Here is our handy glossary of water to help you with the various terms you may have come across when looking into water treatment solutions. 

Activated Carbon

A type of filter that uses a bed of carbon to remove contaminants and impurities, using chemical adsorption


Something that is made up of water.


A high concentration of salt in water.

Boiling Point

The temperature at which water boils (100 degrees Celsius)


A water purification process in which chlorine is added to water to disinfect and control present microorganisms.


The clearness of a liquid


Two or more different elements held together in fixed proportions by attractive forces called chemical bonds.


The totality of different substances that are left behind in a filter medium after filtration.


The presence of an undesirable substance which pollutes the water.


A natural or artificial channel through which fluids may be transported.


Ability of water to dissolve or break down certain substances, particularly metals.

Cross flow filtration

A process that uses opposite flows across a membrane surface to minimize particle build-up.


The removal of fluoride from drinking water.


Processes to remove minerals from water.


A water-soluble cleansing agent.


The process during which solid particles mix molecule by molecule with a liquid and appear to become part of the liquid.


Water treatment method where water is boiled to steam and condensed in a separate reservoir. Contaminants with higher boiling points than water do not vaporize and remain in the boiling flask.


Substance that dissociates into ions when it dissolves in water.


The building blocks of matter that make up every material substance.


The wearing away of the land surface by wind, water, ice or other geological agents.


The process of changing water from liquid to vapour.

Filter medium

The permeable material that separates solids from liquids passing through it.


A liquid that has passed through the filter medium.


Separation of a solid and a liquid by using a porous substance that only lets the liquid pass through.


The discharge rate of a resource, as a volume over a certain period of time.


The change of a liquid into a solid as temperature decreases (0 degrees Celsius for water)


A microorganism that is commonly found in untreated surface water and can be removed by filtration.


Water that can be found in the saturated zone of the soil.

Hard water

Hard water is water that contains high levels of the minerals calcium and magnesium.

Heat exchanger

A component that is used to remove heat from or add heat to a liquid.

Heavy metals

Metals that have a density of 5.0 or higher and a high elemental weight. Most are toxic to humans, even in low concentrations.


Adding water vapour to air.

Hydrologic cycle

The natural cycle of water passing through the environment, including evaporation, condensation, retention and run-off.


The solid form of water.


Not easily penetrated by water.


Particles or other objects that cause water to be unclear.

Indicator organisms

Microorganisms, such as coliforms, whose presence is indicative for pollution or for the presence of more harmful microorganisms.


An atom in a solution that is charged, either positively (cations) or negatively (anions).

Ion exchange

The replacement of undesirable ions with a certain charge by desirable ions of the same charge in a solution, by an ion-permeable absorbent.

Kinetic Energy

Energy possessed by moving water.


A chalky substance formed by combining calcium and magnesium with heat.


A state of matter, neither gas nor solid, that flows and takes the shape of its container.


The change of a solid into a liquid.


A semi-permeable skin that allows some compounds or liquids to pass through but not others.


A unit to describe a measure of length, equal to one millionth of a metre.


Organisms that are so small that they can only be observed through a microscope, for instance bacteria, fungi or yeasts.

Mineral Water

Water containing large amounts of dissolved minerals such as calcium, sodium, magnesium, and iron.


Combinations of two or more atoms of the same or different elements held together by chemical bonds.


Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals or infective agents.


The process where water molecules pass through membranes naturally, to the side with the highest concentration of dissolved impurities.

Particle size

The sizes of a particle, determined by the smallest dimension, for instance a diameter. It is usually expressed in micron measurements.


The ability of a medium to pass a fluid under pressure.


A contaminant at a concentration high enough to endanger the life of organisms.


Processes used to reduce or eliminate wastewater pollutants from before they are discharged.

Qualitative water assessment

Analyses of water used to describe the characteristics or water.

Quantitative water assessment

Analyses of water properties and concentrations of compounds and contaminants in order to define water quality.


A natural or artificial holding area used to store water.


The dry solids remaining after the evaporation of a sample of water or sludge.

Reverse Osmosis

Reverse Osmosis is a process which uses pressure across a semi-permeable membrane to separate and remove dissolved solids, organics, pyrogens, submicron colloidal matter, viruses, and bacteria from water.

Safe water

Water that does not contain harmful bacteria, toxic materials, or chemicals, and is considered safe for drinking.


A medium that allows water to pass through, but rejects dissolved solids, so that it can be used to separate solids from water.


Waste fluid in a sewer system.


The removal of calcium and magnesium from water to reduce hardness.

Soft water

Any water that does not contain large concentrations of the dissolved minerals calcium or magnesium.

Surface water

All water naturally open to the atmosphere, such as rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries and wetlands.


The gaseous phase of substances such as water.


Conversion of a liquid into vapour.


The smallest life forms known, that are not cellular in nature. They live inside the cells of animals, plants and bacteria and often cause disease.

Water pollution

The presence in water of enough harmful or objectionable material to damage water quality.

Water quality

The condition of water with respect to the amount of impurities in it.

Water supply system

The collection, treatment, storage, and distribution of water from source to consumer.