With thanks to Water UK, Yorkshire Water and Lenntech BV.

Or click here to view all terms ordered from A-Z.


E. coli (Escherichia coli)

A bacterium taken as an indicator of faecal contamination.


Environment Agency.


The study of interrelation between living organisms and their environment.

Economic Level of Leakage (ELL)

The point where the environmental, economic and social cost of water saved by reducing leakage is equal to the cost of new resources used in managing leakage. The sustainable economic level of leakage (SELL) is based on the same concept, but takes more explicit account of social and environmental costs and benefits.


Water that flows from a sewage treatment plant after it has been treated.

Environmental Quality Objective (EQO)

The description of water quality required to maintain an identified use of a body of water.

Environmental Quality Standard (EQS)

The concentration of a parameter which must not be exceeded if the EQO is to be maintained or achieved.

Estuary (EC)

The transitional area between freshwater and the proper marine area. The outer part of an estuary is limited by the straight line between the furthest seawater extent of the low water line on each side of the estuary.

Estuary (UK)

The transitional area at the mouth of a river between fresh water and coastal waters.


Referring to water that is rich in nutrients such as nitrogen and phosphorous.


Enrichment of water, which causes excessive growth of aquatic plants and increasing activity of anaerobic microrganisms. As a result the oxygen levels in the water quickly decline and the water chokes, making life impossible for aerobic water organisms.

Back to top