Glossary

Learn about the different types of contaminants that might put your family at risk.

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”.
threshold
A very low concentration of a substance in water.  The term is sometimes used to indicate the concentration which can just be detected.
throughput volume
The amount of solution passed through an ion exchange bed before the ion exchanger is exhausted.
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 specific material may be calculated.
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).
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.
total chlorine
The total concentration of chlorine in a water, including combined and free chlorine.
total dissolved solids
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.
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.
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 150 ° C. in a pre-weighed dish.
toxic
Having an adverse physiological effect on man.
trace
A very small concentration of a material, high enough to be detected but too low to be measured by standard analytical methods.
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.
turbidity
A measure of the amount of finely divided suspended matter in water which causes the scattering and adsorption of light rays.  Turbidity is usually reported in arbitrary units determined by measurements of light scattering.  Usually expressed as JTU.
turbulence
A type of flow characterized by cross currents and eddys as opposed to laminar flow.  Turbulence may be caused by curves, bends, and changes in channel size, obstructions, or excessive flow rates and will significantly increase pressure drop.
turbulent velocity
The velocity of water flowing in a conduit above which the flow will always be turbulent and below which the flow may be either turbulent or laminar depending upon circumstances.