Glossary of Water Terms

Absolute: Used in reference to filters, for the micron rating of the cartridge indicating that all particles larger than a specified size will be trapped within or on the filter and will not pass through the cartridge.

Absorption: The process of taking up a substance into the physical structure of a liquid or solid by physical or chemical action, but without chemical reaction.

Activated Carbon: A granular material generally produced by carbonizing a cellulose base substance, such as wood or coconut shell in the absence of air. Used to remove tastes, odor, chlorine and organics from water. Adsorption: The process by which molecules, colloids, or particles adhere to the surface by physical action without chemical reaction.

Alkalinity: Capacity for neutralizing acid, usually due to presence of bicarbonate or carbonate ions. Hydroxide, borate, silicate or phosphate ions may contribute to alkalinity in treated water.

Antimicrobial: An additive, material, fluid or chemical that inhibits and kills the growth of micro-organisms on contact.

Backwash: Reversal of a solution's flow through a filtration system. Often used as a cleaning mechanism in sediment filters.

Bacteria: Any of a class of microscopic single-celled organisms reproduced by fission or 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.

Bactericide: Agent capable of destroying bacteria.

Bacteriostat: Substance that inhibits bacterial growth and metabolism but does not necessarily kill the cell. A filtration system that claims bacteriostatic means that the system limits the growth of bacteria, the population of bacteria in the product water is no greater than that of the incoming water.

Carbon Block: Activated carbon powder mixed with chemical binders to form a hard block of carbon. The fine powder used in making carbon blocks increases the adsorption efficiency. Carbon blocks are used for reduction of VOC and some heavy metals.

Chlorine: Disinfectant which eliminates bacteria and is added to most municipal water systems. Chlorine may provide undesirable taste and odor in drinking water. The actual health danger comes from some of the chemical compounds chlorine forms by combining with organic molecules that can be found in water.

Colloid: A substance of very fine particle size, typically between 0.1 and 0..001 microns in diameter suspended in liquid.

Contact Time: The length of time an absorbent is in contact with a liquid prior to being removed by the filter or to the occurrence of chemical change.

Cryptosporidium: Sometimes referred to as Crypto for short, is a waterborne parasite that causes severe stomach cramping, fever, vomiting and diarrhea that can last from10 to 14 days in a healthy persons. Crypto can be found in virtually any contaminated surface water. Very fine filtration of 1 micron and below is effective in removing crypto from the water supply.

Deionization: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure. Hydrogen and hydroxide ions introduced in the process unite to form water molecules.

Demineralization: The removal of all ionized inorganic minerals and salts (not organic materials) from a solution by a two-phase ion exchange procedure.

Disinfection: A process in which pathogenic (disease producing bacteria are killed) may involve disinfecting agent such as chlorine, ultraviolet light, other chemicals or a physical process such as boiling.

Dissolved Solids: The residual material remaining from a filtered source after evaporating the solution to a dry state.

Effluent: The output stream exiting a filtration or water treatment system.

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.

Filter: Specifically a device or system for removal of solid particles (suspended solids). In general, this includes mechanical, adsorptive, oxidizing and neutralizing filters.

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 matter from fluid, by passing the fluid through a filter medium that will not let the particulates through.

Flocculent: Chemicals that when added to water, causes suspended particles to coagulate into larger groupings which then settle by gravity.

Giardia Cysts: A parasite found in water. Very detrimental to the digestive system, causing diarrhea and stomach cramps. Giardia is resistant to chlorine disinfection in water supplies. Very fine filtration of 1 micron and below is effective in removing crypto from the water supply.

GPD: Gallons Per Day.

Groundwater: Water confined in permeable sand layers or cavities between rock and clay. All subsurface water.

Hardness: A characteristic of natural water due to the presence of dissolved calcium and magnesium. Water hardness is responsible for most scale formation in pipes and water heaters and form build-up on kitchen and bath fixtures.

Heavy Metals: Metals having a high density or specific gravity of 5.0 or higher. The elemental weight is also high. A generic term used to describe contaminants such as cadmium, lead and mercury. In low concentrations most are toxic to humans.

Hydrogen Sulfide: A toxic gas (H2S) that is detectable by strong "rotten egg" odor. It is an acid that can cause rapid corrosion of all types of plumbing materials. The effective remedy is chemical oxidation followed by filtration.

Hydrophilic: Water accepting.

Hydrophobic: Water rejecting.

Influent: The fluid entering the filter or water treatment system.

Ion Exchange: A process in which ions are preferentially based on equilibrium, adsorbed from a solution for equivalently charged ions attached to small solid structure called resin. Most water softeners work on this principle.

Media: The material that performs the actual separation of solids from liquid.

Membrane: Generally made of polymeric material, a membrane is a highly 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 and UltraFiltration systems.

Mgl/L: Milligrams of an element per liter of water; approximately equal to ppm (parts per million).

Microfiltration (MF): Filtration designed to remove particles and bacteria in the range of 0.1 to 3 microns in diameter.

Micron: A linear measure equal to one millionth of a meter or 0.00003937 inches. The symbol for the micron is the Greek letter.

Micron Rating: The term applied to a filter or filter medium to indicate the particles size above which all suspended solids will be removed throughout the rated capacity. As used in industry standards, this is a nominal rating as opposed to an “absolute” rating.

Nominal: With regard to the micron rating of cartridge filters, refers to an approximate size particle, the vast majority of which will not pass through the filter. A small amount of particles this size or larger may pass through the filter.

Organic Matter: Substances of/or derived from plant or animal matter as opposed to in- organic matter derived from rocks and minerals. Organic matter is characterized by its carbon-hydrogen structure.

Oxidation: Process by which electrons are lost to an oxidizing agent in order to increase a molecule or ion in positive valence.

Oxidizing Filters: Filters that use a catalytic medium such as manganese oxide to oxidize iron and manganese and then filter the impurities from the water after they have been oxidized.

Parts per million: A common basis for reporting the results of water and waste water analysis indicating the number of parts by weight of a dissolved or suspended constituent-per million parts by weight or water or other solvent.

pH: pH is an expression of hydrogen ion concentration; specifically, the negative logarithm of the hydrogen ion concentration. The range is from 0 to 14, with 7 as neutral, 0 to 7 as acidic and 7 to 14 as alkaline. If the water is acidic the risk of lead and other metals in the water goes up. If the water is alkaline it will have a greater tendency for scale to form.

Pore: An opening in a membrane or filter matrix.

Porous: The ability of certain substances to pass fluids due to an open physical structure.

ppb: Parts per billion, commonly considered equivalent to micrograms per liter.

ppm: Parts per million, commonly considered equivalent to milligrams per liter.

Reverse Osmosis (RO): RO systems use pressure to force water molecules through a membrane, causing contaminants to be left behind and separated from the water. These systems are very effective, especially for removal of heavy metals, nitrate and fluoride but they are more expensive both in terms of equipment, maintenance cost and water usage than other systems.

Scaling: The build-up of precipitated salts on such surfaces as pipes, tanks and boiler condensate tubes.

Softening: Water softeners condition the water through an ion exchange process. A softener exchanges sodium ions for calcium and magnesium ions. Softeners are primarily used to reduce the mineral content in water to prevent scale build-up.

Suspended Solids (SS): Solid organic and inorganic particles that are held in suspension in a solution.

THM: Trihalogenated Methane Compound, initiated by contact between free chlorine and certain organics to form materials similar to certain organic solvents. THM's are toxic and many are considered to be a carcinogen.

TSS: Total suspended solids, the residual matter which can be removed from a solution by filtration. Turbidity: A measure of the amount of finely divided suspended matter in water. A suspension of fine particles in water that causes cloudiness and will not readily settle due to small particle size.

Ultraviolet (UV): Radiation having a wave length shorter than visible light but no longer that X rays. Ultraviolet light with a wave length of 254 nm is used to kill bacteria.

Virus: Any of a large group of submicroscopic infective agents capable of growth and multiplication only in living cells of a host.

VOC: Volatile Organic Compound; synthetic organic compounds suspected to be carcinogens. They include some of the most common and widely distributed water contaminants. Examples include pesticides, herbicides or insecticides that seep into the ground. VOCs are usually the result of pollution and originate from areas of industry.

Water Quality Association (WQA): WQA is an independent non-profit organization that provides the water treatment industry with quality assurances. WQA awards their GOLD SEAL to only water treatment products that have been tested to meet or exceed industry standards for performance, capacity and integrity in removing a variety of water supply contaminants.