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Water Dictionary - Letters T-Z


2,3,7,8-TCDD – EPA priority pollutant

TEAM Studies - Acronym for Total Exposure Assessment Methodology Studies. The goal of these long-term series of EPA-conducted studies is to determine the actual exposure of people to a substance or substances

Tebuconazole – CCL-3, EPA contaminant candidate; origin: fungicide

Tebufenozide – CCL-3, EPA contaminant candidate,origin: insecticide

Tellurium (Te) – element; CCL-3 EPA contaminant candidate

Terbacil – CCL1- EPA contaminant candidate

Terbufos (Terbufos sulfone) – CCL1 and CCL-3 – EPA contaminant candidates; origin: insecticide & breakdown product

1,1,2,2-tetrachloroethane - EPA priority pollutant; CCL-1 EPA contaminant candidate

Tetrachloroethylene - EPA priority pollutant; origin: discharge from factories and dry cleaners; toxicity potential: cancer; MCL = 0-0.005

Thallium (Tl) – element; EPA priority pollutant; origin: leaching from ore-processing, factory discharge; toxic potential: hair loss; MCL = 0.0005 – 0.002

Thidicarb – CCL-3 EPA contaminant candidate; origin: insecticide

Thiophanate-methyl – CCL-3 EPA contaminant candidate

Threshold - The lowest dose of a chemical at which a specific measurable effect is observed. Below this dose, the effect is not observed.

Toluene - EPA priority pollutant; origin: discharge from petroleum factories; toxicity potential: nervous system, kidney or liver problems; MCL = 1

Toluene diisocyanate – CCL-3 EPA contaminant candidate; origin: plastic manufacture

Total Bacteria Count (TBC) - an estimate of the number of viable units of bacteria per milliliter of water under the conditions of testing. Note that no single method, culture medium or conditions of incubation can satisgy the growth requirements of all bacteria in a water sample.

Total Coliforms (including fecal coliform and E. Coli)measurement to determine if fecal bacteria are present in water; MCL = 0

Total dissolved solids - the total weight of dissolved substances in water, including those which are capable of conducting electricity and those which are not. EPA secondary standards = 500 mg/L

Total trihalomethanes (TTHMs) - origin: byproduct of drinking water disinfection; toxicity potential: cancer; MCL = 0.080

Toxaphene - EPA priority pollutant; origin: runoff or leaching from insecticide; toxicity potential:cancer; MCL = 0 – 0.003

Toxic - Harmful, poisonous, dangerous to health; can cause or induce a variety of health risks; at worst can be fatal.

Toxicant - A poison.

Toxicity - The innate ability of a contaminant to cause injury to biological tissue.

Toxicology - The study of the adverse effects of chemicals on living organisms.

2,4,5 -TP (Silvex) –origin: runoff or leaching frominsecticide; toxicity potential: cancer; MCL = 0.5

Triazines (and degradation products) - CCL-1 EPA contaminant candidates

Tribufos – CCL-3 EPA contaminant candidate; origin: insecticide

1,2,4-Trichlorobenzene – EPA priority pollutant; origin: discharge from textile factories; toxicity potential: adrenal glands; MCL = 0.7

Trichloroethane (1,1,1-or 1,1,2-) - EPA priority pollutant; origin: factory discharge; toxicity potential: liver or circulatory issues; MCL = 0.20 for 1,1,1-tce; MCL = 0.003-0.005 for 1,1,2-tce

Trichloroethylene - EPA priority pollutant; origin: factories; toxicity potential: cancer; MCL = 0-0.005

2,4,6-trichlorophenol - CCL-1, EPA contaminant candidate

1,2,3-Trichloropropane – CCL-3 EPA contaminant candidate; origin: paint manufacture

triethylamine – CCL3- EPA contaminant candidate; origin: many industries

1,2,4-trimethylbenzene – CCL-1, EPA contaminant candidate

Triphenyltin hydroxide (TPTH) – CCL3-, EPA contaminant candidate; origin: pesticide

TSCA - Toxic Substances Control Act.

Turbidity - a cloudy appearance in water that is caused by a suspension of colloidal or particulate matter.

TVOCs - Total volatile organic compounds: these are compounds that evaporate readily and have low solubilities in water; generally man-made in origin, their presence in water is a sign of local contamination issue – such as factory run-off. Two VOCs that may be found in unpurified drinking water are Benzene and MTBE.


Ultrafiltration – similar to micro-filtration, ultra filtration systems remove impurities from water by passing it through a "screen". The screen in this case is a semi-permeable membrane that effectively separates molecules in water, allowing certain molecules to pass through it while retaining others. Removes: Sediments and extremely fine particles, microorganisms. Advantages: Highest quality water for lowest energy investment; Disadvantages: May clog. Can be expensive if large amounts of sediment exist. Does not remove dissolved particles. <>

Ultraviolet Radiation (Water Purification Method) - Low level ultraviolet light kills bacterial and viral pathogens. The amount of radiation produced is negligible, and it leaves no trace. A typical UV sterilizer looks like a stainless cylinder with water inlet on one end, and a water outlet on the other. Water passes through a chamber that has a quartz lamp which performs disinfection. Removes:
Bacteria, Viruses; Advantages: Sanitizes water; Disadvantages: Does not remove suspended particles, ions, organic chemicals, heavy metals, or ions. <Water Purification Technologies: Water Guide>

Under Sink and UnderCounter Water Filters – Point of use systems for filtering tap water in the kitchen; generally have a separate faucet. <>

Uranium (U) – element; origin: erosion of natural deposits; toxicity potential: cancer; MCL = 0

Urethane – CCL3- EPA contaminant candidate; origin: paint ingredient


Vanadium (V) – element; CCL-1 EPA contaminant candidate; origin: industrial ingredient

Vinclozolin – CCL-3, EPA contaminant candidate; orgin: fungicide

Vinyl chlorideEPA priority pollutant; MCL = 0 – 0.002; origin: factory discharge, pvc leachate; toxicity potential: cancer

Viruses – enteric; the smallest of all 'life forms' containing either RNA or DNA; toxicity potential: gastrointestinal distress (vomiting, diarrhea, cramps); MCL = 0

VOCs - See Volatile Organic Compounds.

Volatile Organic Compounds (VOCs) – compounds that evaporate readily so are 'volatile', and have low solubility in water <>. Origin: chemical industry (and some natural origins); toxicity potential: some VOC's may cause cancers. Often best removed via activated carbon filtration <> or reverse osmosis <>


Water coolers (POU) – point of use water coolers, P\plumbed directly into your cold water line and use advanced water filtration systems. <>

Water filters – A variety of filtration devices used for water purification, like here.

Water filter cartridges – replacement filter system inserts for water purification are called cartridges; see Sediment Filters and/or Carbon Filters <>

Water filtration – method for purification of drinking water; varies in terms of type of contaminant requiring removal.

Water ionizers - Water ionizers use a process that is different from standard mechanical or chemical water filtration. Along with regular water filters, ionizers rely on a process of electrolysis, or ionization. This allows water ionizers to produce water of higher (and some machines - of lower) pH levels, even much higher than normal "neutral" pH levels of 7 to 7.5 (not to be confused with skin pH, which is 5). Increasing scientific evidence suggests health benefits from drinking higher pH, or alkalinized water <>

Water pollution – has many sources, both natural and man-made. As shown in the figure at <> they range from atmospheric deposition to fertilizers and pesticides to industrial deposition, and runoff from rural and urban sources <>.

Water purification technologies - There are many methods used to remove impurities and contaminants from water. Each of the water purification technologies is best at removing one type of contaminant from water, and may not be effective at all for others. <Water Purification Technologies>

Water purification – technologies for removal of contaminants <>

Water softeners - <>

Water test kits – in-home water test kits as well as Science Fair, and laboratory water test kits. Check your drinking water with complete test kits, drinking water test kits, bacteria check tests and more. <>

WHO - Acronym for the World Health Organization.

Whole house filters – variety of systems for homes, apartments, and small businesses. Three categories include Budget water filters, Large residential home water filters, and Specialty and Well systems. Whole House Filter Systems>

WQA - Acronym for the Water Quality Association.

Water Softening - process of removing hardness ions from water , usually via a water softener. Water softeners typically use ion exchange media.


Xylenes (total = meta- ortho-, para-) -origin: factory discharge; toxicity potential: nervous system damage; MCL= 10


none listed


Zinc (Zn) – element; EPA secondary standards = 5 mg/L

Ziram – CCL-3, EPA contaminant candidate; origin: fungicide


[1] The majority of compounds listed are from the EPA list of drinking water contaminants <> [accessed 29 January 2015]

[2] Data for MCL values from <> (Accessed Dec 2014)

[3] Toxicity potentials for all compounds having MCL values from <> (Accessed Dec 2014)

[4] EPA contaminant candidates from lists below accessed December 2014 & January 2015

CCL-1 <>

CCL-2 <>

CCL-3 <>

CCL-4 <>

[5] EPA priority pollutants <>

Definitions: "The Priority Pollutants are a set of chemical pollutants EPA regulates, and for which EPA has published analytical test methods... The pollutant had to have been reported as found in water with a frequency of occurrence of at least 2.5%." [accessed12/31/2014]