Terminology Services

Drinking Water Technical & Legal Terms

Long Name:

Drinking Water Glossary: A Dictionary of Technical and Legal Terms Related to Drinking Water

Description:

A dictionary of technical and legal terms related to drinking water.

Publishing Organization:

Office of Water/Office of Ground Water and Drinking Water

Last Update:

February 17, 2009

Program Site:

Search Terms (Contains): alkalinity

	Term
	Alkalinity	Definition: (AL-ka-LIN-it-tee) The capacity of water to neutralize acids. This capacity is caused by the water's content of carbonate, bicarbonate, hydroxide and occasionally borate, silicate, and phosphate. Alkalinity is expressed in milligrams per liter of equivalent calcium carbonate. Alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have a high alkalinity. Alkalinity is a measure of how much acid can be added to a liquid without causing a great change in pH.
	Methyl Orange Alkalinity	Definition: A measure of the total alkalinity in a water sample. The alkalinity is measured by the amount of standard sulfuric acid required to lower the pH of the water to a pH level of 4.5, as indicated by the change in color of methyl orange from orange to pink. Methyl orange alkalinity is expressed as milligrams per liter equivalent calcium carbonate.
	Phenolphthalein Alkalinity	Definition: (FEE-nol-THAY-leen) The alkalinity in a water sample measured by the amount of standard acid required to lower the pH to a level of 8.3, as indicated by the change in color of phenolphthalein from pink to clear. Phenolphthalein alkalinity is expressed as milligrams per liter equivalent calcium carbonate.

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