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Drinking Water Quality Glossary Cheat Sheet (DRAFT) by [deleted]

This is a draft cheat sheet. It is a work in progress and is not finished yet.


Action Level (AL): The concen­tration of a contam­inant which, if exceeded, triggers treatment or other requir­ements which a water system must follow.
CU: Color unit.
Maximum Contam­inant Level (MCL): The highest level of a contam­inant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment techno­logy.
Maximum Contam­inant Level Goal (MCLG): The level of a contam­inant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.
Maximum Residual Disinf­ectant Level (MRDL): The highest level of a disinf­ectant allowed in drinking water. There is convincing
evidence that addition of disinf­ectant is necessary for control of microbial contam­inants.
Maximum Residual Disinf­ectant Level Goal (MRDLG) The level of a drinking water disinf­ectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinf­ectant to control microbial contam­ina­tion.
NA: Not applic­able.
ND: Not detected.
NJ RUL: New Jersey Recomm­ended Upper Limit.
NTU: Nephel­ometric Turbidity Unit.
ppb Parts per billion: The equivalent of one second in 32 years.
ppm Parts per million: The equivalent of one second in 12 days.
ppt Parts per trillion: The equivalent of one second in 32,000 years.
pCi/L Picocuries per liter: The equivalent of one second in 32 million years.
Primary Standards: Federal drinking water regula­tions for substances that are health­-re­lated. Water suppliers must meet all primary drinking water standards.
Secondary Standards: Federal drinking water measur­ements for substances that do not have an impact on health. These reflect aesthetic qualities such as taste, odor and appear­ance. Secondary standards are recomm­end­ations, not mandates.
TON:Threshold Odor Number.
Treatment Technique (TT): A required process intended to reduce the level of a contam­inant in drinking


Concen­tration of hardness minerals
in grains per gallon (GPG)
Hardness Level
below 1.0
1.0 to 3.5
slightly hard
3.5 to 7.5
moderately hard
7.5 ti 10.5*
10.5 and above
very hard
* level at which most people find hardness object­ionable

General Water quality indicators

Aceptable Unit
pH value
6.5 to 8.5
An important overall measure of water quality, pH can alter corros­ivity and solubility of contam­inants. Low pH will cause pitting of pipes and fixtures or a metallic taste. This may indicate that metals are being dissolved. At high pH, the water will have a slippery feel or a soda taste.
<5 NTU
Clarity of sample can indicate contam­ina­tion.
Total Dissolved Solids (TDS)
500 mg/l
Dissolved minerals like iron or manganese. High TDS also can indicate hardness (scaly deposits) or cause staining, or a salty, bitter taste.

Common nuisance contam­inants and their effects

Acceptable Limit
250 mg/l
salty or brackish taste; corrosive; blackens and pits stainless steel
Copper (Cu)
1.3 mg/l
blue-green stains on plumbing fixtures; bitter metallic taste
Iron (Fe)
0.3 mg/l
metallic taste; discolored beverages; yellowish stains, stains laundry
Manganese (Mn)
0.05 mg/l or 5 ppb
black stains on fixtures and laundry; bitter taste
Sulfates (SO4)
250 mg/l
greasy feel, laxative effect
Iron Bacteria
orangeish to brownish slime in water

Natural or Bottled Water

Drinking water, including bottled water, may contain at least small amounts of some contam­inants. The presence of contam­inants does not necess­arily indicate that the water poses a health risk. More inform­ation about contam­inants and potential health effects can be obtained by calling the EPA Safe Drinking Water Hotline at 800.42­6.4791.

The sources of drinking water (for both tap and bottled water) include rivers, lakes, streams, ponds, reserv­oirs, springs and wells. As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals, and, in some cases, radioa­ctive material, and can pick up substances resulting from the presence of animals or human activity. Contam­inants that may be present in source water include:
Microbial contam­inants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricu­ltural livestock operat­ions, and wildlife.
Inorganic contam­inants, such as salts and metals, which can be natura­lly­-oc­curring or result from urban stormwater runoff, industrial or domestic wastewater discha­rges, oil and gas produc­tion, mining or farming.
Pesticides and herbicides, which may come from a variety of sources such as agricu­lture, urban stormwater runoff, and reside­ntial uses.
Organic chemical contam­inants, including synthetic and volatile organic chemicals, which are byproducts of industrial processes and petroleum produc­tion, and can also come from gas stations, urban stormwater runoff, and septic systems.
Radioa­ctive contam­inants, which can be natura­lly­-oc­curring or be the result of oil and gas production and mining activi­ties.

To ensure the water is safe to drink, the EPA regula­tions limit the amount of specific contam­inants allowed in public water systems. FDA regula­tions establish limits for contam­inants in bottled water to protect public health.
Bottom line? If bottled and tap water meet the federal standards, they are both safe to drink. However, your tap water is substa­ntially less expensive than bottled water.