Water Glossary


Adsorption – A process that causes contaminates to separate from the water molecules and bond to the filter media. 

Acid – A substance that when dissolved in water releases hydrogen ions. It has the ability to react with bases to form salt. Acidic water is characterized by a sour taste, and turns a litmus paper red.

Acidity – A condition of water when the pH is below 7.0.

Activated Carbon – A granular material, usually made from wood or coconut shell, which is roasted at high temperature in the absence of air. Activated carbon has a very porous structure, and is used as an adsorbent in water conditioning. Commonly used for reducing many types of chemicals such as chlorine, and for removing organic compounds from water.

AgION – An antimicrobial compound that inhibits the growth of bacteria. The active ingredient is silver, a natural antimicrobial metal ion.

Alkali – Also called a base, alkali is the opposite of an acid. An alkali has a pH above 7.0 and is characterized by a bitter taste. Examples include carbonate and bicarbonate salts of calcium, magnesium, potassium, and sodium.

Alkalinity – A condition of water when the pH is above 7.0. It is the capacity of a water to neutralize an acid.

Anion – A negatively charged ion in solution. Examples include chloride, nitrate and sulphate.


Bacteria – Tiny, one-celled organisms found in water that break down organic matter. Not all bacteria is harmful, but some can cause health problems. Chlorine or chloramine is typically added to municipal water supplies to kill bacteria. Bacteria can sometimes grow inside carbon filter canisters, due to the dark, wet environment. This can cause bio-film to develop on the filter media, reducing the filter’s effectiveness and shortening its life.

Bacteriostatic – An environment where bacteria is unable to grow and reproduce. Silver is sometimes added to carbon filters to achieve this effect. A bacteriostatic filter does not actually kill the bacteria, but prevents its growth.

Biofilm – As bacteria grows and reproduces within a filter canister, it can over time create a slime film that adheres to the filter media. This film can clog the pores of the carbon, thus reducing its ability to filter.

Buffer – A solution that helps to maintain the pH in water.


Calcium (Ca) – Dissolved calcium compounds are a major factor in making water hard, and causing the formation of scale.

Cation – A positively charged ion in solution. Examples include sodium and calcium.

Cation Exchange – A common process for reducing hardness in water. A synthetic resin is coated with positively charged sodium ions. When water containing dissolved, negatively charged cations (calcium and magnesium ions that cause the water hardness) meets the resin, the sodium ions are exchanged with the cations.

Chemical Filtration – A carbon filter with millions of tiny pores that adsorb chemicals such as chlorine.

Chloramine – A combination of chlorine and a small amount of ammonia, chloramine is a disinfectant used by some water utilities. The addition of the ammonia helps to make the solution more stable and longer lasting. Chloramines can cause an adverse effect on the taste and odour of water.

Chloride – Chloride is a salt that is highly soluble in water. It can cause corrosion on plumbing pipes and pitting corrosion on stainless steel. At high levels it imparts a salty taste to food and beverages. Public Drinking Water Standards require chloride levels not to exceed 250 mg/L

Chlorine – Chlorine is chemical used by many water utilities for the disinfection of water and as an oxidizing agent for organic matter and some metals. It imparts a noticeable taste and odour to water, and may contribute to form trihalomethanes (THM). When chlorine is introduced into water, a portion of it may bond with contaminants such as oils and organic matter and become “combined chlorine”. Another form of combined chlorine is chloramine, which some municipalities use instead of chlorine for disinfection. Chloramine is chlorine combined with ammonia. The chlorine that does not bond remains as residual Free Chlorine. Total chlorine is a total of both combined chlorine and free chlorine.

Colour – A tint that is usually caused by dissolved organic matter (often fulvic and humic acids). It cannot be removed by mechanical filtration. (Colour is different than turbidity, which is cloudiness in water.)

Cryptosporidium – A group of common waterborne intestinal parasites usually found in water contaminated by animal waste. It causes illness, and can sometimes be fatal to individuals with weakened immune systems. Cryptosporidium is resistant to chlorine disinfection, but can be removed from water with fine filtration.

Cyst – A parasite that develops a hard protective shell when it leaves its host. This shell makes them strongly resilient, capable of surviving chlorine disinfection. When a cyst is ingested, it can cause intestinal illness, including diarrhoea, abdominal pain, cramps and nausea. Cysts can be removed from water by fine filtration. Examples of cysts include Cryptosporidia and Giardia.


Giardia Lamblia – A common water-borne protozoan parasite that can cause severe intestinal illness (also known as Beaver Fever) when ingested. Outside of its host, it becomes a cyst that is resistant to chlorine. Giardia can be removed by fine filtration.

GPM – Gallons per Minute

Grains – A unit of weight equal to 1/7000th of a pound that is used to measure the hardness of water and the capacity of a water softener.


Hard Water – Water containing high levels of dissolved calcium, and lesser amounts of magnesium, typically found in limestone areas. It is often expressed as grains of hardness per gallon of water. Hard water produces scale when heated, which has been known to clog foodservice equipment such as coffee brewers and steamers.

Hydrogen Sulphide (H2S) – A toxic, colourless gas produced naturally during decomposition of organic material that contains sulphur. It has an odour similar to rotten eggs, and can be corrosive.


Ion Exchange – Hard water has calcium and magnesium ions present, and ion exchange removes these from water by replacing them with non-hardness ions. Water softeners use an insoluble resin, which is saturated with sodium. As hard water comes in contact with this sodium-coated resin, the calcium and magnesium ions attach to the resin, and the sodium is released. The hardness is now removed from the water. The resin is flushed with a salt brine solution, and the sodium again attaches to the resin. The calcium and magnesium ions are released, and are flushed out with waste water.

Ion Exchange Resin – See Resin.

Iron – Iron in water can be either ferrous (dissolved) or ferric (oxidized particles), and can creates red-orange staining on plumbing. Certain types of bacteria can feed off iron, and create slime that can clog plumbing.


Lime Scale – See Scale.


Magnesium (Mg) – Magnesium is a common element making up the earth’s crust. When dissolved in water along with calcium, the result is hard water. When energy is applied to hard water, the dissolved magnesium and calcium become hard deposits called scale. Scale can clog foodservice equipment such as coffee brewers and steam equipment.

Membrane – A thin layer of microporous, semipermeable material that allows water to pass through, but not particles that are too large to fit through the pores. Membranes can filter substances from 5 microns to as small as .02 microns, depending on its classification. 

Media – A fine material used in filters to allow the passage of water, but not certain particles or molecules that are suspended in the water. Ion exchange resin is also called a media.

Mechanical Filtration – A filtration process by which water is driven through a media, and the media prevents suspended solids from passing through. The density of the media determines the micron rating. A fine filter can stop particles as small as .5 micron, while a course filter might stop particles of >5 microns.

Methyl Tertiary Butyl Ether (MTBE) – A chemical oxygenate that is added to gasoline to help it burn cleaner. It is easily dissolved in water, and can enter water sources through leaking underground storage tanks and pipelines. According to the EPA, there is insufficient data at this time to determine the health effects of MTBE in small doses, but in large doses is it a potential human carcinogen.

Micron – A unit of measurement equal to one millionth of a meter, 1/25,000 of an inch. A high-grade filter can remove solids from water as small as .5 micron.


NSF – A not-for-profit organization that is the world leader in standards development, product certification, education, and risk-management for public health and safety. NSF develops national standards, focusing on food, water, indoor air, and the environment

Particulate – Solids suspended in water.


pH – Water has both dissolved alkaline and acid. When there is equal amounts of both, the water has a pH of 7 and is considered neutral. Water with a pH of less than 7 is considered acidic. Too much acidity can be corrosive on equipment, discolour water and create an off-taste.

Point of Entry (POE) – A device generally consisting of multiple carbon-filled vessels that supply filtered ingredient water to multiple water using appliances such as a coffee brewers, fountain dispensers, ice machines, warewashing equipment and steamers.

Point of Use (POU) – A device generally consisting of one or more carbon-filled vessels that supply filtered ingredient water to single water using appliances such as a coffee brewers, fountain dispensers, ice machines, warewashing equipment and steamers.

Ppb – Parts per billion

Ppm – Parts per million

Prefilter – A coarse filter that is used to capture sediment and particles of >5 microns. A prefilter is typically placed before fine filtration to extend the life of the fine filters.


Resin – An insoluble permanent medium used in water softeners as part of the ion exchange process. Resin is usually polymer beads.

Reverse Osmosis – A process for purifying water that uses pressure to force water through a semipermeable membrane. This leaves behind the dissolved minerals (see TDS), which are then carried out with waste water. Often, mechanical and/or chemical filters are installed before a reverse osmosis system to improve taste and odor of the water.


Scale – Water with high concentrations of calcium and magnesium, when heated, revert back to rock. This can cause a hard crust to form on foodservice equipment such as ice machines, coffee brewers, espresso machines and steamers. Over time it can reduce the efficiency and damage the equipment. Also called “limescale”.

Submicron Filter – A fine membrane filter used to remove particulates of less than one micron in size.


Total Dissolved Solids (TDS) – A measure of the quantity of dissolved minerals in water. High levels of TDS usually requires a reverse osmosis system to remove.

Trihalomethanes (THM) – When chlorine is used to disinfect water it can sometimes react with natural organic matter to create THM’s, a volatile organic chemical. According to the EPA, drinking water contaminated with THM’s over many years may cause health problems including cancer.

Turbidity – Fine, suspended solids can cause the water to become cloudy. The opaqueness of the water is called turbidity, and is measured by the amount of scattering and absorption of light (in nephelometric turbidity units, or NTU). Drinking water should be less than 0.5 NTU.


Virus – The smallest living organism, often less than .02 micron (about 100 times smaller than bacteria), viruses are a parasite that can cause diseases in humans.

VOC (Volatile Organic Chemicals) – Organic chemicals that are found in many common products such as paints, fuels and solvents. VOC’s evaporate easily. Water that is contaminated with high levels of VOC’s is believed to cause a number of serious health problems.