Untreated wastewater and its contents.

Intake water before any treatment or use.

Renewing air supplies in the lower layers of a reservoir in order to raise oxygen levels.

Process in which carbon dioxide is bubbled into treatment water in order to lower the pH.

A river, lake, ocean, stream or other watercourse into which wastewater or treated effluent is discharged.

An area where rainwater soaks through the ground to reach an aquifer.

Recycling water after it is used. Often it has to pass a wastewater purification system before it can be reused.

Shortened term for reduction/ oxidation reactions. Redox reactions are a series of reactions of substances in which electron transfer takes place. The substance that gains electrons is called oxidising agent.

A chemical reaction in which ions gain electrons to reduce their positive valence.

Putting the desired counter-ion back on the ion exchanger, by displacing an ion of higher affinity with one of lower affinity.

Extra treatment capacity built into wastewater treatment plants and sewers to be able to catch up with future flow increases due to population growth.

A natural or artificial holding area used to store water.

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

The breaking of an emulsion into its individual components.

The Reversed Osmosis (RO) process uses a semi-permeable membrane to separate and remove dissolved solids, organics, pyrogens, submicron colloidal matter, viruses, and bacteria from water. The process is called ‘reverse’ osmosis since it requires pressure to force pure water across a membrane, leaving the impurities behind.

The part of precipitation water that runs off the land into streams or other surfacewater.