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1.9: Primary Standards

  • Page ID
    6980
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    Learning Objectives

    • Define primary standards
    • Describe the primary metal contaminates
    • Describe the primary organic contaminates
    • Describe the primary synthetic organic contaminates
    • Describe sampling guidelines
    • Describe the Radiologic Rule
    • Describe the Total Coliform Rule

    Federal (Environmental Protection Agency, EPA)

    The process by which EPA sets drinking water standards is long and complicated. It involves deciding which contaminants may endanger public health, conducting studies of the effects of these contaminants, defining the maximum safe level of each contaminant, estimating the costs and benefits of regulation, proposing a standard or limit, listening to and evaluating public reactions to the proposed standard, revising the standard (if needed), proposing the standard in final form, seeking and evaluating additional public input, and finally, publishing the standard. The primary standards are referred to as the Maximum Contaminate Level (MCL). This level is not considered to effect a person’s health with a margin of safety. However, when the level of a contaminant is above the MCL, it is considered to be a health hazard. MCLs are enforceable by law.

    The entire process by which a standard is proposed and promulgated is governed by strict procedural guidelines. It often takes three or more years to produce a standard.

    Types of Contaminants

    Five types of primary contaminants are considered to be of public health importance:

    • Inorganic contaminants, such as lead and mercury
    • Organic contaminants, which include pesticides, herbicides, THMs, solvents, and other synthetic organic compounds
    • Turbidity, such as small particles suspended in water that interfere with light penetration and disinfection
    • Microbial contaminates, such as bacteria, viruses, and protozoa
    • Radiologic contaminates, which include natural and manmade sources of radiation

    Identifying Contaminants to Be Regulated

    The 1986 SDWA required EPA to establish a priority list of contaminants that may have adverse health effects and may require regulation. The 1996 SDWA amendments retained the list of 83 contaminants developed earlier but revised the process by which contaminants are selected for regulation. Before selecting a contaminant for regulation, the EPA must now consult with the scientific community, solicit public comments, and demonstrate that the contaminant actually occurs in public water systems. For this latter purpose, the 1996 amendments required EPA to establish an occurrence database by August 1999. The database contains information concerning regulated and unregulated contaminants and the information is available to the public.

    To regulate a substance, EPA must demonstrate that the contaminant meets three criteria:

    • The contaminant has an adverse effect on human health
    • It occurs, or is likely to occur, in public water systems at a frequency and concentration of significance to public health
    • Regulation of the contaminant offers a meaningful opportunity to reduce health risks for people served by public water systems

    In addition to meeting these three criteria, EPA must also weigh the relative health risks of various contaminants being considered for regulation, the risk reduction that regulation would accomplish, and the costs of implementing the regulations.

    Working on a 5-year cycle, the EPA is required to select at least five contaminants from its Drinking Water Contaminant Candidate List (DWCCL) and decide whether sufficient reason exists to regulate them. The first DWCCL included 50 chemicals and 10 microbial contaminants. In June 2002, the EPA announced a preliminary finding that their research revealed no need to regulate ten of the listed contaminants. Based on public comments and continued research and evaluation, EPA will make a final determination about regulating any of these contaminants and will begin to develop proposed regulations as necessary.

    Unregulated Contaminants

    EPA uses the Unregulated Contaminant Monitoring (UCM) program to collect data for contaminants suspected to be present in drinking water, although they do not have health-based standards set under the SDWA. Every 5 years, EPA reviews the list of contaminants, largely based on the Contaminant Candidate List.

    The SDWA Amendments of 1996 provide for the following:

    • Monitoring no more than 30 contaminants per 5-year cycle
    • Monitoring only a representative sample of public water systems
    • serving fewer than 10,000 people
    • Storing analytical results in a National Contaminant Occurrence Database (NCOD)

    The UCM program has progressed in several stages. Currently, EPA manages the program directly as specified in the Unregulated Contaminant Monitoring Regulation (UCMR). EPA has established a timeline and plans for monitoring unregulated contaminants through 2015.

    Under the UCMR, community water systems and non-transient non-community water systems serving more than 10,000 people are required to monitor for unregulated contaminants; smaller systems may also have to conduct monitoring if required by the state. Transient water systems are not affected by the UCMR.

    Always keep in mind that EPA’s regulatory process is basically just a process. No list is permanent; regulations change frequently as new information becomes available. Water treatment plant operators must continually seek opportunities to learn about the regulations that affect the water industry. Also, operators should feel free to express their concerns regarding the regulations and the regulatory process to EPA.

    Primary Standards

    Inorganic chemicals are metals, salts, and other chemical compounds that do not contain carbon. The health concerns about inorganic chemicals are not centered on cancer, but rather on their suspected links to several different human disorders. For example, lead is suspected of contributing to mental retardation in children. Waters exceeding the MCL for these elements for short periods of time will pose no immediate threat to health. However, studies show that these substances must be controlled because the consumption of drinking water that exceeds these standards over long periods of time may prove harmful.

    Antimony

    In the Code of Federal Regulations Reference: 40 CFR 721.1930, antimony is used in the production of ceramics, glassware, and pigments. The major sources of antimony in drinking water are discharged from petroleum refineries, fire retardants, ceramics, electronics, and solder. Most exposures to antimony occur in industrial settings where workers may inhale dust containing particles of the metal.

    To reference the CA Regulations visit: www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/arsenic/DPH-17-04-FinalRegText.pdf.

    Purpose of Regulating Antimony: To improve public health protection by reducing exposure to the amount of antimony in drinking water.

    Public Health Benefit: Some people who drink water containing antimony well in excess of the MCL for many years could experience increases in blood cholesterol and decreases in blood sugar. Ingestion of antimony can alter cholesterol and glucose levels and may cause chromosome damage.

    MCL/MCLG: 0.006 mg/L/0.006 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Arsenic

    In the Code of Federal Regulations Reference: 40 CFR 141 Subpart B. arsenic occurs naturally in the environment, especially in the western United States, and it is used in insecticides. Arsenic is found in foods, tobacco, shellfish, drinking water, and in the air in some locations. Anyone who drinks water that continuously exceeds the national standard by a substantial amount over a lifetime may experience fatigue and loss of energy. Extremely high levels of arsenic can cause poisoning.

    The regulation of arsenic has been vigorously debated. In 1997, EPA released a health effects study plan. Under this plan, EPA worked with the Water Research Foundation (WRF) and the Association of California Water Agencies to assess the health risks from exposure to low levels of arsenic. Based on the results of these studies, EPA proposed an MCL for arsenic in June 2000, and a final rule was issued on January 22, 2001. Technologies available for removing arsenic include ion exchange, iron hydroxide coagulation followed by microfiltration and activated alumina.

    Purpose of Regulating Arsenic: To improve public health protection by reducing exposure to arsenic in drinking water.

    Public Health Benefit: The avoidance of bladder and lung cancer, dental problems, and a reduction in the frequency of non-carcinogenic diseases.

    MCL/MCLG: 0.010 mg/L/zero

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Asbestos

    In the Code of Federal Regulations Reference: 40 CFR 141.62, the general term asbestos refers to a family of fibrous silicate minerals that have been widely used in the manufacture of commercial products. Some examples of products containing asbestos include floor and ceiling tiles, paper products, paint and caulking, plastics, brake linings, insulation, cement, and filters.

    Asbestos in cement pipes is a potential source of contamination of drinking water. Deterioration of this material with age and exposure to corrosive water is thought to release asbestos particles. Mining for asbestos minerals has also contributed to the contamination of some drinking water sources throughout the United States. Scientific evidence on the harmful effects of asbestos consumed in drinking water is less conclusive than the evidence relating to inhaled asbestos.

    Purpose of Regulating Asbestos: To improve public health protection by reducing exposure to asbestos in drinking water.

    Public Health Benefit: To reduce the risk of developing benign intestinal polyps.

    MCL/MCLG: 7 million fibers per liter (MFL)/7 MFL

    Monitoring Requirements: Once every 9 years.

    Barium

    Code of Federal Regulations Reference: 40 CFR 141.62, although not as widespread as arsenic, this element also occurs naturally in the environment in some areas of the US. Barium can also enter water supplies through industrial waste discharges. Small doses of barium are not harmful. However, it is quite dangerous when consumed in large quantities and will bring on increased blood pressure, nerve damage, and death.

    Purpose of Regulating Barium: To improve public health protection by reducing exposure to large quantities of barium in drinking water.

    Public Health Benefit: To reduce the risk of high blood pressure.

    MCL/MCLG: 2 mg/L/2 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Beryllium

    In the Code of Federal Regulations Reference: 40 CFR 141.62, the major source of beryllium in the environment is the combustion of coal and oil. Airborne particulates containing beryllium can be inhaled or washed by precipitation into drinking water supplies. Animal studies show that when large doses of beryllium are ingested, it is carried by the bloodstream from the stomach to the liver; however, it is gradually transferred to the animal’s bones.

    Purpose of Regulating Beryllium: To improve public health protection by reducing exposure to large quantities of beryllium in drinking water.

    Public Health Benefit: To reduce the risk of intestinal lesions.

    MCL/MCLG: 0.004 mg/L/0.004 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Bromate

    In the Code of Federal Regulations Reference: 40 CFR Parts 9, 141, and 142, bromate is formed as a byproduct of ozone disinfection of drinking water. Ozone reacts with the naturally occurring bromide ion in the water to form bromate. Bromate is an inorganic ion that is tasteless, colorless, and has low volatility. Bromate dissolves easily in water and is fairly stable. Bromate is not typically derived from natural sources. It is commonly found in raw water supplies such as streams, lakes, and reservoirs.

    Purpose of Regulating Bromate: To improve public health protection by reducing exposure to bromate in drinking water.

    Public Health Benefit: To reduce the risk of cancer.

    MCL/MCLG: 0.010 mg/L/zero

    Monitoring Requirements: Monthly (ozone systems only).

    Cadmium

    In the Code of Federal Regulations Reference: 40 CFR 141.62, only extremely small amounts of cadmium are found in natural waters in the United States. Waste discharges from the electroplating, photography, insecticide, and metallurgy industries can increase cadmium levels. The most common source of cadmium in drinking water is from galvanized pipes and fixtures.

    Purpose of Regulating Cadmium: To improve public health protection by reducing exposure to cadmium in drinking water.

    Public Health Benefit: To prevent kidney damage.

    MCL/MCLG: 0.005 mg/L/0.005 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Chlorite

    In the Code of Federal Regulations Reference: 40 CFR Parts 9, 141,and 142, the main source of chlorite in drinking water is chlorine dioxide used for disinfection. Chlorite forms as the chlorine dioxide breaks down during the disinfection process. Chlorite is an inorganic ion that is colorless, odorless, tasteless, and dissolves easily in water. Chlorite is one of the two or three chemicals involved in the process of generating chlorine dioxide for water treatment.

    Chlorite is not typically derived from natural sources.

    Purpose of Regulating Chlorite: To improve public health protection by reducing exposure to chlorite in drinking water, especially for infants and young children.

    Public Health Benefit: To prevent adverse effects of the nervous system and anemia.

    MCL/MCLG: 1.0 mg/L/0.8 mg/L

    Monitoring Requirements: For systems that add chlorine dioxide, daily samples are required at distribution system entry points.

    Chromium

    In the Code of Federal Regulations Reference: 40 CFR 141.62, chromium is found in cigarettes, some foods, and the air. It is also discharged from steel and pulp mills and the erosion of natural deposits. Some studies suggest that in very small amounts, chromium may be essential to human beings, but it has not been proven.

    Purpose of Regulating Chromium: To improve public health protection by reducing exposure to chromium in drinking water.

    Public Health Benefit: To prevent allergic dermatitis.

    MCL/MCLG: 0.1 mg/L/0.1 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Copper

    In the Code of Federal Regulations Reference: 40 CFR 141.86, copper in drinking water usually results from the reaction of water on copper plumbing. Treatment of surface water in storage reservoirs to control algae may also cause high levels of copper. Copper is an essential nutrient; adults require 2 mg daily and children of preschool age require about 0.1 mg daily for normal growth.

    The presence of copper in drinking water is also undesirable because of its aesthetic effects. At low levels (0.5 mg/L in soft waters) blue or blue-green staining of porcelain occurs. At higher levels (4 mg/L), it will stain clothing and blond hair. Concentrations greater than 1 mg/L can produce insoluble green curds when reacting with soap.

    The primary standard for copper includes a treatment technique of the taps sampled exceed the action level (AL) of 1.3 mg/L.

    Action levels communicate health or physical hazards by categorizing these hazards into levels. Action levels are used by OSHA and NIOSH to determine how harmful a substance or activity is.

    Purpose of Regulating Copper: To improve public health protection by reducing water corrosivity.

    Public Health Benefit: To prevent gastrointestinal, kidney, and liver problems.

    MCL/MCLG: A treatment technique (TT) is triggered at AL = 1.3 mg/L/1.3 mg/L

    Monitoring Requirements: Residential sample taken at the kitchen or bathroom sink tap. ALs must be met in 90 percent of the samples. Follow-up monitoring every 6 months after corrosion controls initiated or optimized. Reduced monitoring for systems consistently meeting AL.

    Cyanide

    In the Code of Federal Regulations Reference: 40 CFR 141.62, cyanide is a common ingredient of rat poisons, silver and metal polishes, and photo processing chemicals. The major source of cyanide in drinking water is discharge from industrial chemical factories.

    Ingestion of even very small amounts of sodium cyanide or potassium cyanide can cause death within a few minutes to a few hours. Typical symptoms of cyanide poisoning include nausea without vomiting, anxiety, vertigo, lower jaw stiffness, convulsions, paralysis, irregular heartbeat, and coma.

    Purpose of Regulating Cyanide: To improve public health protection by reducing long-term exposure to cyanide.

    Public Health Benefit: To prevent thyroid/neurological damage.

    MCL/MCLG: 0.2 mg/L/0.2 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Fluoride

    In the Code of Federal Regulations Reference: 40 CFR 141.62, fluoride is a natural mineral and many sources of drinking water contain some fluoride. Fluoride produces two effects, depending on its concentration. EPA has set primary and secondary limits to regulate it. Many communities add fluoride to their drinking water to promote dental health. The decision to fluoridate a water supply is made by the state or local municipality, and is not mandated by EPA or any other federal entity.

    However, EPA has completed and peer-reviewed a quantitative dose-response assessment based on the available data for severe dental fluorosis as recommended by the National Research Council (NRC). At levels of 6 to 8 mg/L, fluoride may cause brittle bones and stiffening of the joints. On the basis of this health hazard, fluoride has been added to the list of primary standards.

    At levels of 2 mg/L and greater, fluoride may cause dental fluorosis, which is discoloration and mottling of the teeth, especially in children. EPA has reclassified dental fluorosis as a cosmetic effect, raised the primary drinking water standard from 1.4–2 mg/L to 4 mg/L, and established a secondary standard of 2 mg/L for fluoride.

    Purpose of Regulating Fluoride: To improve public health protection by preventing long-term exposure to fluoride.

    Public Health Benefit: To prevent bone disease.

    MCL/MCLG: 4.0 mg/L/4.0 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Lead and Copper

    The Code of Federal Regulations Reference: 40 CFR 141 Subpart I, is concerned with the control of lead and copper. Basic Requirements of the Lead and Copper Rule (LCR) are:

    • Require water suppliers to optimize their treatment system to control corrosion in customers’ plumbing.
    • Determine tap-water levels of lead and copper for customers who have lead service lines or lead-based solder in their plumbing system.
    • Rule out the source water as a source of significant lead levels.
    • If lead ALs are exceeded, require the suppliers to educate their customers about lead and suggest actions they can take to reduce their exposure to lead through public notices and public education programs. If a water system, after installing and optimizing corrosion control treatment, continues to fail to meet the lead AL, it must begin replacing the lead service lines under its ownership.

    Revisions to the Lead and Copper Rule (LCR)—EPA is promulgating a rule that makes several targeted regulatory revisions to the existing national primary drinking water regulations.

    (NPDWRs) for lead and copper. The revisions to the LCR will do the following:

    • Enhance the implementation of the LCR in the areas of monitoring, treatment, customer awareness, and lead service line replacement
    • Improve compliance with the public education requirements of the LCR to ensure drinking water consumers receive meaningful, timely, and useful information needed to help them limit their exposure to lead in drinking water

    Lead is a naturally occurring metal that was used regularly in a number of industrial capacities and commonly used in household plumbing materials and water service lines. Lead was used as a component of paint, piping, solder, brass, and as a gasoline additive until the 1980s. The greatest exposure to lead is swallowing or breathing it in lead paint chips and dust. Research has confirmed that lead is highly toxic.

    Lead is rarely found in source water. Mostly, lead contamination occurs after water has left the treatment plant due to the corrosion of plumbing materials. Since water is naturally corrosive, it corrodes the pipes and plumbing through which it passes. Homes built before 1986 are more likely to have lead pipes, fixtures, and solder. However, new homes are also at risk because even legally lead-free plumbing may contain up to 8-percent lead. Grounding of electrical circuits in homes to water pipes and galvanic action between two dissimilar metals may increase corrosion that could cause lead to leach into the water.

    Purpose of Regulating Lead: To protect public health by minimizing lead levels in drinking water, primarily by reducing water corrosivity.

    Public Health Benefit: To prevent kidney problems, high blood pressure, and delays in physical and mental development in infants and children.

    MCL/MCLG: A TT is triggered at AL = 0.015 mg/L/zero

    Monitoring Requirements/Comments: Residential samples taken at the kitchen or bathroom sink tap. ALs must be met in 90 percent of the samples. Follow-up monitoring every 6 months after corrosion controls initiated or optimized. Reduced monitoring requirements for systems consistently meeting the AL. An AL exceedance is not a violation but can trigger other requirements that include monitoring for the following water quality indicators: pH, corrosion, control treatment, source water monitoring/treatment, public education, and lead service line replacement.

    Copper is a metal found in natural deposits such as ores containing other elements. Copper is widely used in household plumbing materials.

    Purpose of Regulating Copper: To protect public health by minimizing the risk of ingesting copper in drinking water, primarily from the corrosion of pipes.

    Public Health Benefit: To prevent gastrointestinal distress due to short-term exposure and to prevent liver or kidney damage from long-term exposure.

    MCL/MCLG: A TT is triggered at AL = 1.3 mg/L/1.3 mg/L

    Monitoring Requirements/Comments: Residential samples taken at the kitchen or bathroom sink tap. ALs must be met in 90 percent of the samples. Follow-up monitoring every 6 months after corrosion controls initiated or optimized. There are reduced monitoring requirements for systems consistently meeting the AL. An AL exceedance is not a violation but can trigger other requirements that include monitoring for the following water quality indicators: pH, corrosion control treatment, source water monitoring/treatment, public education, and lead service line replacement.

    All water systems are required to optimize corrosion control; that is to say, they must do the best they can to control corrosion. Small- and medium-sized systems are considered to have optimized corrosion control if they meet the lead and copper action levels during each of two consecutive six-month sampling periods. Large systems have optimized corrosion control if the difference between the source water lead level and the 90th percentile tap-water lead level is less than 0.005 mg/L, and the 90th percentile copper concentration is less than or equal to half the copper action level (0.65 mg/L) for two consecutive six-month periods.

    Any system that is achieving optimal corrosion control and meeting the action limits is permitted to reduce monitoring and reporting frequencies. Large water systems that do not meet the guidelines for optimal corrosion control are required to conduct studies of various types of corrosion control treatment and then submit to the state a plan that would adequately control corrosion in their distribution system.

    Small- and medium-sized systems exceeding the action levels must make a written recommendation to the state for a proposed treatment method, but may also be required to conduct similar studies before the state makes a final determination.

    Once the state directs a water supplier to install treatment, the agency has 24 months to install the specified treatment and 12 months to collect follow-up samples to determine if the system is working. The state will also determine maximum acceptable levels for pH, alkalinity, calcium (if carbonate stabilization is used), orthophosphate (if an inhibitor with a phosphate compound is used), and silica (if an inhibitor with a silicate compound is used). The system must then continue to operate within these water quality guidelines.

    If corrosion control methods fail to reduce lead and copper concentrations below the action levels, the water supplier must collect and analyze source water samples. Data from this sampling is sent to the state along with the water agency’s recommended treatment plan for reducing contaminant levels. The state may accept the agency’s recommended plan or may require some alternative treatment such as ion exchange, reverse osmosis, lime softening, or coagulation-filtration.

    When required to install source water treatment, the agency is allowed 24 months for installation and 12 months to collect follow-up samples of specific water quality indicators. Based on the results of the follow-up sampling, the state determines the maximum allowable source water lead and copper concentrations and the water system is required to meet these state limits on an ongoing basis.

    Water systems that continue to exceed the lead action level after installing optimal corrosion control treatment and source water treatment will have to begin a program to replace lead service lines within a maximum of 15 years.

    Sampling Guidelines

    The sampling required by the Lead and Copper Rule includes tap-water sampling at the consumer’s faucet and distribution system sampling. Tap-water samples for initial and routine lead and copper monitoring must be collected at high-risk locations, which are defined as homes with lead solder installed after 1982, homes with lead pipes, and homes with lead service lines.

    Tap-water samples for water quality indicators should be taken from representative taps throughout the distribution system. The representative taps can be the same as total coliform sampling sites. These samples will be analyzed for water quality indicator levels to identify optimal treatment and monitor compliance with the rule.

    The rule calls for first-draw or first-flush samples, which are water samples taken after the water stands motionless in the plumbing pipes for at least six hours. This rule usually means taking a sample early in the day before water is used in the kitchen or bathroom. The rule permits water utilities to instruct consumers in sampling techniques so that they may collect the samples.

    One-liter samples are needed.

    Distribution system sampling conducted in connection with corrosion control studies requires samples from representative taps throughout the system as well as samples from entry points to the distribution system.

    Initial and Base Monitoring Sample Sites

    Compliance with the Lead and Copper Rule depends on meeting the action levels during two consecutive six-month monitoring periods. All public water systems are required to collect one sample for lead and copper analysis from a number of sites depending on population during each six-month monitoring period.

    If a system meets the lead and copper action levels or maintains optimal corrosion control treatment for two consecutive six-month periods, tap-water sampling for lead and copper can be reduced to once per year and half the number of sites. After three consecutive years of acceptable performance, tap-water sampling can be reduced to once every three years at the reduced number of sites listed above.

    Water Quality Indicator Frequency

    All large systems (more than 50,000 persons) and any small- or medium-sized system that exceeds the lead or copper action level will be required to monitor for the following water quality indicators: pH, alkalinity, calcium, conductivity, orthophosphate, silica, and water temperature. Samples must be taken from representative taps throughout the system and at entry points to the distribution system. Two tap-water samples must be collected for each applicable water quality indicator.

    In addition to the sampling from representative taps, one sample must be collected every two weeks for each applicable water quality indicator at each entry point to the distribution system.

    All large water systems and any small- and medium-sized system that exceed the lead or copper action levels after installing optimal corrosion control treatment must continue to collect samples as follows:

    1. 2 samples for each applicable water quality indicator at each of the sampling sites (taps) every 6 months.
    2. 1 sample for each applicable water quality indicator at each entry point to the distribution system every 2 weeks.
    3. After meeting water quality guidelines for 2 consecutive 6-month monitoring periods, systems may reduce the number of tap samples collected, and after 3 consecutive years of acceptable performance they will be permitted to collect annual samples at the reduced number of sampling points.

    Calculation of the 90th Percentile

    The action levels that trigger implementation of treatment techniques to reduce lead and copper concentrations are based on the principle that no more than 10 percent of the samples should exceed the limit. To determine whether a system meets this test, it is necessary to figure out the lead or copper concentration on the sample that falls at the 90th percentile.

    To calculate the 90th percentile value, write down the results from a set of samples arranging them in order of increasing or decreasing concentration. Number each sample beginning with the number 1 for the smallest concentration. Multiply the total number of samples (which will be the same as the number assigned to the highest concentration) by 0.9. Then, use the value from this calculation to identify the sample with the same number.

    The concentration of the sample whose number matches the calculated value is the 90th percentile and is used in determining compliance with the action level. For systems serving fewer than 100 people, the 90th percentile is the average of the highest concentration and the second highest concentration.

    Public Education

    A public education program developed by the EPA must be delivered to water system customers within 60 days whenever the system exceeds the lead or copper action levels. The information describes the harmful effects of lead in drinking water and tells customers what they can do to reduce their exposure. The education program should continue as long as the system fails to meet the lead or copper action levels. In conjunction with the public education program, the water system must offer to sample a customer’s water if asked to do so. However, the water system is not required to pay for the sampling and analysis and is not required to collect and analyze the sample.

    Lead Service Line Replacement

    Any water system that continues to exceed the lead and copper action levels even after optimizing corrosion control and installing source water treatment will be required to replace its lead distribution pipes within a maximum of 15 years. A lead pipeline qualifies for replacement if it contributes more than 15 parts per billion to the total tap-water lead levels. Seven percent of the lines meeting this standard must be replaced annually. Customers must be notified 45 days before replacing the lines.

    Mercury

    In the Code of Federal Regulations Reference: 40 CFR 141.62, mercury is found naturally throughout the environment. Large increases in mercury levels in water can be caused by industrial and agricultural use. The health risk from mercury is greater from mercury in fish than simply from waterborne mercury.

    Mercury poisoning may have an acute health effect in large doses, or a chronic health effect in lower doses taken over an extended time period.

    Purpose of Regulating Mercury: To improve public health protection and reduce ingestion of mercury.

    Public Health Benefit: To prevent kidney damage.

    MCL/MCLG: 0.002 mg/L/0.002 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Nitrate

    In the Code of Federal Regulations Reference: 40 CFR 141.62, nitrate (as N) in drinking water above the national standard of 10 mg/L poses an immediate threat to children under three months of age. In some infants, excessive levels of nitrate have been known to react with intestinal bacteria that change nitrate to nitrite. It is often difficult to pinpoint sources of nitrate because so many possibilities exist.

    Sources of nitrogen may include runoff or seepage from fertilized agricultural lands, municipal and industrial wastewater, refuse dumps, animal feedlots, septic tanks and private sewage disposal systems, urban drainage, and decaying plant debris.

    Purpose of Regulating Nitrate: To improve public health protection.

    Public Health Benefit: To prevent methemoglobinemia (blue baby syndrome)/diuresis.

    MCL/MCLG: 10 mg/L/10 mg/L

    Monitoring Requirements: Groundwater annually; surface water quarterly initially, then annually.

    Nitrite

    Code of Federal Regulations Reference: 40 CFR 141.62, nitrite reacts with hemoglobin in the blood. This reaction will reduce the oxygen-carrying ability of the blood and produce an anemic condition commonly known as blue baby syndrome. Sources of nitrite may include runoff or seepage from fertilized agricultural lands, municipal and industrial wastewater, refuse dumps, animal feedlots, septic tanks and private sewage disposal systems, urban drainage, and decaying plant debris.

    Purpose of Regulating Nitrite: To improve public health protection.

    Public Health Benefit: To prevent methemoglobinemia (blue baby syndrome)/diuresis.

    MCL/MCLG: 1 mg/L/1 mg/L

    Monitoring Requirements: One sample during first 3-year compliance period. Repeat frequency determined by state.

    Selenium

    In the Code of Federal Regulations Reference: 40 CFR 141.62, this mineral occurs naturally in soil and plants, especially in western states. Selenium is found in meat and other foods. Although it is believed to be essential in the diet, indications exist that excessive amounts of selenium may be toxic.

    Studies are underway to determine the amount required for good nutrition and the amount that may be harmful. If a person’s intake of selenium came only from drinking water, it would take an amount many times greater than the standard to produce any ill effects.

    Purpose of Regulating Selenium: To improve public health protection.

    Public Health Benefit: To prevent hair or fingernail loss, numbness of fingers or toes, and circulatory problems.

    MCL/MCLG: 0.05 mg/L/0.05 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Thallium

    In the Code of Federal Regulations Reference: 40 CFR 141.62, thallium is a metal found in natural deposits such as ores containing other elements. The major sources of thallium in drinking water are leaching from ore-processing sites and discharge from electronics, glass, and drug factories. Thallium is an extremely toxic metal that is used in refining iron, cadmium, and zinc.

    The greatest use of thallium is in specialized electronic research equipment. It is also used for production of optical lenses, jewelry, semiconductors, dyes, and pigments. The most common source of thallium poisoning is ingestion of rat poisons and insecticides.

    Purpose of Regulating Thallium: To improve public health protection.

    Public Health Benefit: To prevent hair loss, changes in blood, and kidney/liver/intestinal problems.

    MCL/MCLG: 0.002 mg/L/0.0005 mg/L

    Monitoring Requirements: Once a year for surface water; once every 3 years for groundwater. To minimize monitoring costs, use historical data, waivers, susceptibility waivers, or make composite samples.

    Organic Standards

    Organic chemicals are either natural or synthetic chemical compounds that contain carbon. Synthetic organic chemicals (SOCs) are manmade compounds and are used throughout the world as pesticides, paints, dyes, solvents, plastics, and food additives. Volatile organic chemicals (VOCs) are a subcategory of organic chemicals. These chemicals are termed volatile because they evaporate easily.

    The most commonly found VOCs are THMs, trichloroethylene (TCE), tetrachloroethylene, and 1,1-dichloroethylene. THMs were the first regulated VOCs when EPA finalized regulations in 1979. The most common sources of organic contamination of drinking water are pesticides and herbicides, industrial solvents, and DBPs (THMs and haloacetic acids).

    Millions of pounds of pesticides are used on croplands, forests, lawns, and gardens in the United States each year. They drain off into surface waters or seep into underground water supplies. Spills, poor storage, improper application, and haphazard disposal of organic chemicals have resulted in widespread groundwater contamination. A critical problem occurs once groundwater is contaminated, it may remain that way for a long time. Many organic chemicals pose health problems if they get into drinking water and the water is not properly treated.

    In 2011, EPA decided to address up to 16 volatile organic compounds (VOCs) as a group that may cause cancer. The agency determined that they represent a near-term opportunity and it is likely that the public health goal for all VOCs would likely be set at zero because they may cause cancer. A preliminary evaluation of occurrence indicates that some of these VOCs may co-occur. This group will include trichloroethylene (TCE) and tetrachloroethylene (PCE).

    EPA determined in March 2010 that the drinking water standards for TCE and PCE need to be revised. Addressing these VOCs as a group will help reduce exposure to these contaminants.

    Trichloroethylene (TCE)

    In the Code of Federal Regulations Reference: 40 CFR 141.50, although the use of TCE is declining because of stringent regulations, it was, for many years, a common ingredient in household products (spot removers, rug cleaners, and air fresheners), dry cleaning agents, industrial metal cleaners and polishes, refrigerants, and even anesthetics. Its wide range of use is perhaps why TCE is the organic contaminant most frequently encountered in groundwater.

    Purpose of Regulating Trichloroethylene: To improve public health protection.

    Public Health Benefit: To prevent cancer risks; liver problems.

    MCL/MCLG: 0.005 mg/L/zero

    Monitoring Requirements: Four consecutive quarterly samples during first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems. These requirements apply to community and non-community water systems.

    1,1-Dichloroethylene

    In the Code of Federal Regulations Reference: 40 CFR 141.50, this solvent is used in manufacturing plastics and, more recently, in the production of 1,1,1-trichloroethane.

    Purpose of Regulating 1,1-Dichloroethylene: To improve public health protection.

    Public Health Benefit: To prevent impacts to the liver, kidneys, heart, and central nervous system.

    MCL/MCLG: 0.007 mg/L/0.007 mg/L

    Monitoring Requirements/Comments: For VOCs: Four consecutive quarterly samples during first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems.

    With the completion of source water assessments, primacy agencies are allowed to develop alternative monitoring requirements. Applies to community water systems and non-transient

    Non-community water systems.

    Vinyl Chloride

    In the Code of Federal Regulations Reference: 40 CFR 141.50, billions of pounds of this solvent are used annually in the United States to produce polyvinyl chloride (PVC), the most widely used ingredient for manufacturing plastics throughout the world. Also evidence exists that vinyl chloride may be a biodegradation end-product of TCE and PCE under certain environmental conditions.

    Purpose of Regulating Vinyl Chloride: To improve public health protection.

    Public Health Benefit: To prevent cancer in humans.

    MCL/MCLG: 0.002 mg/L/zero

    Monitoring Requirements/Comments: For VOCs: Four consecutive quarterly samples during first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems.

    With the completion of source water assessments, primacy agencies are allowed to develop alternative monitoring requirements. Applies to community water systems and non-transient non-community water systems.

    Carbon Tetrachloride

    In the Code of Federal Regulations Reference: 40 CFR 141.50, carbon tetrachloride was once a popular household solvent, a frequently used dry cleaning agent, and a charging agent for fire extinguishers. Since 1970, however, carbon tetrachloride has been banned from all use in consumer goods in the United States.

    In 1978, carbon tetrachloride was banned as an aerosol propellant. Currently, its principal use is in the manufacture of fluorocarbons, which are used as refrigerants.

    Purpose of Regulating Carbon Tetrachloride: To improve public health protection.

    Public Health Benefit: To prevent liver problems and cancer.

    MCL/MCLG: 0.005 mg/L/zero

    Monitoring Requirements: Four consecutive quarterly samples during first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems. These requirements apply to community and non-community water systems.

    Benzene

    In the Code of Federal Regulations Reference: 40 CFR 141.50, benzene is used primarily in the synthesis of styrene (for plastics), phenol (for resins), and cyclohexane (for nylon). Other uses include the production of detergents, drugs, dyes, and insecticides. Benzene is still being used as a solvent and as a component of gasoline. It is also discharged from factories and leaches from gas storage tanks and landfills.

    Purpose of Regulating Benzene: To improve public health protection.

    Public Health Benefit: To prevent anemia, a decrease in blood platelets, and cancer.

    MCL/MCLG: 0.005 mg/L/zero

    Monitoring Requirements: Four consecutive quarterly samples during first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems. These requirements apply to community and non-community water systems.

    Para-Dichlorobenzene (p-Dichlorobenzene)

    In the Code of Federal Regulations Reference: 40 CFR 141.50, the principal uses of p-dichlorobenzene are in moth control (moth balls and powders) and as lavatory deodorants. It is also used as an insecticide and fungicide on crops; in the manufacture of other organic chemicals; and in plastics, dyes, and pharmaceuticals.

    The major source of p-dichlorobenzene in drinking water is discharge from industrial chemical factories.

    Purpose of Regulating Para-Dichlorobenzene (p-Dichlorobenzene): To improve public health protection.

    Public Health Benefit: To prevent kidney/liver/spleen/circulatory system problems.

    MCL/MCLG: 0.075 mg/L/0.075 mg/L

    Monitoring Requirements: Four consecutive quarterly samples during the first compliance period. Compliance is based on annual average of quarterly samples. If no detections are found during the initial round, two quarterly samples are required each year for systems serving greater than 3,300; one sample is required every 3 years for smaller systems. These requirements apply to community and non-community water systems.

    Disinfection By-Products

    Disinfection of drinking water by the addition of chlorine has long been considered a highly effective yet relatively low-cost method of preventing widespread outbreaks of waterborne diseases. In addition to reacting with disease-causing organisms in water, however, chlorine also reacts with many other types of organic materials.

    Growing scientific evidence suggests that the byproducts of these chemical reactions can produce adverse health effects in humans. The highest priority health risk concern in the regulation of drinking water is the potential risk-risk tradeoff between the control of microbiological contamination (bacteria, viruses, and protozoa) on one side and DBPs on the other. This risk-risk tradeoff arises because, typically, the least expensive way for a public water system to increase microbial control is to increase disinfection (which generally increases byproduct formation) and the easiest way to reduce byproducts is to decrease disinfection (which generally increases microbial risk).

    Microbiological contamination often causes flu-like symptoms; however, it can also cause serious diseases such as hepatitis, giardiasis, cryptosporidiosis, and Legionnaire’s Disease. DBPs may pose the risk of cancer and developmental effects.

    THMs are an example of a compound formed by the reaction of chlorine with organic matter in water. THMs are suspected of being carcinogenic and have been regulated by EPA in the 1996

    SDWA amendments. The MCL for TTHMs is 0.080 milligram per liter or 80 micrograms per liter.

    In May 1996, EPA published the Information Collection Rule (ICR). This rule required large public water systems to undertake extensive monitoring of microbial contaminants and DBPs in their water systems. Also, some water systems conducted studies on the use of granular activated carbon and membrane processes. The data reported under the ICR were used by EPA to learn more about the occurrence of microbial contamination and DBPs, the health risks posed, appropriate analytical methods, and effective forms of treatment. The ICR data form the scientific basis for EPA’s development of the Enhanced Surface Water Treatment Rule and the Disinfectants and Disinfection Byproducts Rule.

    EPA issued the Stage 1 DBPR on December 16, 1998 (Federal Register 63, No. 241). This rule set new MCLGs and MCLs for TTHMs, HAA5, bromate, and chlorite. Maximum residual disinfectant level goals (MRDLGs) and maximum residual disinfectant levels (MRDLs) have also been set for chlorine, chloramine, and chlorine dioxide.

    The Stage 1 DBPR attempts to further reduce potential formation of harmful DBPs by requiring the removal of THM precursors. A treatment technique of enhanced coagulation, enhanced softening, or use of granular activated carbon (GAC) applies to conventional filtration systems. In most cases, systems must reduce total organic carbon (TOC) levels based on specific source water quality factors.

    For large systems (serving more than 10,000 persons) that use surface water or groundwater under the direct influence of surface water, the compliance date for the Stage 1 DBPR was January 1, 2002. Small systems (serving fewer than 10,000) that use surface water or groundwater under the direct influence of surface water and all groundwater systems must have complied by January 1, 2004.

    The Stage 1 DBPR has very specific laboratory and monitoring requirements. The routine monitoring requirements include the following regulated contaminants/disinfectants:

    • TTHM/HAA5
    • Bromate
    • Chlorite
    • Chlorine/chloramines
    • Chlorine dioxide
    • DBP precursors (TOC/alkalinity/specific UV absorbance)

    Also, the Stage 1 DBPR specifies the monitoring coverage in terms of surface water, groundwater, and groundwater under direct influence (GWUDI), population served, and the type of filtration system and disinfection system. Monitoring frequency depends on the type of source water, population served, and type of treatment and disinfection system. The routine monitoring requirements are based on the regulated contaminants/disinfectants and include the MCL, MRDL, analytical method, preservation/quenching agent, holding time for sample/extract, and sample container size and type.

    On December 15, 2005, EPA promulgated the Stage 2 DBPR. This rule reduces potential cancer and reproductive and developmental health risks from DBPs in drinking water, which form when disinfectants are used to control microbial pathogens. This final rule strengthens public health protection for consumers by tightening compliance monitoring requirements for two groups of DBPs: TTHMs and HAA5.

    The rule targets systems with the greatest risk and builds incrementally on existing rules. This regulation reduces DBP exposure and related potential health risks and provides more equitable public health protection. The Stage 2 DBPR was promulgated simultaneously with the Long Term 2 Enhanced Surface Water Treatment Rule to address concerns about risk tradeoffs between pathogens and DBPs.

    Under the Stage 2 DBPR, systems will conduct an evaluation of their distribution systems, known as an Initial Distribution System Evaluation (IDSE), to identify the locations with high DBP concentrations. These locations are used by the systems as the sampling sites for Stage 2 DBPR compliance monitoring.

    Compliance with the maximum contaminant levels for two groups of DBPs (TTHMs and HAA5) is calculated for each monitoring location in the distribution system. This approach,

    referred to as the locational running annual average (LRAA), differs from previous requirements, which determine compliance by calculating the running annual average of samples from all monitoring locations across the system.

    The Stage 2 DBPR also requires each system to determine if they have exceeded an operational evaluation level, which is identified using their compliance monitoring results. The operational evaluation level provides an early warning of possible future MCL violations, which allows the system to take proactive steps to remain in compliance. A system that exceeds an operational evaluation level is required to review their operational practices and submit a report to their state that identifies actions that may be taken to mitigate future high DBP levels; particularly, those levels that may jeopardize their compliance with the DBP MCLs.

    Radionucleotide Standards

    EPA promulgated the Radionuclides Rule on December 7, 2000. The purpose of the Radionuclides Rule is to reduce the exposure to radionuclides in drinking water, which reduces the risk of cancer. This rule also improves public health protection by reducing exposure to all radionuclides. The rule applies to all community water systems.

    The public health benefits from the rule include reduced exposure to uranium, which can cause toxic kidney effects and cancer.

    In the Code of Federal Regulations Reference: 40 CFR 141.24, radioactivity is the only contaminant that has been shown to cause cancer for which standards have been set. Three radioactive elements, radon, radium, and uranium, occur naturally in the ground and dissolve into groundwater supplies. However, the possible exposure to radiation in drinking water is only a fraction of the exposure from all natural sources. The main source of radioactive material in surface water is fallout from nuclear testing. Other sources could be nuclear power plants, nuclear fuel processing plants, and uranium mines. Those sources are monitored constantly and no great risk of contamination exists, barring accidents.

    Alpha and radium radioactivity occur naturally in groundwater in parts of the West, Midwest, and Northeast. Standards for those types of radioactivity and for manmade, or beta radiation, have been set at levels of safety comparable to other contaminants. The MCLs for radiological contaminants are divided into two categories: natural radioactivity that results from well water passing through deposits of naturally occurring radioactive materials and manmade radioactivity such as might result from industrial wastes, hospitals, or research laboratories.

    A pCi/L, picoCurie per Liter, is a measure of radioactivity. One picoCurie of radioactivity is equivalent to 0.037 nuclear disintegrations per second. For surface water systems serving more than 100,000 persons and systems determined by the state to be vulnerable. Monitoring for natural radioactivity contamination is required every four years for surface water and groundwater community systems. Routine monitoring procedures to follow are:

    • Test for gross alpha activity; if gross alpha exceeds 5 pCi/L, then
    • Test for radium 226; if radium 226 exceeds 3 pCi/L, then
    • Test for radium 228.

    The MCL for gross beta particle activity is 4 mrem/yr for water systems using surface water and serving more than 100,000 people, and for any other community system determined by the state to be vulnerable to this type of contamination. After the initial monitoring period, beta radiation must be monitored every 4 years unless the MCL is exceeded or the state determines that more frequent monitoring is appropriate.

    Regulation of radon continues to be a source of considerable debate. EPA proposed a maximum contaminant level in 1991 and then withdrew the proposed MCL in 1997 in response to the 1996 SDWA amendments. EPA published a proposed regulation for radon in 1999, but the final MCL has not been published.

    The final Radionuclides Rule was published in 2000. The rule retains the current standards for radium 226 and 228, gross alpha activity, and gross beta particle activity, but establishes a new MCL 30 µg/L for uranium. The EPA has indicated that it will continue to review the standard for beta particle activity and may revise the MCL in the future. EPA must base its new rules on a scientific risk assessment and an analysis of the amount of health risk reduction that will be achieved and the cost of implementing the new rules.

    Microbial Standards

    Microbial contamination of drinking water can pose a potential public health risk in terms of acute outbreaks of disease. Bacteria, viruses, and other organisms have long been recognized as serious contaminants of drinking water. Organisms such as Giardia, Cryptosporidium, and E. coli (a type of coliform bacteria) cause almost immediate gastrointestinal illness when people consume them in water. Waterborne diseases such as typhoid, cholera, infectious hepatitis, and dysentery have been traced to improperly disinfected drinking water.

    In most communities, drinking water is treated to remove contaminants before being piped to consumers, and bacterial contamination of municipal water supplies has been largely eliminated by adding chlorine or applying other forms of disinfection to drinking water to prevent waterborne diseases. By treating drinking water and wastewater, diseases such as typhoid and cholera have been virtually eliminated.

    Many types of coliform bacteria from human and animal wastes may be found in drinking water if the water is not properly treated. Often, the bacteria do not cause diseases transmitted by water, although certain coliforms have been identified as the cause of traveler’s diarrhea. In general, however, the presence of coliform bacteria indicates that other harmful organisms may be present in the water.

    Throughout the early 1990s, chemical contaminants in drinking water were the focus of EPA’s regulatory efforts. With passage of the 1996 SDWA amendments, Congress directed EPA to focus on microbial contaminants and to promulgate a series of new regulations to improve treatment effectiveness. Significant new regulations of the microbial contaminant Cryptosporidium were promulgated in December 1998. The new regulations consist of mandatory treatment techniques similar to the current regulations for Giardia and coliform bacteria. Filtration and disinfection requirements for surface water systems are currently in place and the final Ground Water Rule was signed in 2006. These regulations significantly affect the water treatment processes of most water suppliers.

    Total Coliform Rule

    In the Code of Federal Regulations Reference: 40 CFR 141 Subpart C, coliforms are bacteria that are always present in the digestive tracts of animals, including humans, and are found in their wastes. They are also found in plant and soil material. The most basic test for bacterial contamination of a water supply is the test for total coliform bacteria. Total coliform counts give a general indication of the sanitary condition of a water supply.

    Coliforms include the following:

    • Total coliforms—include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste.
    • Fecal coliforms—are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals. Because the origins of fecal coliforms are more specific than the origins of the more general total coliform group of bacteria, fecal coliforms are considered a more accurate indication of animal or human waste than the total coliforms.

    Escherichia coli (E. coli) is the major species in the fecal coliform group. Of the five general groups of bacteria that comprise the total coliforms, only E. coli is generally not found growing and reproducing in the environment. Consequently, E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens.

    2012 Revised Total Coliform Rule (RTCR)

    EPA has revised the Total Coliform Rule so that public water systems in the US take steps to ensure the integrity of the drinking water distribution system and monitoring for the presence of microbial contamination. Public water systems and the state and local agencies that oversee them must comply with the RTCR beginning April 1, 2016. The final RTCR requires the following:

    1. Public water systems are to notify the public if a test exceeds the MCL for E. coli in drinking water
    2. Public water systems that are at risk and therefore vulnerable to microbial contamination are required to identify and fix the problems, including the potential sources and the pathways of contamination
    3. Criteria will be used for public water systems that are well operated to qualify for and stay on reduced monitoring, which could reduce water system burden
    4. Provide incentives for better system operation, in particular small systems
    5. Require additional monitoring requirements for seasonal systems such as campgrounds and state and national parks

    The RTCR establishes an MCLG and an MCL for E. coli and eliminates the MCLG and MCL for total coliforms, replacing them with treatment techniques for coliforms that require assessment and corrective action. EPA has established an MCLG of zero for E. coli, which is a more specific indicator of fecal contamination and those pathogens that are potentially more harmful than total coliform. EPA has removed the 1989 MCLG and MCL for total coliforms, although the acute total coliform MCL violation under the 1989 TCR has been maintained as the MCL for E. coli under the RTCR.

    Under the new treatment technique, total coliforms serve as the indicator of a potential pathway of contamination into the system’s distribution system. Public water supplies that exceed a specified frequency of total coliform occurrence must conduct an assessment to determine if any sanitary deficiencies exist; if found, they must be corrected. A public water system that experiences an E. coli MCL violation must conduct an assessment and correct any sanitary defects that are identified.

    Monthly notification requirements based only on the presence of total coliforms will no longer be required. Instead, the RTCR will require public notification when an E. coli MCL violation occurs, indicating a potential health threat or when a water system fails to assess and take corrective action.

    Sanitary Survey

    In the Code of Federal Regulations Reference: 40 CFR 141.2, sanitary surveys are conducted to identify possible health risks that may not be discovered by routine coliform sampling. The Total Coliform Rule requires community water systems serving fewer than 4,100 persons to complete an initial sanitary survey by June 1994 and to conduct subsequent surveys every 5 years.

    Non-community water systems are required to complete an initial sanitary survey by June 1999 and subsequent surveys every 5 years with the exception of those systems with protected and disinfected groundwater sources, which are allowed 10 years for subsequent surveys.

    A sanitary survey requires detailed planning, a thorough system survey, and reporting of the results. The planning portion involves a review of water quality records for compliance with applicable microbial, inorganic chemical, organic chemical, and radiological contaminant MCLs as well as the records of compliance with the monitoring requirements for those contaminants.

    The actual field survey is a detailed evaluation and inspection of the source of the water supply and all conveyances, storage, treatment, and distribution facilities to ensure protection from all pollution sources.

    The final report includes the date(s) of the survey, who was present during the survey, the survey findings, the recommended improvements to correct identified problems, and the target dates of completion for any improvements.

    Sampling Plan

    The Total Coliform Rule requires each water supply system to develop and follow a written sampling plan. Each plan must specifically identify sampling points throughout the distribution system. Sampling plans must be approved by the state regulatory agency and it is necessary to check with the state agency to determine the details of their review process and what documents need to be submitted.

    Laboratory Procedures

    In the Code of Federal Regulations Reference: 40 CFR 141.21 and 40 CFR 141 Subpart C, with regard to coliform testing methodology, EPA maintains a current list of analytical methods that are approved for monitoring drinking water supplies that is published and updated in 40 CFR 141. Examples of acceptable analytical methods for determining total coliforms include the following:

    • Multiple-tube fermentation technique (MTF)
    • Membrane filter technique (MF)
    • Presence-absence coliform test (P-A)
    • Colilert™ system (ONPG-MUG test)
    • Colisure test

    Regardless of the method used, the standard sample volume for total coliform testing is now 100 mL. This volume is an increase over the past testing method using 50 mL for the MTF technique.

    The multiple-tube fermentation method of testing for coliforms determines the presence or absence of coliforms by the multiple-tube dilution method. This test is a process whereby equal portions of a sample (100 mL) are added to 10 tubes containing a culture medium and an inverted vial. If gas accumulates in the inverted vial, it indicates presumptive evidence of coliform organisms and the sample is considered coliform-positive. If no gas forms in any of the vials, the sample is coliform-negative.

    The membrane filter method provides for filtering a 100 mL water sample through a thin, porous, cellulose membrane filter under a partial vacuum. The filter is placed in a sterile container and incubated in contact with a special liquid called a culture medium, which the bacteria use as a food source. Colonies of bacteria then grow on the media. The coliform colonies are visually identified, counted, and recorded as the number of coliform colonies per 100 mL of sample.

    Membrane-filter test
    Figure \(\PageIndex{1}\): Membrane filter test for coliforms – Image by the EPA is in the public domain

    The presence-absence (P-A) test for the coliform group is a simple modification of the multiple-tube procedure. Even though this simplified test uses only one large test portion (100 mL) in a single culture bottle, the results still indicate the presence or absence of coliform bacteria and thus meet the testing requirements.

    The Colilert™ system is a privately developed version of the ONPG-MUG test procedure that meets the EPA’s laboratory methods requirements. The ONPG-MUG test indicates the presence or absence of coliform bacteria within 24 hours. Although the Colilert™ method can yield presence-absence results within 24 hours and is easier to perform than the Membrane Filtration (MF) method, operators should be aware of the limitations of these tests in evaluating samples for regulatory purposes. The results for the Colilert™ and MF tests are not always comparable, which may be due to the following:

    • Interferences in the sample that may suppress or mask bacterial growth
    • Greater sensitivity of the Colilert™ media
    • Added stress to organisms related to filtering
    • The fact that different media may obtain better growth for some bacteria

    These test methods are approved by the EPA for reporting under the Safe Drinking Water Program. When these tests produce conflicting results, however, the safest course of action is to increase monitoring and treatment efforts until the results for each test is negative.

    The Colisure test is a presence-absence test for coliform bacteria. A sample of water is added to a dehydrated medium and, after 24 to 48 hours, the medium is examined for the presence of coliforms.

    Table 1.9.2: Total Coliform Indicator Color Chart

    Positive Test

    Negative Test

    • Many gas bubbles present
    • Gel rises to surface
    • Liquid below gel is cloudy
    • Indicator turns yellow
    • Liquid above gel is clear
    • Indicator remains red or turns yellow with no gas bubbles
    • Gel remains at bottom of tube

    Water supply systems may contain various other types of bacteria besides coliforms. These organisms are nonpathogenic bacteria and are sometimes referred to as heterotrophic bacteria. During the analyses of water samples for coliforms, heterotrophic bacteria sometimes interfere with the test causing one of the following reactions:

    • MTF technique: a turbid culture with no gas production
    • P-A test: a turbid culture in the absence of an acid reaction
    • MF technique: confluent growth or a coliform colony number too numerous to count

    The sample being tested can be considered invalid if any of these situations occurs and total coliforms are not detected. A replacement sample must be taken from the same location within 24 hours of receiving the laboratory results. If the replacement sample also shows heterotrophic interference but tests positive for total coliforms, the sample is considered valid.

    Monitoring Frequency

    The routine monitoring frequency for community water systems is based on the population served. Routine monitoring frequencies for non-community systems are based on the source of supply and, in some cases, the population served. Whenever a routine sample tests positive for total coliform, two provisions of the Total Coliform Rule take effect: repeat samples (formerly referred to as check samples) must be taken and the original coliform-positive sample must be tested for the presence of fecal coliforms or E. coli to determine whether an actual or potential violation of the coliform MCL exists.

    The reason repeat samples are required is to investigate whether the original coliform-positive sample was caused by a contamination problem that exists throughout the distribution system or if it is a localized problem that exists only at that one sampling point. With this information, appropriate corrective action can be taken to eliminate the problem as quickly as possible.

    The Total Coliform Rule specifies how many repeat samples must be taken, when, and from what locations. It also directs the water utility to collect a specific number of samples the following month, based on the number of routine samples ordinarily collected.

    Non-community systems serving more than 1,000 people have the same requirements as community water systems. Non-community systems serving fewer than 1,000 people are required to collect one routine sample per quarter. When the routine sample tests positive, four repeat samples are required in the same quarter and five samples are required the following quarter.

    Whenever a routine or repeat sample tests positive for total coliform, the water agency must collect a set of three or four repeat samples within 24 hours of receiving the laboratory results. At least one of the repeat samples must be taken from the same tap as the original coliform-positive sample; the remaining repeat samples in the set must be collected at nearby taps (within five service connections of the original sampling point), upstream and downstream of the original.

    Repeat samples must be taken until no coliforms are detected or until the MCL is exceeded and the state is notified.

    Determining Compliance

    The MCLG for total coliforms (including fecal coliforms and E. coli) is zero. The MCL, based on the presence-absence concept, is as follows:

    • For water systems analyzing at least 40 samples per month, no more than 5.0 percent of the samples (including routine and repeat samples) may be positive for total coliforms
    • For water systems analyzing fewer than 40 samples per month, no more than one sample per month may be positive for total coliforms

    The Revised Total Coliform Rule makes another significant change in the way compliance is calculated. All valid coliform-positive samples, routine and repeat samples, must be counted when calculating compliance with the monthly MCL. Under previous regulations, check or repeat samples were not included in the monthly MCL calculation. On a case-by-case basis, the state may declare a sample invalid for one of several reasons, including interference by heterotrophic bacteria during laboratory analysis, as previously discussed.

    Total-coliform-positive samples may be invalidated by the state under any of the following conditions:

    • The analytical laboratory acknowledges that improper sample analysis caused the positive result
    • The state determines that the contamination is a local plumbing problem
    • The state has substantial grounds to believe that the positive result was unrelated to the quality of drinking water in the distribution system

    Reporting and Notification Requirements

    Reporting frequencies for coliform test results increase in step with the urgency of the problem. A water agency must report the results of monthly coliform testing to the state regulatory agency within the first 10 days of the following month.

    Any time a water agency fails to collect a sample as required, the state must be notified within 10 days after the system learns of the violation. An invalid sample result is considered a failure to monitor and must be reported.

    If the MCL is exceeded, the state must be notified no later than the end of the next business day and the public within 14 days. This requirement could occur when the water agency exceeds its monthly coliform-positive limit or when test results show the presence of fecal coliforms or E. coli in any sample.

    The most critical situation exists when either of two situations occurs:

    • A routine sample tests positive for total coliforms and for fecal coliforms or E. coli, and any repeat sample tests positive for total coliforms.
    • A routine sample tests positive for total coliforms and negative for fecal coliforms or E. coli, and any repeat sample tests positive for fecal coliforms or E. coli.

    These situations are considered an acute risk to health. This occurrence is a Tier 1 violation, which requires that the state and the public be notified within 24 hours.

    Review Questions

    1. List the metals in the Safe Drinking Water Act that are considered to be primary contaminates.

    Contaminant

    MCLG
    (mg/L)

    MCL or TT
    (mg/L)

    Potential Health Effects from Ingestion of Water

    Sources of Contaminant in Drinking Water

    1. List the radiologic contaminates that drinking water plants are required to be tested for in the Safe Drinking Water Act.
    2. What is the action level for lead and copper in the Safe Drinking Water Act?
    3. What is the MCL for nitrate in drinking water?
    4. Which contaminate has a primary and secondary contaminate limit?
    5. List the disinfection by-products that are monitored and controlled in the Safe Drinking Water Act?
    6. Describe a Sanitary Survey.

    Chapter Quiz

    1. In the Code of Federal Regulations, 40CFR 141.2, a sanitary survey should be conducted every ___________.
      1. Year
      2. Two years
      3. Five years
      4. Six years
    2. EPA uses the ___________ to collect data for contaminants suspected to be present in drinking water, although they do not have health-based standards set under the Safe Drinking Water Act.
      1. Maximum Contaminate Level
      2. Maximum Contaminate Level Goal
      3. Unregulated Contaminate Monitoring
      4. Secondary Maximum Contaminate Level
    3. Which of the primary contaminates has an action level rather than an MCL?
      1. THMs and HAA5s
      2. Arsenic
      3. Mercury
      4. Lead and Copper
    4. In the Code of Federal Regulations Reference: 40 CFR 141.62, the amounts of cadmium that are found in natural waters in the United States is small. Waste discharges from the electroplating, photography, insecticide, and metallurgy industries can increase cadmium levels. The most common source of cadmium in drinking water is from galvanized pipes and fixtures. What is the MCL and MCLG for Cadmium?
      1. 5 ppb
      2. 50 ppb
      3. 5 ppm
      4. 50 ppm
    5. In the Code of Federal Regulations Reference: 40 CFR 141.62, chromium is found in cigarettes, some foods, and the air. It is also discharged from steel and pulp mills and the erosion of natural deposits. Some studies suggest that in very small amounts, chromium may be essential to human beings, but it has not been proven. Chromium VI or Hexavalent Chromium was the subject of the Erin Brockovich case and movie. What is the MCL and MCLG for Chromium?
      1. 1.0 ppb
      2. 10 ppb
      3. 1.0 ppm
      4. 0.1 ppm
    1. In order to prevent methemoglobinemia (blue baby syndrome)/diuresis, ___________ is monitored annually in groundwater and quarterly in surface water initially and then annually. The MCL is 10 mg/L.
      1. Nitrite
      2. Nitrate
      3. Sodium
      4. Chloride
    2. Microbiological contamination often causes flu-like symptoms; however, it can also cause serious diseases. Which of the following is not a waterborne disease?
      1. Hepatitis
      2. AIDS
      3. Giardiasis
      4. Legionnaire’s Disease
    3. The Revised Total Coliform Rule establishes an MCLG and an MCL for E. coli and eliminates the MCLG and MCL for total coliforms, replacing them with treatment techniques for coliforms that require assessment and corrective action. EPA has established an MCLG of ___________ for E. coli, which is a more specific indicator of fecal contamination than those pathogens that are potentially more harmful than total coliform.
      1. Zero
      2. One
      3. Three
      4. Depends on the number of samples that are taken each month by the water purveyor
    4. In the Code of Federal Regulations Reference: 40 CFR 141.24, ___________ is the only contaminant that has been shown to cause cancer for which standards have been set.
      1. Arsenic
      2. Chromium
      3. Radioactivity
      4. THMs
    5. Which of the following contaminants can potentially cause mental deficiencies primarily in children, if found in drinking water above the maximum level allowed by Safe Drinking Water Act?
      1. Copper
      2. Arsenic
      3. Mercury
      4. Lead

    1.9: Primary Standards is shared under a not declared license and was authored, remixed, and/or curated by John Rowe.

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