Analytical Balance Corporation Glossary

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A substance that releases hydrogen ions (H+) in solution and decreases pH (see pH). Lemon juice and vinegar are examples of weak to moderate acids. Stomach acid is a strong acid. Battery acid is very strong.

A measure of a solution’s ability to resist changes in pH when base is added.

The measure of a solution’s ability to resist changes in pH when acid is added. This is a traditional drinking water quality parameter and is a measure of the buffering capacity of the water. Samples with a low alkalinity tend to be more corrosive and may affect metal pipes and fixtures.

A metal which may cause health problems in higher amounts. No guidance is currently available on a limit.

A reduced form of nitrogen, NH3, found in septic wastes and fertilizers. Properly functioning waste treatment systems are designed to convert ammonia to less toxic forms (nitrification). The presence of ammonia in drinking water may indicate pollution from septic waste.

A negatively charged ion.

Anionic Surfactants
Commonly known as soaps. They can cause foaming in bodies of water if discharged into the environment. Antimony A metal with high toxicity. The MCL is 0.006 mg/L.

A metalloid with high toxicity and can occur naturally in our area. The MCL is 0.010 mg/L. Toxicity and treatment strategies vary with the form of arsenic, so we recommend an arsenic speciation test if you have arsenic in your drinking water.

A naturally occurring fibrous substance that can cause irritation and lung cancer when inhaled. It can be found in drinking water from old asbestos-lined water mains. The MCL is 7 million fibers/liter.

A metal with slight toxicity, but has low solubility in water and is relatively rare. The MCL is 2 mg/L.

An alkaline substance that absorbs acid (H+) in solution, releasing hydroxide (OH-) and increasing pH (see pH). Baking soda (sodium bicarbonate) is a weak base, soap is a moderate base, and drain cleaner (lye) is a strong base.

A metal with high toxicity. The MCL is 0.004 mg/L

Biochemical Oxygen Demand. This is a measure of how much oxygen is required by bacteria to 'digest' waste. Release of wastes with high BOD can cause oxygen depletion and fish kills in water bodies.

A metal with high toxicity. The MCL is 0.005 ug/L.

Essential to human life and non-toxic. (see Hardness)

A positively charged (usually metallic) ion.

Carbonaceous Biochemical Oxygen Demand. It is a variation of the BOD test which excludes the oxygen needed to digest nitrogen wastes. (see also BOD) CFU/100 mL Colony Forming Units per 100 milliliters of sample. This is the unit used for bacterial counts. A colony may derive from a single bacterium or from a small "clump" of bacteria in the original sample, so CFUs don't necessarily tell you the exact number of bacteria in the sample. Note that we use growth media which encourages growth of the bacteria of interest and suppresses growth of other types of bacteria, so the count we report is only the bacteria of interest.

Chain of Custody
A legal document that establishes the who, what, where, when, and why of (a) sample(s) submitted to us. It also documents who was in possession of the sample(s) from the time they were taken to the time of receipt by the laboratory.

A naturally occurring mineral anion, Cl-. It is a component of table salt. Very high chlorides in drinking water can contribute to corrosiveness and may indicate a source under the influence of ocean water, salt deposits, or road salt. Some water softeners also use salt and can contribute to high chloride levels.

An oxidizing agent often used to disinfect water supplies and pools. High levels can have toxic effects. Use of disinfection agents can lead to potentially harmful byproducts such as THM's & HAA's. Free chlorine is a measure of uncombined chlorine; total chlorine includes both free chlorine and chlorine that is combined with nitrogen in compounds called chloramines.

A metal with some toxicity. Some forms, especially Hexavalent Chromium are particularly harmful, while other forms are harmless (a small amount of chromium is essential to life). The MCL for Total Chromium is 0.1 mg/L.

A metal that is only toxic in very high quantities.

See Total Coliform.

A group of bacteria, visible to the naked eye, formed on a plate of growth media. Typically, 100 mL of sample is run through a disc-shaped filter, which is then placed on a petri dish of media. This media causes the bacteria of interest to multiply quickly, forming a visible colony. Note that the media also discourages growth of other types of bacteria, so colonies only form from the bacteria of interest.

See Chain of Custody

Chemical Oxygen Demand. This is a measure of how much oxygen is required to chemically 'digest' waste.

A metal that is toxic to all life in high concentrations, but is essential to life in small quantities. The principal source of copper in drinking water is the corrosion of copper pipes. It is more harmful for people with thyroid disease. The MCL is 1.3 mg/L

A toxic anion, CN-, which can cause death in moderate doses. The MCL is 0.2 mg/L.

Dissolved Oxygen (DO)
The amount of oxygen dissolved in a solution. Natural waters need moderate to high DO to support life. Low DOs can lead to fish kills and other negative effects in bodies of water.

Dissolved Solids
The amount of solids, such as salts, dissolved in a solution. Totally pure water has no dissolved solids. You can estimate the dissolved solids of most waters by multiplying the specific conductance by 2/3rds.

E. coli
Escherichia coli is a species of bacteria. It is considered both a total and fecal coliform. It naturally occurs in the intestines of all warm-blooded animals. While most variants of E. coli are harmless, some are extremely pathogenic and cause infections with very high mortality rates, especially in the young and elderly. Any presence of E. coli in drinking water indicates fecal contamination and is considered an acute health violation that will invoke a boil-water order. The MCL is "Absent" which means it must be totally absent for water to be considered safe for use.

A broad family of bacteria which can survive in a wide range of environments. Enterococci testing is used to check safety of beaches for swimming. Presence of Enterococci is a good indicator of the presence of human pathogens. Large PWSs also test for Enterococci if total coliform is found in their drinking water.

Fecal Coliform
Refers to a broad class of bacteria, including E. coli, which typically occur in the fecal matter of warm-blooded animals. They are adapted to living in the gut of warm-blooded animals and can cause disease.

A mineral anion, F-, which occurs naturally, though usually in very low amounts. It is useful in preventing cavities, so many municipalities add fluoride at a level of 1 mg/L to the drinking water. Higher doses, around 8 mg/L and higher can cause negative effects such as tooth staining and skeletal problems. Very high doses may be fatal. The MCL for fluoride is 4.0 mg/L grains per gallon or gr./gal. or gpg is a traditional unit for hardness measurement. To convert mg/L of hardness (as CaCO3) to gpg, divide by 17.1.

Gross Alpha
A count of alpha radiation in a sample. Alpha radiation is relatively harmless outside of the body, but ingestion or inhalation of alpha emitting substances is particularly harmful and can cause cancer and genetic damage. The MCL is 15 pCi/L, excluding alpha emission from Uranium and Radon.

Gross Beta
A count of beta radiation in a sample. Beta radiation is moderately harmful outside of the body, but ingestion or inhalation of beta emitting substances is harmful and can cause cancer and genetic damage. There are overall limits for Beta and Gamma emission of 4 millirem/yr; however, this generally does not pertain to our clients.

HAAs or HAA5
Haloacetic acids, such as mono-, di-, and tri- chloroacetic acids. They are typically found in water after disinfection with chlorine or bromine. The MCL for total THMs is 60 ug/L.

A traditional measure of water quality that includes divalent cations, mostly calcium and magnesium. Waters with very little hardness tend to be corrosive, while high hardness leads to soap scum, scale formation, and poor washing properties. Some hardness is a "good" thing. We advise that you get your exact hardness level checked before being sold a water softener. We recommend a hardness between 50 and 150 and report it as mg of CaCO3 (calcium carbonate) per liter. To convert mg/L to grains per gallon (gr/Gal) divide by 17.1.

Hexavalent Chromium (aka Hex Chrom or Cr6)
A highly oxidized form of Chromium, a potentially toxic metal. Hexavalent chromium is the most toxic form and is a carcinogen.

HPC or Heterotrophic Plate Count
The number of heterotrophic colonies which grow on a non-selective, simple nutrient medium. These include many coliforms, yeasts, molds, and other types of bacteria. These can be beneficial as well as harmful.

Inorganic Contaminants (IOC)
A list of inorganic substances which is promulgated by the MA DEP and USEPA. These substances must be tested for by PWSs. The list includes: Antimony, Arsenic, Barium, Beryllium, Cadmium, Chromium, Mercury, Nickel, Selenium, Sodium, Thallium, Free Cyanide, and Fluoride.

A metal that may cause health problems at very high levels, but is essential to life in smaller amounts. Most iron in drinking water is in the ferric (rust colored) form and can not be used by humans. It also causes staining, deposits, and unpleasant taste in household water. We give clients an advisory limit of 0.3 mg/L.

Iron Bacteria
A type of bacteria which live in iron-rich water. They oxidize manganese and ferrous iron (a greenish, soluble form of iron) to ferric iron (a rusty and not soluble form). This can cause fouling and clogging in water systems and plumbing (e.g. a well tank), staining of fixtures, and off taste and odor when water is high in iron.



A metal with high toxicity, especially in children and pregnant women. The principal source of lead in drinking water is the corrosion of older pipes, fixtures, and solder. The use of lead in plumbing has been outlawed since 1986. The MCL is 0.015 mg/L

The Massachusetts Department of Environmental Protection. Among many other duties, this agency certifies testing labs and has primacy in the enforcement of drinking water safety and waste water discharge.

Essential to human life and non-toxic. (see Hardness)

A metal that may cause health problems at high levels. It also causes staining, deposits, and unpleasant taste in household water. While there is currently no limit, the MA DEP is considering adopting a “guidance level” for aesthetic and infant health reasons. We advise clients that 0.05 mg/L is a good limit for aesthetic reasons.

Matrix (pl. matrices)
A term for the type of sample. Drinking water, waste water, and soil are examples of matrices.

The Maximum Contaminant Level as established by the Commonwealth of Massachusetts, in conjunction with the USEPA. It is the maximum allowable amount of a substance in drinking water.

A metal with very high toxicity, especially for children and pregnant women. The MCL is 0.002 mg/L. Also, be aware that you can get mercury from the foods you eat, especially certain fish.

Milligrams per liter. About 18 grains of table salt in a gallon milk jug is 1 mg/L. It is equivalent to parts per million or ppm. To convert mg/L to ug/L or ppb, multiply by 1000.

A metal of low toxicity that is essential to humans in small amounts. It is found naturally, in some stainless steels, and "moly" grease.

A metal of significant toxicity, especially in combination with Cadmium. The MCL is 0.1 mg/L.

An oxidized form of nitrogen, an anion, NO3-. It is found in nature as saltpeter. It is a common byproduct of sanitary waste treatment and also found in high amounts in fertilizer. Run-off from waste treatment and fertilizer can lead to high nitrate levels in water bodies, causing algal blooms and fish kills. Nitrate can also be harmful in drinking water and the MCL is 10 mg/L (as nitrogen).

An oxidized form of nitrogen, an anion, NO2-. It is a common byproduct of sanitary waste treatment. Nitrite is also harmful in drinking water, especially for infants, and the MCL is 1 mg/L (as nitrogen).

Nephelometric Turbidity Units and is the standard unit for turbidity.

The odor of a sample. For drinking waters with an odor, we determine an odor number by diluting the sample until the odor is no longer perceived. The last dilution at which the odor was perceived is the odor number. A secondary limit of 3 is used for PWSs for aesthetic reasons.

Picocuries per liter, a unit of radioactivity per liter of water. It accounts for both the concentration of radioactive substances and the amount of radiation those substances emit.

Man-made organic or inorganic compounds of varying properties used in agriculture, horticulture, golf courses, etc. They include some herbicides, insecticides, and fungicides. These vary widely in both toxicity and persistence in the environment.

A measure of the concentration of H+ ions in a solution. H+ is acidic and therefore pH is a measure of how acidic (or alkaline) a solution is- note this is not the same as alkalinity or acidity. pH is a logarithmic scale, so a change of 1 pH unit means 10 times more or less H+ ions. A pH of 7 is neutral, lower pH's are acidic and higher pHs are basic.

An oxidized phosphorus anion, PO4-3. It is found in many natural minerals, some detergents, and fertilizers. Run-off from waste treatment and fertilizer can lead to high phosphate levels in water bodies, causing algal blooms and fish kills.

A set of tests offered by Analytical Balance which includes bacteria (see total coliform/E. coli), pH, specific conductance, turbidity, alkalinity, hardness, ammonia, nitrate, nitrite, chloride, sulfate, sodium, potassium, calcium, magnesium, iron, manganese, lead and copper.

A naturally occurring metallic mineral component. Potassium is essential in a good diet, but high doses can cause problems in sensitive individuals and extreme amounts can cause death.

Parts per billion - see ug/L.

Parts per million - see mg/L.

PP13 (Priority Pollutant 13)
A list of toxic metals. Testing for these is often required for discharge permits. The list is: Antimony, Arsenic, Beryllium, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Selenium, Silver, Thallium, and Zinc

A genus of bacteria, many of which are pathogenic. They have the ability to survive in improperly maintained pools, hot tubs, and spas. Pseudomonas testing is recommended, and often required, for these. PWS A Public Water Supply and falls under varying levels of regulation by Massachusetts DEP based on the population served.


Radiation emitting substances. Radionuclide testing may include Gross Alpha, Gross Beta, Radium, Radon, and Uranium. See individual terms for more info.

A radioactive element formed naturally from the decay of other radioactive elements and formerly used in "glow-in-the-dark" watch faces, etc. Ingestion is dangerous, as it concentrates in the bones and can cause bone and marrow (blood) cancers. Two isotopes (forms) of Radium, 226 and 228, are tested and the MCL for the combined amount is 5 pCi/L.

A highly radioactive but otherwise inert gas. It occurs naturally from the decay of uranium and other radioactive elements. It is colorless, odorless, and tasteless. Inhaling or ingesting radon is very dangerous and is a leading cause of lung cancer in non-smokers. The Massachusetts MCL is 10,000 pCi/L. Radon is actually much more dangerous in your indoor air. It can percolate through the ground and accumulate in your house. If you have significant levels of radon in your water, you are urged to test your indoor air.

RCRA8 (pronounced "wreck-rah 8")
A list of toxic metals. Test for these is often required for discharge permits. The list is: Arsenic, Barium, Cadmium, Chromium, Lead, Mercury, Selenium, and Silver.

Reverse Osmosis or RO
A technique of water purification which uses membranes and high pressure to filter ions and other impurities out of water.

Standard Units and is used for parameters like pH which do not have dimensional units.

Secondary Contaminants (SEC-CON)
A list of parameters which is promulgated by the MA DEP and USEPA. These must be tested for by PWS's. The list includes: pH, Odor, Color, Turbidity, Alkalinity, Hardness, Dissolved Solids, Potassium, Calcium, Magnesium, Iron, Manganese, Aluminum, Copper, Silver, Zinc, Chloride, and Sulfate.

A naturally occurring non-metallic trace element. It is essential in small amounts, but may be toxic in higher doses. The MCL is 0.050 mg/L.

Semivolatiles or SVOC
Semivolatile Organic Compounds. There are many compounds tested in a SVOC battery and vary widely in toxicity.

Silica or silicon dioxide
The second most abundant substance on Earth and is the principal component of quartz, sand, and glass. Recent studies have shown that ingestion of moderate amounts of dissolved silica is important to protect against dementia. It is used as a corrosion control agent in some water supplies. Very high concentrations of silica in drinking water can cause some scaling and water purification problems.

A metal which may cause health problems in higher amounts. No guidance is currently available on a limit.

A natural metallic mineral component found in salt. Too much sodium will cause high blood pressure and we advise clients to limit sodium in water to 20 mg/L which is the guidance level accepted by the MA DEP. Those with high blood pressure, heart problems, and on low-sodium diets should be particularly aware of the sodium levels in their drinking water. Some common water softening systems use salt to displace calcium and magnesium, causing high sodium levels. High sodium levels may also indicate salt water intrusion and can contribute to corrosion of metal pipes and fixtures.

Specific Conductance or Conductivity
A measure of how well a sample conducts electricity and is a traditional measure of water quality. Higher conductivity indicates that there are more ions or salts in the solution. Absolutely pure water is a very poor conductor. High conductivity water may be contaminated by salt water or salt deposits and is typically corrosive to metal pipes and fixtures. Ironically, very low conductivity water can also be corrosive.

A metal which is chemically similar to calcium and considered non-toxic.

An oxidized form of sulfur, an anion, SO4--, which is naturally occurring. Exceedingly high sulfates in drinking water may cause gastrointestinal problems. An advisory limit of 500 mg/L has been adopted by the Commonwealth.

A reduced form of sulfur, an anion, S--, which is a natural byproduct of decay. It is responsible for "rotten egg" odors in marshes and water. Breathing or ingesting very extreme amounts of sulfide is toxic; however naturally occurring amounts are not harmful. It is very unpleasant, though, even at low concentrations and should be removed from drinking water for aesthetic reasons.

Synthetic Organic Compounds or SOCs
Man-made organic compounds of varying properties. Some are used in industrial processes and agriculture. SOCs include some pesticides and plasticizers.

Threshold Odor Number, the standard unit for odor.

Tannin & Lignin aka Tannic Acids
Are natural products of vegetation and its decay. They can impart off color, taste and odor to drinking water.

A highly toxic metal. The MCL is 0.002 mg/L

THMs are Trihalomethanes
A grouping of compounds including chloroform, bromodichloromethane, dibromochloromethane, and bromoform and are typically found in water after disinfection with chlorine or bromine. The MCL for total THMs is 80 ug/L.

A metal which can be toxic.

A corrosion resistant metal which is considered non-toxic.

Title V (Title 5)
A set of state laws governing the treatment of septic waste. Among other things, these laws require testing of any drinking water source within 100 feet of a septic system. When a property is being sold, the septic system must be in good order and any drinking water sources in the 100 foot zone must be tested- this testing is what we commonly call a Title 5 test. The state mandates testing for bacteria (total coliform), nitrate, and ammonia. However, your local authorities (board of health) may require additional parameters, and they have the final say as to testing requirements.

TKN or Total Kjeldahl Nitrogen
A measure of both ammonia and organic nitrogen in a sample. It is a traditional waste water parameter and, along with nitrate and nitrite, contributes to total nitrogen. Most wastewater permits, especially in sensitive areas like Cape Cod, require a total nitrogen of less than 10 mg/L for discharge into the environment.

Total Coliform
A broad category of bacteria which forms colonies. They can be found naturally in water and soil environments. E. coli is one example of a coliform. Since these are used as “indicator” organisms, the presence of coliform may indicate contamination and requires action (further testing). The MCL is "Absent" which means that coliform must be absent for drinking water to be considered safe.

Total Nitrogen
A measure of all oxidized or reduced forms of nitrogen- see TKN. The parameters used to calculate total nitrogen are nitrite, nitrate and TKN.

The "cloudiness" of a sample. It is a traditional water quality measure. While high turbidity is not itself harmful, it may contribute to clogging of plumbing and the cause of the high turbidity should be investigated. Some causes of turbidity can be harmful or unpleasant.

ug/L or µg/L
Micrograms per liter, a very tiny concentration. One grain of table salt in a gallon milk jug is about 57 ug/L. Micrograms per liter is also equivalent to ppb or parts per billion. To convert ug/L to mg/L or ppm, divide by 1000.

umho/cm or µmho/cm or uS/cm or µS/cm
Micromhos per centimeter or microSiemens per centimeter and is the standard unit of specific conductance and conductivity for water samples. Note that a mho and a Siemen are equivalent. Uranium A radioactive element and alpha emitting substance that occurs naturally in our area. Although harmful, naturally occurring Uranium is quite stable and the body is able to excrete it relatively rapidly, thus minimizing the probability of harm from its radioactivity. The MCL is 0.030 mg/L.

A metal found in some stainless steel. Vanadium compounds are considered to be toxic, but are poorly absorbed when ingested. There is currently no MCL.

Volatiles or VOC
Volatile Organic Compounds. There are over 80 VOC's which we can test for and they range from virtually non-toxic to very toxic. A typical VOC test for drinking water is a "524" and includes approximately 60 compounds. MCL's on individual compounds are as low as 5 ug/L. See our "Services" and "Volatiles" pages for more info.

Water Softener
A device or system which lowers the hardness of water. Some systems are also used for iron removal, though there are more specific devices for that purpose. Water softeners are generally "oversold" to consumers as they provide a high profit margin for water filter companies. We strongly advise clients to check hardness levels before being sold a softener, as there are disadvantages to softened water. See Hardness and Sodium for more info.



A metal essential to life in small amounts, but toxic in high amounts. Free zinc ions can be particularly toxic to aquatic life.