Action Level - The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow. ALs are set by the USEPA. See also Unregulated Contaminants Rule

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Best Available Technology (BAT) - When regulators set an MCL, they consider the BAT. A cost-benefit analysis must be performed that compares the cost of treatment compared to the health benefits realized. BAT as identified by USEPA is a treatment technology that has high-removal efficiencies, is compatible with other types of water treatment processes, is commercially available, is not limited to use only in particular geographic regions, has integrity for a reasonable service life, is reasonably affordable by large MWD water systems, and can be mass-produced and put into service in time for implementation of regulations. [4]

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Carcinogen - a compound suspected or proven to cause cancer in humans. Research studies conducted to prove a constituent is a carcinogen are usually conducted on mice or rats. The compound is a ‘proven’ carcinogen when a percentage of the animals develop tumors, but it will be considered a “probable” or “possible” human carcinogen if limited or no human data are available.

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Chemical - Chemicals are composed of atoms that are chemically bonded to form molecules. Chemicals are often thought of as a "pure" substance. A pure chemical substance is separated from a mixture by physical means. A chemical reaction causes a chemical substance to change its identity.

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Contaminant - A chemical substance that is unwanted in water. Whether a contaminant is harmful depends on its concentration in water.

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Chemical Contaminants Rule - sets maximum contaminant limits (MCL) on over 65 contaminants that cause damage to human health. These contaminants can be categorized into three groups: volatile organic compounds (VOCs), synthetic organic compounds (SOCs), and inorganic compounds. [5]

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Chloramine - A combination of chlorine and ammonia, which is used as a disinfectant. Chloramine is an alternative approved disinfectant, which is less reactive with naturally occurring organic matter in water, forming fewer byproducts. [4]

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Concentration-  a comparison of the amount of a contaminant contained within a volume of water. Alternatively, concentration can compare the mass of contaminant with the mass of water.

 

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Contaminant - A polluting or poisonous substance. [11]

 

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Corrosion - A chemical reaction, usually with oxygen, that causes metal to rust.

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Detection Limit -  the lowest concentration of a contaminant that a given instrument or technique can measure. Each contaminant has a unique detection limit that is based on the best available technology. There are some contaminants that are so toxic that they may cause harm to human health in even smaller quantities than the detection limits. The detection limits are decided by the Division of Drinking Water (DDW). While laboratories in California are required to meet the detection limits, at LACWD we implement the latest technologies to detect even lower concentrations of high priority contaminants. See also: Non-Detect

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Disinfection - the removal of bacteria and viruses from water. Disinfection can be accomplished with chlorine, ozone, UV radiation, and other technologies.

 

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Disinfection Byproducts - Compounds that form when naturally occurring organic matter combines with chemicals used to disinfect drinking water, such as chlorine. Some disinfectants and disinfection byproducts (DBPs) have been shown to cause cancer and reproductive effects in lab animals and suggested bladder cancer and reproductive effects in humans. [3]

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Disinfection/ Disinfection Byproducts Rule - A rule created by the USEPA to  improve public health by reducing exposure to disinfection byproducts. Some disinfection byproducts (DBPs) have been shown to cause cancer and reproductive effects in lab animals and suggested bladder cancer and reproductive effects in humans. [3]

 

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Distribution Network - The underground network of pipes that delivers water to consumers. The distribution system consists of larger pipes called service mains, and smaller pipes, called service lines, that connect the mains to individual households.

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Division of Drinking Water (DDW)- A division of the  State Water Resources Control Board that regulates public drinking water systems.

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Emerging Contaminants - a class of contaminants that are unregulated. They may be new contaminants (e.g., MTBE) or those that may have been present but not detected (e.g., perchlorate). Other examples of these contaminants include pharmaceuticals and personal care products. Many of these contaminants can be classified also as VOCs and SOCs.

 

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Groundwater - water held underground in the soil or in pores and crevices in rock.

 

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Inorganic Compounds - a class of substances found in nature that do not pertain to living things. Inorganic compounds do not contain the element carbon, with some exceptions. Examples of inorganic compounds include water, carbon dioxide, minerals, clay, sand, rocks, and dissolved salts.  See also: Organic Compounds

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Lead and Copper Rule - The treatment technique for the rule requires systems to monitor drinking water at customer taps. If lead concentrations exceed an action level of 15 ppb or copper concentrations exceed an action level of 1.3 ppm in more than 10% of customer taps sampled, the system must undertake a number of additional actions to control corrosion. [13] Learn more about the Lead and Copper Rule

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Los Angeles County Waterworks Districts (LACWD) - A coalition of five water districts that provides water to retail water service to Kagel Canyon, Malibu, Val Verde, Acton, and the Antelope Valley. These are suburbs of the City of Los Angeles.

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Los Angeles Department of Water and Power (LADWP) - the largest municipal water and power utility in the nation. LADWP provides services to 681,000 water customers and 1.4 million electric customers.

 

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Lead Service Line - Service lines connect homes and businesses to the public water main. Starting in the 1920's and ending in 1986, lead was a common material for service lines. After the discovery that lead is an extremely toxic material, lead service lines were banned in new construction. It is estimated that millions of lead service lines are still in use today across the United States. Learn about what we're doing to remove lead service lines.

 

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Maximum Contaminant Level (MCL) - The enforceable drinking water standard set by either the USEPA or the DDW. MCLs are based on the lowest observed health effects level plus a margin of safety and the current technology available to detect and treat the constituent. USEPA can set a treatment technique instead of an MCL for compounds that are difficult to monitor or are affected by conditions in the distribution system. [4]

 

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Maximum Contaminant Level Goal (MCLG) - The MCLG is the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows a margin of safety. MCLGs are not enforceable by law. MCLGs are set by the USEPA.  [4]

 

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Non-Detect - We can never say that there is zero concentration of a contaminant in water. This is because no measuring instrument is perfect; they all have a lower bound. For common water quality indicators, there is almost always some tiny amount of the contaminant in water. However,  due to random noise that comes from the environment, the signal from the instrument is drowned out and indistinguishable. In this situation, we say Non-Detect (ND) because our instrument was not able to detect any level of the contaminant. See also: Detection Limit

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Notification Level - Notification levels are health-based advisory levels established by the Division of Drinking Water (DDW) for chemicals in drinking water that lack maximum contaminant levels (MCLs). When chemicals are found at concentrations greater than their notification levels, certain requirements and recommendations apply. The level at which DDW recommends removal of a drinking water source from service is called the "response level." [9]

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Organic Compound- material that is related to or derived from living matter. Organic material contains the element carbon. See also: VOC; SOC

 

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Parts Per Billion (ppb) - A unit of measure that compares the amount of mass of a pollutant compared to one billion units of mass of water. See also Understanding Units of Measure

 

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Parts per million (ppm) - A unit of measure that compares the amount of mass of a pollutant compared to one million units of mass of water. See also Understanding Units of Measure

 

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Pathogen - a bacterium, virus, or other microorganism that can cause disease. [11]

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Picocurie per Liter (pCi/L) - The curie is a standard measure for the intensity of radioactivity contained in a sample of radioactive material. The basis for the curie is the radioactivity of one gram of radium. One picocurie (abbreviated as pCi) represents 2.2 disintegrations per minute.

 

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Primary Drinking Water Standards - A set of contaminants that can cause health impacts to humans. The USEPA sets limits (MCL) for how much of each contaminant can be present in water. Water treatment utilities are required by law to remove these contaminants to concentrations below the MCL.  Learn more about Primary Drinking Water Standards

 

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Public Health Goal (PHG) - A PHG is the level of a chemical contaminant in drinking water that does not pose a significant risk to health. PHGs are not regulatory standards. However, state law requires SWRCB to set primary drinking water standards for chemical contaminants as close to the corresponding PHG as is economically and technologically feasible. In some cases, it may not be feasible for SWRCB to set the drinking water standard for a contaminant at the same level as the PHG. The technology to treat the chemicals may not be available, or the cost of treatment may be very high. SWRCB must consider these factors when developing a drinking water standard. Learn more about Public Health Goals. [1]

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Radionuclides - Substances that are radioactive. A nuclide is an atom or nucleus that has a distinct number of protons and neutrons. A radionuclide is a nuclide that has an unstable configuration and so breaks down to emit ionizing radiation or particles.

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Radionuclides Rule - A regulation set by the USEPA that limits the concentration of radionuclides in water. 

 

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Secondary Drinking Water Standards - A set of contaminants that cause aesthetic (taste, odor and color) issues in water. The USEPA sets limits Secondary Maximum Contaminant Limits (SMCL) for how much of each contaminant can be present in water. Water treatment utilities are encouraged but not required to remove these contaminants to concentrations below the MCL. These contaminants are not considered to present a risk to human health at the SMCL. [10]

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State Water Resource Control Board (SWCB) - is the regulatory agency with the authority to set and enforce drinking water standards for the state. It may maintain standards at levels set by U.S. EPA, or it may set more stringent standards. Through its Division of Drinking Water, SWRCB works with county health departments to license and monitor public water systems. [1]

 

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Surface Water - Water on the ground surface including streams, rivers, ponds, lakes, wetlands, reservoirs among others.

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Surface Water Treatment Rule - The purpose of the Surface Water Treatment Rules (SWTRs) is to reduce illnesses caused by pathogens in drinking water. The disease-causing pathogens include Legionella, Giardia lamblia, and Cryptosporidium. [2]

 

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Synthetic Organic Compounds - a class of man-made contaminants that are not normally found in nature This group includes herbicides, pesticides, pharmaceuticals, personal care products and chemicals used in industry. Learn more about synthetic organic compounds. [7]

 

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Toxicity - The degree to which a substance (a toxin or poison) can harm humans or animals. Acute toxicity occurs when a large amount of the toxin is exposed over a short time period. Chronic toxicity is when lower doses are exposed over a longer period of time. Health effects on humans are different depending on acute or chronic exposure.

 

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Treatment Technique (TT) - A required practice intended to reduce the level of a contaminant in drinking water that is set by USEPA for contaminants that are difficult or costly to measure. For these contaminants, USEPA may choose a specific water treatment practice (such as filtration or corrosion control) to reduce these contaminants. The treatment technique is used instead of setting an MCL for these contaminants. [4]

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United States Environmental Protection Agency (USEPA) - An agency of the federal government that is responsible for the protection of the environment.

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Unregulated Contaminants - chemicals in drinking water that lack maximum contaminant levels (MCLs), but that are suspected of causing harm to human health. The California DDW specifies which unregulated contaminants that water utilities must monitor for. If the concentration of a contaminant is found to be above the Notification Level (NL),  the utility must report it to their consumers. 

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Volatile Organic Compounds (VOC) - are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. VOCs typically are industrial solvents, such as trichloroethylene; fuel oxygenates, such as methyl tert-butyl ether (MTBE); or by-products produced by chlorination in water treatment, such as chloroform. VOCs are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning agents. VOCs are common groundwater contaminants. [8] Learn More about VOCs

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Sources

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1. Guide to Public Health Goals for Chemicals in Drinking Water. (2015). California Office of Environmental Health and Hazard Assessment. 1. https://oehha.ca.gov/water/guide-public-health-goals-chemicals-drinking-water

2. Surface Water Treatment Rules | Drinking Water Requirements for States and Public Water Systems | US EPA. (2015, October 13). US EPA. http://www.epa.gov/dwreginfo/surface-water-treatment-rules

3. Comprehensive Disinfectants and Disinfection Byproducts Rules Quick Reference Guide. (2010). https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100C8XW.txt

4. LADWP - About Us. (n.d.). Retrieved December 2, 2020, from https://www.ladwp.com/cs/idcplg?

5. Chemical Contaminant Rules | Drinking Water Requirements for States and Public Water Systems | US EPA. (2015, October 13). US EPA. http://www.epa.gov/dwreginfo/chemical-contaminant-rules

6. Volatile Organic Chemical Contaminants | Florida Department of Environmental Protection. (n.d.). Welcome to Florida Department of Environmental Protection. Retrieved December 2, 2020, from http://floridadep.gov/water/source-drinking-water/content/volatile-organic-chemical-contaminants

7. Synthetic Organic Contaminants and their Standards | Florida Department of Environmental Protection. (n.d.). Welcome to Florida Department of Environmental Protection. Retrieved December 2, 2020, from http://floridadep.gov/water/source-drinking-water/content/synthetic-organic-contaminants-and-their-standards

8. What are volatile organic compounds (VOCs)? | Indoor Air Quality (IAQ) | US EPA. (2019, February 19). US EPA. http://www.epa.gov/indoor-air-quality-iaq/what-are-volatile-organic-compounds-vocs#:~:text=Volatile%20organic%20compounds%20(VOCs)%20are,ten%20times%20higher)%20than%20outdoors.

9. Drinking Water Notification Levels | California State Water Resources Control Board. (n.d.). Home Page | California State Water Resources Control Board. Retrieved December 2, 2020, from http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NotificationLevels.html

10. Secondary Drinking Water Standards: Guidance for Nuisance Chemicals | Safe Drinking Water Act (SDWA) | US EPA. (2015, September 2). US EPA. http://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals

11. New Oxford American Dictionary. (n.d.).

12. Emerging Contaminants | California State Water Quality Control Board. (n.d.). Home Page | California State Water Resources Control Board. Retrieved December 2, 2020, from http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/EmergingContaminants.html

13. Lead and Copper Rule | Drinking Water Requirements for States and Public Water Systems | US EPA. (2015, October 13). US EPA. http://www.epa.gov/dwreginfo/lead-and-copper-rule

14. How Big is a Pico Curie. (n.d.). US Army Corps of Engineers. Retrieved December 2, 2020, from www.lrb.usace.army.mil/Portals/45/docs/FUSRAP/FactSheets/fusrap-fs-picocurie.pdf  ​

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