Pressure that can cause water to backflow into the water supply when a user’s waste water system is at a higher pressure than the public system.

Reverse seepage of water in a distribution system.

Reversing the flow of water back through the filter media to remove entrapped solids.

Microscopically small single-cell organisms, that reproduce by fission of spores.

The introduction of unwanted bacteria into a water body.

An alkaline substance that has a pH that exceeds 7.5.

Sediment particles resting on or near the channel bottom that are pushed or rolled along by the flow of water.

The lower region of a body of water including the bottom.

Salts containing the anion HCO3-. When acid is added, this ion breaks into H2O and CO2, and acts as a buffer.

Chemicals that hold short fibres together in a cartridge filter.

The increase in concentration of a substance in living organisms, as they take in contaminated air, water, or food, due to slow metabolization and excretion.

The amount of oxygen (measured in mg/L) that is required for the decomposition of organic matter by single-cell organisms, under test conditions. It is used to measure the amount of organic pollution in wastewater.

A chemical that is toxic to microrganisms. Biocides are often used to eliminate bacteria and other single-cell organisms from water.

Pollutants that are capable of decomposing under natural conditions.

Population of various microrganisms, trapped in a layer of slime and excretion products, attached to a surface.

Living organisms such as viruses, bacteria, fungi, and mammal and bird antigens that can cause harmful health effects to humans.

Activated carbon that supports active microbial growth, in order to aid in the degradation of organics that have been absorbed on its surface and in its pores.

Decomposition of complex organic materials by microrganisms through oxidation.

The use of living organisms to test the suitability of effluents for discharge into receiving waters and to test the quality of such waters downstream from the discharge.

The biological treatment of wastewater and sludge, by inducing the breakdown of organics and hydrocarbons to carbon dioxide and water.

All living organisms in a region or ecosystem.

Conversion of a substance into other compounds by organisms; including biodegradation.

Water that contains waste of humans, animals or food.

Any place on a filter medium where fluids cannot flow through.

A build-up of particles in a filter medium, that prevents fluids from flowing through.

The amount of dissolved oxygen consumed in five days by bacteria that perform biological degradation of organic matter.

The temperature at which the vapour pressure of a liquid equals the pressure of its surface. The liquid will than vaporize If the pressure of the liquid varies, the actual boiling point varies. For water the boiling point is 100 degrees Celsius.

Water that is sold in plastic containers for drinking water and/ or domestic use.

Water that is neither falls in the category of salt water, nor in the category of fresh water. It holds the middle between either one of the categories.

Addition of chlorine to water until there is enough chlorine present for disinfection of water.

Crack or break in a filter bed that allows the passage of floc or particulate matter through a filter.

Highly salty and heavily mineralised water, containing heavy metal and organic contaminants.

A substance that reacts with hydrogen or hydroxyl ions in a solution, in order to prevent a change in pH.