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Tds |
The abbreviation for
"total dissolved solids". |
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Temporary Hardness |
Water hardness due to the
presence of calcium and magnesium carbonates and bicarbonates, which can
be precipitated by heating the water. Now largely replaced by the term
"carbonate hardness". (See carbonate hardness, permanent
hardness.) |
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Threshold |
A very low concentration of
a substance in water. The term is sometimes used to indicate the
concentration which can just be detected. |
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Throughput Volume |
The amount of solution
passed through an ion exchange bed before the ion exchanger is exhausted. |
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Titration |
An analytical process in
which a standard solution in a calibrated vessel is added to a measured
volume of sample until an endpoint, such as a color change, is reached.
From the volume of the sample and the volume of standard solution used,
the concentration of a specific material may be calculated. |
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Total Acidity |
The total of all forms of
acidity, including mineral acidity, carbon dioxide, and acid salts. Total
acidity is usually determined by titration with a standard base solution
to the phenolphthalein endpoint (pH 8.3). (See acidity.) |
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Total Alkalinity |
The alkalinity of a water
as determined by titration with standard acid solution to the methyl
orange endpoint (pH approximately 4.5); sometimes abbreviated as
"M" alkalinity". Total alkalinity includes many alkalinity
components, such as hydroxides, carbonates, and bicarbonates. (see
alkalinity.) |
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Total Cations |
This is the sum of Ca + Mg
_ Na + K all reported in gpg as CaCO3. These are "positive" ions
and are generally metals. Total cations should always equal total anions. |
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Total Chlorine |
The total concentration of
chlorine in a water, including combined and free chlorine. (See combined
available chlorine, free available chlorine.) |
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Total Coliform |
Bacteria that are used as
indicators of fecal contaminants in drinking water. |
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Total Dissolved Solids (Tds) |
The weight of solids per
unit volume of water which are in true solution, usually determined by the
evaporation of a measured volume of filtered water, and determination of
the residue weight. |
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Total Hardness |
The sum of all hardness
constituents in a water, expressed as their equivalent concentration of
calcium carbonate. Primarily due to calcium and magnesium in solution, but
may include small amounts of metals such as iron, which can act like
calcium and magnesium in certain reactions. (See hardness.) |
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Total Solids |
the weight of all solids,
dissolved and suspended, organic and inorganic, per unit volume of water;
usually determined by the evaporation of a measured volume of water at
105oC in a pre-weighted dish. |
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Toxic |
Having an adverse
physiological effect on humans or other desirable organisms. |
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Toxicity |
The
property of a chemical to harm people who come into contact with it. |
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Trace |
A very small concentration
of a material, high enough to be detected but too low to be measured by
standard analytical methods. |
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Transient, Non-Community
Water System |
A water system which
provides water in a place such as a gas station or campground where people
do not remain for long periods of time. These systems do not have to test
or treat their water for contaminants which pose long-term health risks
because fewer than 25 people drink the water over a long period. They
still must test their water for microbes and several chemicals. |
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Transpiration |
The process in which living
plants release water vapor into the atmosphere, a significant part of the
hydrologic cycle. |
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Treatment Technique |
A specific treatment method
required by EPA to be used to control the level of a contaminant in
drinking water. In specific cases where EPA has determined it is not
technically or economically feasible to establish an MCL, EPA can instead
specify a treatment technique. |
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Tuberculation |
The process in which
blister-like growths of metal oxides develop in pipes as a result of the
corrosion of the pipe metal. Iron oxide tubercles often develop over pits
in iron or steel pipe, and can seriously restrict the flow of water. |
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Turbidity |
A measure of the cloudiness
in water, the result of finely divided particulate matter suspended in
water; usually reported in arbitrary units determined by measurements of
light scattering. (See Nephelometric Turbidity Unit.) |
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Turbidity |
The cloudy appearance of
water caused by the presence of tiny particles. High levels of turbidity
may interfere with proper water treatment and monitoring. |
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Turbulent Flow |
A type of flow
characterized by cross currents and eddies, as opposed to laminar or
streamlined flow. Turbulence may be caused by surface roughness or
protrusions in pipes, bends and fittings, changes in channel size, or
excessive flow rates; turbulence significantly increases pressure drops. |
