Glossary
A glossary of water terms is for the consumer’s use when reading reports on water quality.
There are 81 Glossary definitions
Acidic Solution A Solution that contains significant numbers of (H+) ions.
Action Levels That level of a contaminant in drinking water at which EPA requires the water system to take specified actions such as public education and for treatment process evaluations and modifications.
Algae The simplest of all plant forms, having neither root, stem, nor leaves. Most are microscopic consisting of single cells or colonies of cells. They are present in all natural surface waters. Certain types of algae (particularly the Blue-Green Algae) produce objectionable tastes or odors in drinking water supplies.
Alkalinity The capacity of water to neutralize acids. A property primarily imparted by the water’s content of carbonates, bicarbonates and hydroxides. Alkalinity is expressed in milligrams per liter of equivalent calcium carbonate.
Aquifer A bed of porous rock or sand that carries or holds water and from which water can be extracted.
Available Chlorine A term used for rating hypochlorites as to their total oxidizing power. Dry calcium hypochlorite typically contains 65% available chlorine. Liquid household bleach (sodium hypochlorite) typically contains 5.22% available chlorine.
Bacteria Simple, one-celled microscopic organisms. Although some bacteria cause diseases (pathogenic bacteria), others are harmless and fill indispensable ecological roles such as decomposers.
Base Any compound that dissociates in water to yield hydroxylions (OH-).
Boosters Pumps and pumping facilities located throughout the distribution system to insure proper water pressure for delivery to all points.
Chloride The (CI-) radical or ion. Sodium chloride (NaCL) is common table salt. Chloride ion (Cl-) is found in all natural waters.
Chlorination The application of chlorine to water generally for the purpose of disinfection, but frequently for accomplishing chemicals such as iron, manganese or taste and odor removal.
Chlorine An element (Cl) ordinarily existing as a greenish-yellow gas (Cl2) about 2.5 times as heavy as air. It is commonly used as a disinfectant in water treatment.
Chlorine Residual When added to the water, chlorine not only kills the harmful bacteria but reacts with other substances in the water. Therefore, adequate chlorine must be added so it can react and still have a small measurable amount of chlorine left in the water. This small amount of measurable chlorine is called chlorine residual.
Clarifier Unit that separates particles of dirt from the water and deposits it in a sludge pile.
Concentration A measure of the amount of dissolved substances contained per unit volume of solution. Concentration may be expressed as grains per gallon, pounds per million gallons, or milligrams per liter.
Contamination Any introduction into water of microorganisms, chemicals, wastes or wastewater in a concentration that makes the water unfit for its intended use.
Corrosion Depending upon the characteristics of the water, it will react with metals and chemicals. This reaction can cause corrosion of the pipes, which contain the water. The most common deterioration is seen as rust.
Corrosion Control Methods used to prevent the dissolution of pipe materials into water. Adjustment of pH or the addition of corrosion-inhibiting chemicals like zinc phosphate is commonly used.
Disinfection The removal or inactivation of infectious microorganisms in the water treatment process.
Dissolved Oxygen (DO) The oxygen dissolved in water. It is necessary for respiration by aquatic life and for the oxidation, or breakdown, of organic matter.
Distillation The removal of dissolved substances from water by first evaporating it to steam and then condensing the steam back to water. Distilled water is usually very pure.
Distribution System Pipelines, pumps and tank facilities located away from the plant, which delivers water to customers.
Drinking Water Standards Allowable levels of contaminants (primary and secondary) established by EPA to protect public health and welfare. These are also called Maximum Contaminant Levels (MCLs).
Effluent The treated or untreated liquid that flows out of a pipe. This term is generally used in the water and wastewater industries to describe finished waters discharged into distribution systems or treated waste waters discharged back to natural waters (rivers and streams).
EPA Stands for the United States Environmental Protection Agency (USEPA or EPA). The Federal Agency created in 1970 that implements major environmental legislation. EPA s Office of Drinking Water is given the responsibility of establishing federal drinking water regulations and standards (levels of contaminants, which could be present in water without being harmful to man, when the water is consumed).
Filter Media Layers of porous materials through which water is filtered. This material can include sand, hard coal or anthracite, and gravel.
Filtration The process of removing suspended matter from water as it passes through beds of porous material such as sand or activated carbon.
Fluoride When present in drinking water in the proper amounts, fluoride helps harden the enamel on children’s teeth during the time the teeth are growing (from the time the children lose their baby teeth until they are about 12-14 years of age) and thus prevents dental caries (cavities or decay). If children drink water that has too much fluoride during the time their teeth are growing, brown spots can appear under the enamel of the teeth. This is called mottling of the enamel and the brown spots will remain as part of the permanent teeth. In some states, drinking water treatment facilities are required to add fluoride to the water to provide the optimum level of dental health. (LEHMUA does NOT add fluoride to our water.)
Gastroenteritis Inflammation of the lining membrane of the stomach and the intestines.
Grains Per Gallon (gpg) A measure of the concentration of solutions. It is frequently used when referring to water hardness. 1 gpg = 17.12 mg/L
Gram A metric unit of mass defined as one thousandth of a kilogram; one gram is practically equal to the weight of a cubic centimeter of water (1/454 of a pound)
Granular Activated Carbon (GAC) A treatment technique that relies on the absorbent properties of carbon to remove its contaminants from drinking water. The primary use is organic removal.
Ground Water Water stored underground in the porous rocks and soils, rather than in lakes, streams or otherwise on the surface of the ground. It is a large portion of the total supply of fresh water.
Hardness A characteristic of water caused primarily by the presence of calcium and magnesium salts. High hardness makes it difficult to obtain soap suds without using a larger amount of soap. Other indications of hardness or hard water are where a scale is built up in boilers, in the pipes close to the boiler, or in pipes near hot water heaters. Waters with hardness greater than 200 ppm (12 grains per gallon) are usually considered “hard.” Consumer acceptance to hardness varies widely. Original term came from the fact that beans cooked in hard water remained hard.
Hypochlorites Compounds containing the hypochlorite ion (OCl-). Sodium hypochlorite and caladium hypochlorite are often used as drinking water disinfectants.
Langelier Index A method for reporting the tendency of water to either scale or corrode pipes, based on the pH and alkalinity of the water. Full name is “Langelier’s calcium carbonate saturation index.” A positive value indicates a tendency for the water to deposit a protective mineral scale on the inside pipe surface.
MCL (Maximum Contaminant Level) The highest permissible concentration of a substance allowed in drinking water, as established by the USEPA. These are enforceable standards (laws) designed to be protective of human health and to take into account available monitoring and treatment technologies.
Metric Equivalents 1 U.S. gallon = 3.785 liters 1 liter = 0.264 U.S. gallons (A liter is slightly more than a U.S. quart) 1 cubic foot = 28.317 liters.
MGD Million gallons per day (not thousands as M might indicate).
Microorganism Organisms so small that a single unit cannot be seen by the unaided eye. Microorganisms include bacteria, viruses, protozoa, unicellular fungi and algae.
Micrograms Per Liter (ug/L) One part per billion (ppb).
Million Per Liter (mg/L) One part per million (ppm). The term milligrams per liter is used to express, by weight, the amount of chemical dissolved into one liter of water. One part per million is the equivalent to one milligram per liter.
National Primary Drinking Water Regulations (NPDWRs) The standards and monitoring and notification regulations, which EPA must establish, authorized under the Safe Drinking Water Act Amendments of 1986.
PCBs (Polychlorinated Biphenyls) A group of synthetic organic chemicals used for numerous purposes. Manufacture of PCBs was discontinued in 1976. PCBs are still present in many electrical capacitors and transformers and have been detected in some drinking water sources.
pH Water has the ability to dissolve both alkaline and acid substances. When these substances are dissolved equally, it is said that the water is neutral and has a pH of 7. When the pH of the water is above 7, It means that more alkaline substances have been dissolved. When the pH of the water is below 7, it means that more add substances have been dissolved. The pH scale runs from 0 (most acid) to 14 (most basic).
Picocuries per Liter (pCi/L) This unit is usually use to measure for the amount of radioactivity in water. One pCi is equivalent to 2.22 disintegrants per minute (dpm).
Pollution A condition representing the presence of harmful or objectionable materials in the water.
Potable Water Water which does not contain objectionable or harmful substances and is considered satisfactory for domestic consumption.
ppb One part per billion; equal to one gram of solute per billion grams of solution; ppb and ug/L (microgram per liter) represent the same concentration.
ppm One part per million; equal to one gram of solute per million grams of solution; ppm and mg/L (milligram per liter) represent the same concentration.
Primary Drinking Water Standards Standards (MCLs) established for the protection of public health. Priority Pollutants. A list of 129 industrial pollutants regulated by the Clean Water Act.
Radon A natural radioactive gas. Surface water does not normally contain radon, but some ground waters can contain high levels.
Safe Drinking Water Act The Safe Drinking Water Act of 1974 and its 1986 Amendments are the laws enacted by Congress authorizing the EPA to establish national drinking water regulations.
Salinity Concentration of salts dissolved in water; salt level.
Saturation Index (S.I.) See Langelier Index.
Sodium Is an essential element in the human diet; however, evidence from epidemiologic, clinical, and animal studies suggest that chronic excessive sodium intake is associated with hypertension, defined as an increase in blood pressure. The American Heart Association (AHA) has advocated a sodium-restricted diet for the long-term management of hypertension and has suggested a maximum level of sodium in drinking water of 20 milligram per liter (mglL). However, sodium in drinking water is usually a very small percentage of the normal dietary intake. For example, one large dill pickle may contain more than 2,000 mg sodium, and the average person consumes 5,000 mg per day. Persons on low sodium diets should check with their physician to determine what levels of sodium in drinking water are acceptable for their needs.
Sodium Is an essential element in the human diet; however, evidence from epidemiologic, clinical, and animal studies suggest that chronic excessive sodium intake is associated with hypertension, defined as an increase in blood pressure. The American Heart Association (AHA) has advocated a sodium-restricted diet for the long-term management of hypertension and has suggested a maximum level of sodium in drinking water of 20 milligram per liter (mglL). However, sodium in drinking water is usually a very small percentage of the normal dietary intake. For example, one large dill pickle may contain more than 2,000 mg sodium, and the average person consumes 5,000 mg per day. Persons on low sodium diets should check with their physician to determine what levels of sodium in drinking water are acceptable for their needs.
Soft Water Water which has very little calcium and magnesium dissolved into it, allows soap to form suds easily, does not build up scale in boilers or hot water heaters, is considered soft water. When tested, water with a hardness of 0 to 3 grains per gallon or 0 to 50 milligrams per liter is considered “soft water.” One gram per gallon equals approximately 17 milligrams per liter of water hardness.Soft Water Water which has very little calcium and magnesium dissolved into it, allows soap to form suds easily, does not build up scale in boilers or hot water heaters, is considered soft water. When tested, water with a hardness of 0 to 3 grains per gallon or 0 to 50 milligrams per liter is considered “soft water.” One gram per gallon equals approximately 17 milligrams per liter of water hardness.Soft Water Water which has very little calcium and magnesium dissolved into it, allows soap to form suds easily, does not build up scale in boilers or hot water heaters, is considered soft water. When tested, water with a hardness of 0 to 3 grains per gallon or 0 to 50 milligrams per liter is considered “soft water.” One gram per gallon equals approximately 17 milligrams per liter of water hardness.Soft Water Water which has very little calcium and magnesium dissolved into it, allows soap to form suds easily, does not build up scale in boilers or hot water heaters, is considered soft water. When tested, water with a hardness of 0 to 3 grains per gallon or 0 to 50 milligrams per liter is considered “soft water.” One gram per gallon equals approximately 17 milligrams per liter of water hardness.Soft Water Water which has very little calcium and magnesium dissolved into it, allows soap to form suds easily, does not build up scale in boilers or hot water heaters, is considered soft water. When tested, water with a hardness of 0 to 3 grains per gallon or 0 to 50 milligrams per liter is considered “soft water.” One gram per gallon equals approximately 17 milligrams per liter of water hardness.
Solute The substance is dissolved in a solution.
Solution A liquid containing a dissolved substance. The liquid alone is called the solvent, the dissolved substance is called the solute. Together they are called a solution. In an aqueous solution of sodium chloride (table salt) the solvent is water and the solute is table salt.
Suspended Solids (SS) Small particles of matter, such as fine soils or clays, suspended in the water. SS is a measure of the materials that can be filtered out of a water sample.
Taste/Odor It is difficult to separate taste from odor. Due to the fact that we rely simultaneously on a combination taste and odor sensory organs to come up with our individual perceptions of flavor, feels and smells of substances ingested and/or inhaled. Because water can dissolve chemicals and minerals, it takes on the taste of the chemicals or minerals. Depending on what the water comes in contact with, each different source of supply has its own distinctive taste/odor. When someone first drinks the water, they may find it unpleasant because the taste is different from what they are accustomed to. As one continues to drink the water over a period of time, they become accustomed to the taste and no longer find it unpleasant.
THMs (Trihalomethanes) A group of volatile organic compounds formed when chlorine reacts with naturally occurring humic (organic) substances in water. (See Trihalomethanes.)
Total Dissolved Solids (TDS) The total of the dissolved salts, minerals and other matter (by weight) In a measured quantity of water; usually stated in parts per million (ppm) or milligrams per liter (mg/L). Dissolved solids generally are not removed from water by filtration.
Total Organic Halogen (FOX) Is a measure of the organic compounds associated with chlorine, bromine and iodine (halogens), including trihalomethanes. Since most halogenated organics are suspected of being toxic or carcinogenic, the TOX in water is a useful indicator of toxic contaminants.
Toxic Of, relating to, or caused by a poison.
Toxicity The quality or degree of being poisonous or harmful to plant, animal or human life.
Toxicology The study of the harmful effects of substances on living systems.
Treated Water Water that had been treated chemically and/or physically to make it suitable for its intended use.
Turbidity A measure of water clarity. Turbidity indicates the presence of suspended solids. High turbidity water is not only visually unacceptable to the consumer; it can shield microorganisms from the action of disinfectants.
VOCs (Volatile Organic Compounds) Lightweight organic compounds that vaporize or evaporate easily. Many industrial solvents like TCE and TCA belong to this class of compound.
Water Equivalents Table 1 gallon = 0.13 cubic feet= 8.34 lbs. of water 1 cubic foot = 7.48 gallons = 62.4 lbs. of water 1 acre-foot = 43,560 cubic = 325,861 gallons (an acre-foot covers 1 acre of land 1 foot deep) 1 cubic foot per second (cfs) = 449 gallons per minute 1 cubic foot per second = 646,317 gallons per day For 24 hours = 1.983 acre-feet For 30 days = 59.5 acre-feet For 1 year = 72 acre-feet 1 million gallons = 1,336.9 hundred cubic feet = 3.07 acre-feet 1 million gallons per day (gpd) = 1,120 acre-feet per year 1 million gpd = 1.55 cubic feet per second An acre-foot supplies a family of 5 for 1 year
Water Quality The chemical, physical and biological properties of water which affect its suitability for use.
Water Quality Units
Water Quality Units 1 part per million (ppm) = 1 milligram per liter (mg/L) 1 part per billion (ppb) = 1 microgram per liter (ug/L) 1 part per trillion (ppt) = 1 nanogram per liter (ng/L) 1 ppm = 1,000 ppb = 1,000,000 ppt 1 gram = 1,000 mg = 1,000,000 ug = 1,000,000,000 ng NOTE: These units represent extremely small amounts. To put things in perspective, consider that: 1 ppm is like 1 minute in 2 years. 1 ppb is like 1 inch in 16,000 miles. 1 ppt is like 1 penny in $10 billion.
Water Table The geographic level where ground water is encountered in a well in an unconfined aquifer.
Watershed The land area from which water drains to a given point, such as a reservoir, stream, river, or storm water catchment area.