers or cavities between rock and clay. All subsurface water.
gpg: Grains per gallon
gpm: Gallons per minute
Grain:
A unit of weight equal to 0.0648 grams or 0.000143 pounds or 1/7000th of a pound.
Hardness:
A common quality of water that contains dissolved compounds of calcium and magnesium and, sometimes, other divalent and trivalent metallic elements. Hardness prevents soap from lathering by causing the development of an insoluble precipitate in the water; hardness typically causes the buildup of hardness scale (such as seen in cooking pots and pans), Dissolved calcium and magnesium salts are primarily responsible for most scaling in pipes, boilers, and water heaters, and cause numerous problems in the laundry, kitchen, and bath. Hardness us usually expressed in grains per gallon or (or ppm) as calcium carbonate equivalent. The degree of hardness standard as established by the American Agricultural Society of Engineers (S-369) and the Water Quality Association (WQA) is:
Term Grains/gallon Mg/Liter (ppm)
Soft = Less than 1.0 Less than 17.1
Slightly Hard = 1.0 to 3.5 17.1 to 60
Moderately Hard = 3.5 to 7.0 60 to 120
Hard = 7.0 to 10 120 to 180
Very Hard = 10.5 and above 180 and above
Heavy Metals:
Metals having a high density of specific gravity approximately 5.0 or higher. The elemental weight is also high. A generic term used to describe contaminants such as calcium, lead, and mercury. In low concentrations most are toxic to humans.
High Purity Water:
Highly treated water with attention to microbiological reduction or elimination; the term commonly used in the pharmaceutical industry.
Hydraulic:
Referring to water or other fluids in motion
Hydrogen Sulfide:
A corrosive and flammable gas often found dissolved in well water and often accompanied by iron and low pH values. Hydrogen sulfide develops from decaying organic matter, from sulfate-reducing bacteria and from petroleum refining. A very disagreeable "rotten egg" odor is characteristic of the presence of hydrogen sulfide. May be oxidized and filtered.
Influent:
The stream of water to be treated as it flows into any kind of water treatment unit or device, such as hard water into a softener or turbid water into a filter.
Ion:
An atom or radical (group of atoms) which carries an electrical charge as the result of having lost or gained electrons. Positively charged ions are called cations; negatively charged ions are called anions.
Ion Exchange:
A process in which ions are preferentially based on equilibrium, adsorbed from a solution for equivalently charged
ions attached to small solid structures called resin.
Iron:
(Fe+2, Fe+3, secondary MCL: 0.2 ppm)
Iron in water is harmless, but it causes a metallic taste and contributes to colour, turbidity, and scaling. When it is in reduced form, called "ferrous" iron (Fe++), it is fully soluble and produces its characteristic taste and rust stains at concentrations as low as 0.2 ppm. When it is oxidized to Fe++ (ferric iron") by chlorine or other disinfectants, or even by ordinary dissolved oxygen, it immediately precipitates as a rust-coloured particle also known as "iron floc". This is a gooey material, which is readily incorporated into scale and can clog filters quickly when present at levels above 0.2 ppm. When iron is present at the same time as sulfide (see sulfide), black iron sulfide is formed. When present along with tannins and lignins (see "Colour"), they combine to form an organic complex known as "heme iron", which is difficult to remove. Most drinking water supplies contain iron levels below 0.2 ppm levels up to 1.0 ppm are considered high, levels from 1.0 ppm to 5.0 ppm which are extremely high are not often found. The most common remedy is simple filtration. Coarse profilers do well and are recommended to extend the life of fine-filters. If the water is not chlorinated, che ical oxidation must precede filtration.
Iron bacteria:
Bacteria which thrive on iron and are able to actually use ferrous iron (as found in water or steel pipes) in their metabolic processes, to incorporate ferric iron in their cell structure, and to deposit gelatinous (slimy) ferric hydroxide iron compounds in their life processes. Iron bacteria can cause plugging, staining, and taste and odor problems in foodservice water applications.
Langelier Index Value:
The LI is a mathematical estimation of the chemical tendency of water to deposit or to dissolve lime scale (calcium carbonate, CaCO3). It is equal to the actual, measured pH of the water minus the calculated pH at which the water would be saturated with calcium carbonate. A negative value indicates an inability to form scale or a tendency to dissolve scale; a positive value predicts a problem with deposition of lime scale. A value of 0 to + 0.5, a slight scaling tendency; 0.5 to 1.0, moderate; 1.0 to 1.5 heavy scale; and 1.5 to 2.0 and above, severe.
Lead:
Serious lead poisoning is almost always due to ingestion of paint chips or breathing the dust, but low-level poisoning is more insidious, and that is often traced to drinking water. It occurs as particles of lead oxide or carbonate and as ordinary Pb++ ion, all derived from corrosion of plumbing materials containing lead. These include lead pipes, lead service connections, lead-based solder for joining copper pipe, and various fittings and faucets made of brass containing lead. Levels in potable water are limited by treatment to no greater that 15 ppb (0.015 ppm). Drinking water levels of lead on average seldom exceed .004 ppm (4 ppb). Lead can be removed or reduced in several ways. When the pH is moderate or high and the water has at least 50 ppm of alkalinity, virtually all lead will be in particle form that will be removed by any fine-filter. Activated carbon has modest capacity for adsorbing lead; so most large carbon filters with significant organic chemical reduction capability can be relied on to remove lead as well. Lead also absorbs onto activated alumina, "bone char," and other specialty absorbents, which are used in filters.
Lime scale:
Hard water scale formed in pipes and vessels (generally more severe on the hot water side) containing a high percentage of calcium carbonate (CaCO3) or magnesium carbonate (MgCO3). Becomes particularly troublesome in cooking steamers, coffee equipment, and ice making equipment in foodservice applications as scale forms on heating elements, boiler casings, and evaporators.
Magnesium:
(Mg+2, no MCL)
Mg++ ion is one of the major "hardness" ions (see Total Hardness), dissolved from dolomite mineral in soil and limestone, usually found at a level one-third to one-half that of the calcium ion in water.
Manganese:
(Mn+2, secondary MCL: 0.05 ppm by itself, 0.3 ppm Fe + Mn) When Mn++ ion occurs in water, it is usually associated with iron, causing the stains, etc. to be black instead of rustred. At one time, manganese had its own Secondary MCL of 0.05 ppm; now, it is just lumped in with iron for a limit of 0.3 ppm Fe + Mn. Levels in drinking water supplies are at or below 0.03 ppm Mn; levels up to 0.5 are considered very high; levels from 0.5 to 2.5 ppm are extremely high; and levels above 2.5 are rare. Remedies are the same as for iron.
Media:
The material that performs the actual separation of solids from liquids. Sometimes erroneously used to mean septum.
Media Migration:
Release of filtration media particles into the effluent of the filter.
Medium:
The porous material that performs the actual process of filtration. The plural of this word is "media."
Membrane:
(Polymeric). High engineered polymer film containing controlled distribution of pores. Membranes serve as a barrier permitting the passage of materials only up to a certain size, shape, or character. Membranes are used as the separation mechanism in reverse osmosis, electro dialysis, ultra filtration, Nanofiltration, and micro filtration, as disc filters in laboratories, such as pleated final filter cartridges, particularly in pharmaceutical and electronic applications.
Mesh:
Number of strands in a linear inch of woven filter fabric, usually wire. It is also used as a septum.
MCL:
The Maximum Contaminant Level is the official, legal limit for that parameter, established by the U.S. EPA and adopted by the State health or environmental agencies. "Primary" MCLs are mandatory limits for health reasons, and "secondary" MCLs are recommended limits for aesthetic (taste) reasons.
Mg/L:
Milligrams per liter is the most common unit of concentration, and it is essentially equivalent to "parts per million" or ppm. That is because water has a density of 1 g/mL when pure. Thus, a liter of water weighs a million mg, 1 mg/L = 1ppm.
Micron:
A metric unit of length equal to one millionth of a meter or one thousandth of a millimeter, or about 0.00003937 inches.
Micron rating:
A measurement applied to filters or filter media to indicate the particle size at which suspended solids above that size will be removed. As used in the water treatment industry, this may be an absolute or a nominal rating.
Microorganism:
A living organism invisible or barely visible to the naked eye and generally observable only through a microscope. Also called a microbe. Microorganisms are generally considered to include algae, bacteria, fungi, protozoa, and viruses.
Mineral water:
Water that is naturally or artificially impregnated with mineral salts or gases (carbon dioxide). The term also designated bottled water that contains no less than 250ppm total dissolved solids (TDS) and originates from a groundwater source.
Mixed Bed:
An ion exchange tank consisting of both cation and anion resin mixed together. Provides the most complete deionization of water, up to 18.3 megohn/cm resistivity. Commonly used to polish water already treated by two - bed ion exchange tanks or reverse osmosis.
Module:
A membrane element combined with the membrane element housing.
Molecule:
The smallest physical unit of a compound or chemical, composed of one or more atoms, which retains the properties of that substance.
