Glossary | Letter T

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Total coliform

There are many variations of bacteria.  The group of bacteria known as coliform is dangerous to human health and should not be ingested under any circumstances. As an indicator of degradation of the microbiological quality of water, “total coliform” is a measure, usually expressed as parts per million of all forms and variations of that particular bacterial description.

Toxic Substance

A contaminate or contaminates which, after release into the environment, may, on the basis of existing information, cause death, cancer or genetic mutations and/or other forms of physiological, anatomical or behavioral abnormalities in organisms or their offspring. Exposure may be by ingestion, inhalation or assimilation into an organism, either directly from the environment (water, air), or indirectly through the food chain.

THMs (Trihalomethanes)

Volatile organic compounds produced during chlorination of water. The long term health effects of THMs are unknown, but are the subject of current debate.


Refers to water that is cloudy in character. Usually expressed in NTUs, or nephelometric turbidity units.