Archive for April, 2012
Cooling Towers
Tweet Cooling Tower – What is it? Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use water or air to cool the working fluid to near the air temperature. Cooling towers are used in chemical and petrochemical plants, power stations, oil refineries and HVAC systems for cooling down buildings. [...]
Cooling Tower – What is it?
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use water or air to cool the working fluid to near the air temperature.
Cooling towers are used in chemical and petrochemical plants, power stations, oil refineries and HVAC systems for cooling down buildings. The size varies from small rooftop units to gigantic industrial structures.
Cooling towers are ideal as humidification operations and they are classified into two categories – natural draft and mechanical draft.
HVAC
An HVAC (heating, ventilating, and air conditioning) cooling tower is used to get rid of heat from a chiller. Water-cooled chillers are usually more energy-efficient than air-cooled chillers because they reject heat at lower temperatures. Air-cooled chillers must reject heat at the higher “dry-bulb” temperature, and thus are less efficient on average. Large office buildings, hospitals, and schools typically use one or more cooling towers as part of their air conditioning systems. Industrial cooling towers are usually much larger than HVAC towers.
HVAC use of a cooling tower pairs the cooling tower with a water-cooled chiller or water-cooled condenser. A ton of air-conditioning is defined as the removal of 12,000 Btu/hour (3500 W). The equivalent ton on the cooling tower side actually rejects about 15,000 Btu/hour (4400 W) due to the additional waste heat-equivalent of the energy needed to drive the chiller’s compressor. This equivalent ton is defined as the heat rejection in cooling 3 US gallons/minute (1,500 pound/hour) of water 10 °F (6 °C), which amounts to 15,000 Btu/hour, assuming a chiller coefficient of performance (COP) of 4.0. This COP is equivalent to an energy efficiency ratio (EER) of 14.
Cooling towers are also used in HVAC systems that have multiple water source heat pumps that share a common piping water loop. In this type of system, the water circulating inside the water loop removes heat from the condenser of the heat pumps whenever the heat pumps are working in the cooling mode, then the externally-mounted cooling tower is used to remove heat from the water loop and reject it to the atmosphere. By contrast, when the heat pumps are in heating mode, the condensers draw heat out of the loop water and reject it into the space to be heated. When the water loop is being used primarily to supply heat to the building, the cooling tower is normally shut down (and may be drained or winterized to prevent freeze damage), and heat is supplied by other means, usually from separate boilers.
Industrial cooling towers
Industrial cooling towers remove heat from machinery or heated process material. Most large, industrial cooling towers remove the heat absorbed in the circulating cooling water systems used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants, food processing plants, semi-conductor plants, and other industrial facilities. The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71,600 cubic meters an hour (315,000 U.S. gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (i.e., 3,600 cubic meters an hour).
If that same plant had no cooling tower and used once-through cooling water, it would require about 100,000 cubic metres an hour and that amount of water would be continuously returned to the ocean, lake or river from which it was obtained and continuously re-supplied to the plant. Discharging large amounts of hot water may raise the temperature of a river or lake to an unacceptable level, since elevated water temperatures can kill fish and other aquatic life. A cooling tower dissipates heat into the atmosphere instead. Wind and air diffusion spreads the heat over a much larger area and thus dissipates heat more effectively in air than it could in a river or lake. Some coal-fired and nuclear power plants located in coastal areas do make use of once-through ocean water, but even there, the offshore discharge water outlet requires very careful design to avoid environmental problems.
Petroleum refineries also have very large cooling tower systems. A typical large refinery processing 40,000 metric tons of crude oil per day (300,000 barrels (48,000 m3) per day) circulates about 80,000 cubic meters of water per hour through its cooling tower system.
Water Sanitation in cooling towers
A low pH balance of the water in cooling tower is enough to suggest that the water is infected.
Cooling tower must be subjected to a totally automatic water treatment procedure to avoid:
Corrosion
Scaling
Fouling
Microbial Growth
Water should be filtered and treated with algaecides and biocides to prevent bacteria and algae growth and ensure smooth, uninterrupted circulation of water in the cooling tower system. The microbial growth leads to reduction of the heat transfer efficiency of the cooling system. Treating the water with chorine is an effective measure since it increases the pH balance of water and makes it more alkaline. All the water treatment chemicals must be compatible and with a desired pH range for achieving optimal effectiveness. Cooling tower water sanitation is made easier through use of metering pumps, chemicals, storage tanks, and water testing meters,
Check TDS or Total Dissolved Solids which includes biocides and several other inorganic and organic materials. The process of evaporation increases TDS. So, what is required is to bleed some amount of water and replace it with clean water so as to dilute TDS concentration. The water that is bled must be drained to the sewer to ensure that it is not circulated in the cooling tower once again.
Use a reliable meter to test your TDS concentration.
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Drinking Water Contaminants
Tweet Courtesy of the EPA National Primary Drinking Water Regulations National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Visit the list of regulated contaminants with links for more details. List [...]
Courtesy of the EPA
National Primary Drinking Water Regulations
National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Visit the list of regulated contaminants with links for more details.
- List of Contaminants & their Maximum Contaminant Level (MCLs)
- Regulation Development
- EPA’s Regulated Contaminant Timeline (PDF) (1 pp, 86 K ) (About PDF)
- National Primary Drinking Water Regulations- The complete regulations regarding these contaminants availible from the Code of Federal Regulations Website
Information on this section
- Alphabetical List (PDF) (6 pp, 924 K) (About PDF) EPA 816-F-09-0004, May 2009
List of Contaminants & their MCLs
An alphabetical listing with links to fact sheets on the primary drinking water regulations.
- Microorganisms
- Disinfectants
- Disinfection Byproducts
- Inorganic Chemicals
- Organic Chemicals
- Radionuclides
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Cryptosporidium | zero | TT 3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Giardia lamblia | zero | TT3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Heterotrophic plate count | n/a | TT3 |
HPC has no health effects; it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration of bacteria in drinking water, the better maintained the water system is. |
HPC measures a range of bacteria that are naturally present in the environment |
| Legionella | zero | TT3 |
Legionnaire’s Disease, a type of pneumonia |
Found naturally in water; multiplies in heating systems |
| Total Coliforms (including fecal coliform and E. Coli) | zero | 5.0%4 |
Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5 |
Coliforms are naturally present in the environment; as well as feces; fecal coliforms and E. coli only come from human and animal fecal waste. |
| Turbidity | n/a | TT3 |
Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. |
Soil runoff |
| Viruses (enteric) | zero | TT3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Bromate | zero | 0.010 |
Increased risk of cancer |
Byproduct of drinking water disinfection |
| Chlorite | 0.8 | 1.0 |
Anemia; infants & young children: nervous system effects |
Byproduct of drinking water disinfection |
| Haloacetic acids (HAA5) | n/a6 | 0.0607 |
Increased risk of cancer |
Byproduct of drinking water disinfection |
| Total Trihalomethanes (TTHMs) | –> n/a6 | –> 0.0807 |
Liver, kidney or central nervous system problems; increased risk of cancer |
Byproduct of drinking water disinfection |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Chloramines (as Cl2) | MRDLG=41 | MRDL=4.01 |
Eye/nose irritation; stomach discomfort, anemia |
Water additive used to control microbes |
| Chlorine (as Cl2) | MRDLG=41 | MRDL=4.01 |
Eye/nose irritation; stomach discomfort |
Water additive used to control microbes |
| Chlorine dioxide (as ClO2) | MRDLG=0.81 | MRDL=0.81 |
Anemia; infants & young children: nervous system effects |
Water additive used to control microbes |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Antimony | 0.006 | 0.006 |
Increase in blood cholesterol; decrease in blood sugar |
Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder |
| Arsenic | 07 | 0.010 as of 01/23/06 |
Skin damage or problems with circulatory systems, and may have increased risk of getting cancer |
Erosion of natural deposits; runoff from orchards, runoff from glass & electronicsproduction wastes |
| Asbestos (fiber >10 micrometers) | 7 million fibers per liter | 7 MFL |
Increased risk of developing benign intestinal polyps |
Decay of asbestos cement in water mains; erosion of natural deposits |
| Barium | 2 | 2 |
Increase in blood pressure |
Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits |
| Beryllium | 0.004 | 0.004 |
Intestinal lesions |
Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries |
| Cadmium | 0.005 | 0.005 |
Kidney damage |
Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints |
| Chromium (total) | 0.1 | 0.1 |
Allergic dermatitis |
Discharge from steel and pulp mills; erosion of natural deposits |
| Copper | 1.3 | TT7; Action Level=1.3 |
Short term exposure: Gastrointestinal distress Long term exposure: Liver or kidney damage People with Wilson’s Disease should consult their personal doctor if the amount of copper in their water exceeds the action level |
Corrosion of household plumbing systems; erosion of natural deposits |
| Cyanide (as free cyanide) | 0.2 | 0.2 |
Nerve damage or thyroid problems |
Discharge from steel/metal factories; discharge from plastic and fertilizer factories |
| Fluoride | 4.0 | 4.0 |
Bone disease (pain and tenderness of the bones); Children may get mottled teeth |
Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories |
| Lead | zero | TT7; Action Level=0.015 |
Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities Adults: Kidney problems; high blood pressure |
Corrosion of household plumbing systems; erosion of natural deposits |
| Mercury (inorganic) | 0.002 | 0.002 |
Kidney damage |
Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands |
| Nitrate (measured as Nitrogen) | 10 | 10 |
Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. |
Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits |
| Nitrite (measured as Nitrogen) | 1 | 1 |
Infants below the age of six months who drink water containing nitrite in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. |
Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits |
| Selenium | 0.05 | 0.05 |
Hair or fingernail loss; numbness in fingers or toes; circulatory problems |
Discharge from petroleum refineries; erosion of natural deposits; discharge from mines |
| Thallium | 0.0005 | 0.002 |
Hair loss; changes in blood; kidney, intestine, or liver problems |
Leaching from ore-processing sites; discharge from electronics, glass, and drug factories |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Acrylamide | zero | TT8 |
Nervous system or blood problems; increased risk of cancer |
Added to water during sewage/wastewater treatment |
| Alachlor | zero | 0.002 |
Eye, liver, kidney or spleen problems; anemia; increased risk of cancer |
Runoff from herbicide used on row crops |
| Atrazine | 0.003 | 0.003 |
Cardiovascular system or reproductive problems |
Runoff from herbicide used on row crops |
| Benzene | zero | 0.005 |
Anemia; decrease in blood platelets; increased risk of cancer |
Discharge from factories; leaching from gas storage tanks and landfills |
| Benzo(a)pyrene (PAHs) | zero | 0.0002 |
Reproductive difficulties; increased risk of cancer |
Leaching from linings of water storage tanks and distribution lines |
| Carbofuran | 0.04 | 0.04 |
Problems with blood, nervous system, or reproductive system |
Leaching of soil fumigant used on rice and alfalfa |
| Carbon tetrachloride | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from chemical plants and other industrial activities |
| Chlordane | zero | 0.002 |
Liver or nervous system problems; increased risk of cancer |
Residue of banned termiticide |
| Chlorobenzene | 0.1 | 0.1 |
Liver or kidney problems |
Discharge from chemical and agricultural chemical factories |
| 2,4-D | 0.07 | 0.07 |
Kidney, liver, or adrenal gland problems |
Runoff from herbicide used on row crops |
| Dalapon | 0.2 | 0.2 |
Minor kidney changes |
Runoff from herbicide used on rights of way |
| 1,2-Dibromo-3-chloropropane (DBCP) | zero | 0.0002 |
Reproductive difficulties; increased risk of cancer |
Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards |
| o-Dichlorobenzene | 0.6 | 0.6 |
Liver, kidney, or circulatory system problems |
Discharge from industrial chemical factories |
| p-Dichlorobenzene | 0.075 | 0.075 |
Anemia; liver, kidney or spleen damage; changes in blood |
Discharge from industrial chemical factories |
| 1,2-Dichloroethane | zero | 0.005 |
Increased risk of cancer |
Discharge from industrial chemical factories |
| 1,1-Dichloroethylene | 0.007 | 0.007 |
Liver problems |
Discharge from industrial chemical factories |
| cis-1,2-Dichloroethylene | 0.07 | 0.07 |
Liver problems |
Discharge from industrial chemical factories |
| trans-1,2-Dichloroethylene | 0.1 | 0.1 |
Liver problems |
Discharge from industrial chemical factories |
| Dichloromethane | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from drug and chemical factories |
| 1,2-Dichloropropane | zero | 0.005 |
Increased risk of cancer |
Discharge from industrial chemical factories |
| Di(2-ethylhexyl) adipate | 0.4 | 0.4 |
Weight loss, liver problems, or possible reproductive difficulties. |
Discharge from chemical factories |
| Di(2-ethylhexyl) phthalate | zero | 0.006 |
Reproductive difficulties; liver problems; increased risk of cancer |
Discharge from rubber and chemical factories |
| Dinoseb | 0.007 | 0.007 |
Reproductive difficulties |
Runoff from herbicide used on soybeans and vegetables |
| Dioxin (2,3,7,8-TCDD) | zero | 0.00000003 |
Reproductive difficulties; increased risk of cancer |
Emissions from waste incineration and other combustion; discharge from chemical factories |
| Diquat | 0.02 | 0.02 |
Cataracts |
Runoff from herbicide use |
| Endothall | 0.1 | 0.1 |
Stomach and intestinal problems |
Runoff from herbicide use |
| Endrin | 0.002 | 0.002 |
Liver problems |
Residue of banned insecticide |
| Epichlorohydrin | zero | TT8 |
Increased cancer risk, and over a long period of time, stomach problems |
Discharge from industrial chemical factories; an impurity of some water treatment chemicals |
| Ethylbenzene | 0.7 | 0.7 |
Liver or kidneys problems |
Discharge from petroleum refineries |
| Ethylene dibromide | zero | 0.00005 |
Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancer |
Discharge from petroleum refineries |
| Glyphosate | 0.7 | 0.7 |
Kidney problems; reproductive difficulties |
Runoff from herbicide use |
| Heptachlor | zero | 0.0004 |
Liver damage; increased risk of cancer |
Residue of banned termiticide |
| Heptachlor epoxide | zero | 0.0002 |
Liver damage; increased risk of cancer |
Breakdown of heptachlor |
| Hexachlorobenzene | zero | 0.001 |
Liver or kidney problems; reproductive difficulties; increased risk of cancer |
Discharge from metal refineries and agricultural chemical factories |
| Hexachlorocyclopentadiene | 0.05 | 0.05 |
Kidney or stomach problems |
Discharge from chemical factories |
| Lindane | 0.0002 | 0.0002 |
Liver or kidney problems |
Runoff/leaching from insecticide used on cattle, lumber, gardens |
| Methoxychlor | 0.04 | 0.04 |
Reproductive difficulties |
Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock |
| Oxamyl (Vydate) | 0.2 | 0.2 |
Slight nervous system effects |
Runoff/leaching from insecticide used on apples, potatoes, and tomatoes |
| Polychlorinated biphenyls (PCBs) | zero | 0.0005 |
Skin changes; thymus gland problems; immune deficiencies; reproductive or nervous system difficulties; increased risk of cancer |
Runoff from landfills; discharge of waste chemicals |
| Pentachlorophenol | zero | 0.001 |
Liver or kidney problems; increased cancer risk |
Discharge from wood preserving factories |
| Picloram | 0.5 | 0.5 |
Liver problems |
Herbicide runoff |
| Simazine | 0.004 | 0.004 |
Problems with blood |
Herbicide runoff |
| Styrene | 0.1 | 0.1 |
Liver, kidney, or circulatory system problems |
Discharge from rubber and plastic factories; leaching from landfills |
| Tetrachloroethylene | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from factories and dry cleaners |
| Toluene | 1 | 1 |
Nervous system, kidney, or liver problems |
Discharge from petroleum factories |
| Toxaphene | zero | 0.003 |
Kidney, liver, or thyroid problems; increased risk of cancer |
Runoff/leaching from insecticide used on cotton and cattle |
| 2,4,5-TP (Silvex) | 0.05 | 0.05 |
Liver problems |
Residue of banned herbicide |
| 1,2,4-Trichlorobenzene | 0.07 | 0.07 |
Changes in adrenal glands |
Discharge from textile finishing factories |
| 1,1,1-Trichloroethane | 0.20 | 0.2 |
Liver, nervous system, or circulatory problems |
Discharge from metal degreasing sites and other factories |
| 1,1,2-Trichloroethane | 0.003 | 0.005 |
Liver, kidney, or immune system problems |
Discharge from industrial chemical factories |
| Trichloroethylene | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from metal degreasing sites and other factories |
| Vinyl chloride | zero | 0.002 |
Increased risk of cancer |
Leaching from PVC pipes; discharge from plastic factories |
| Xylenes (total) | 10 | 10 |
Nervous system damage |
Discharge from petroleum factories; discharge from chemical factories |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Alpha particles | none7 ———- zero | 15 picocuries per Liter (pCi/L) |
Increased risk of cancer |
Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation |
| Beta particles and photon emitters |
none7 ———- zero | 4 millirems per year |
Increased risk of cancer |
Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation |
| Radium 226 and Radium 228 (combined) | none7 ———- zero | 5 pCi/L |
Increased risk of cancer |
Erosion of natural deposits |
| Uranium | zero |
30 ug/L as of 12/08/03 |
Increased risk of cancer, kidney toxicity | Erosion of natural deposits |
Notes
1 Definitions: Maximum Contaminant Level Goal (MCLG) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals. Maximum Contaminant Level (MCL) – The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. Maximum Residual Disinfectant Level Goal (MRDLG) – The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants. (TT) Treatment Technique – A required process intended to reduce the level of a contaminant in drinking water. Maximum Residual Disinfectant Level (MRDL) – The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.
3 EPA’s surface water treatment rules require systems using surface water or ground water under the direct influence of surface water to (1) disinfect their water, and (2) filter their water or meet criteria for avoiding filtration so that the following contaminants are controlled at the following levels:
- Cryptosporidium: Unfiltered systems are required to include Cryptosporidium in their existing watershed control provisions.
- Giardia lamblia: 99.9% removal/inactivation
- Viruses: 99.99% removal/inactivation
- Legionella: No limit, but EPA believes that if Giardia and viruses are removed/inactivated, according to the treatment techniques in the Surface Water Treatment Rule, Legionella will also be controlled.
- Turbidity: For systems that use conventional or direct filtration, at no time can turbidity (cloudiness of water) go higher than 1 nephelolometric turbidity unit NTU), and samples for turbidity must be less than or equal to 0.3 NTU in at least 95 percent of the samples in any month. Systems that use filtration other than the conventional or direct filtration must follow state limits, which must include turbidity at no time exceeding 5 NTU.
- HPC: No more than 500 bacterial colonies per milliliter.
- Long Term 1 Enhanced Surface Water Treatment: Surface water systems or (GWUDI) systems serving fewer than 10,000 people must comply with the applicable Long Term 1 Enhanced Surface Water Treatment Rule provisions (e.g. turbidity standards, individual filter monitoring, Cryptosporidium removal requirements, updated watershed control requirements for unfiltered systems).
- Long Term 2 Enhanced Surface Water Treatment Rule This rule applies to all surface water systems or ground water systems under the direct influence of surface water. The rule targets additional Cryptosporidium treatment requirements for higher risk systems and includes provisions to reduce risks from uncovered finished water storage facilities and to ensure that the systems maintain microbial protection as they take steps to reduce the formation of disinfection byproducts.
- Filter Backwash Recycling; The Filter Backwash Recycling Rule requires systems that recycle to return specific recycle flows through all processes of the system’s existing conventional or direct filtration system or at an alternate location approved by the state.
4 No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.) Every sample that has total coliform must be analyzed for either fecal coliforms or E. coli if two consecutive TC-positive samples, and one is also positive for E.coli fecal coliforms, system has an acute MCL violation.
5 Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Disease-causing microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. These pathogens may pose a special health risk for infants, young children, and people with severely compromised immune systems.
6 Although there is no collective MCLG for this contaminant group, there are individual MCLGs for some of the individual contaminants:
- Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L): chloroform (0.07mg/L).
- Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.02 mg/L); monochloroacetic acid (0.07 mg/L). Bromoacetic acid and dibromoacetic acid are regulated with this group but have no MCLGs.
7 Lead and copper are regulated by a Treatment Technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L.
8 Each water system must certify, in writing, to the state (using third-party or manufacturer’s certification) that when acrylamide and epichlorohydrin are used to treat water, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows:
- Acrylamide = 0.05% dosed at 1 mg/L (or equivalent)
- Epichlorohydrin = 0.01% dosed at 20 mg/L (or equivalent)
National Secondary Drinking Water Regulations
National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
- National Secondary Drinking Water Regulations - The complete regulations regarding these contaminants available from the Code of Federal Regulations Web Site.
- For more information, read Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.
| Contaminant | Secondary Standard |
|---|---|
| Aluminum | 0.05 to 0.2 mg/L |
| Chloride | 250 mg/L |
| Color | 15 (color units) |
| Copper | 1.0 mg/L |
| Corrosivity | noncorrosive |
| Fluoride | 2.0 mg/L |
| Foaming Agents | 0.5 mg/L |
| Iron | 0.3 mg/L |
| Manganese | 0.05 mg/L |
| Odor | 3 threshold odor number |
| pH | 6.5-8.5 |
| Silver | 0.10 mg/L |
| Sulfate | 250 mg/L |
| Total Dissolved Solids | 500 mg/L |
| Zinc | 5 mg/L |
Unregulated Contaminants
This list of contaminants which, at the time of publication, are not subject to any proposed or promulgated national primary drinking water regulation (NPDWR), are known or anticipated to occur in public water systems, and may require regulations under SDWA. For more information check out the list, or vist the Drinking Water Contaminant Candidate List (CCL) web site.
- Drinking Water Contaminant Candidate List 2
- Drinking Water Contaminant Candidate List (CCL) Web Site
- Unregulated Contaminant Monitoring Program (UCM)
- Information on specific unregulated contaminants
- MTBE (methyl-t-butyl ether) in drinking water
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Drinking Water Contaminants
Tweet [[posterous-content:pid___0]] Courtesy of the EPA National Primary Drinking Water Regulations National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Visit the list of regulated contaminants with links for more details. [...]
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Courtesy of the EPA
National Primary Drinking Water Regulations
National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Visit the list of regulated contaminants with links for more details.
- List of Contaminants & their Maximum Contaminant Level (MCLs)
- Regulation Development
- EPA’s Regulated Contaminant Timeline (PDF) (1 pp, 86 K ) (About PDF)
- National Primary Drinking Water Regulations- The complete regulations regarding these contaminants availible from the Code of Federal Regulations Website
Information on this section
- Alphabetical List (PDF) (6 pp, 924 K) (About PDF) EPA 816-F-09-0004, May 2009
List of Contaminants & their MCLs
An alphabetical listing with links to fact sheets on the primary drinking water regulations.
- Microorganisms
- Disinfectants
- Disinfection Byproducts
- Inorganic Chemicals
- Organic Chemicals
- Radionuclides
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Cryptosporidium | zero | TT 3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Giardia lamblia | zero | TT3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Heterotrophic plate count | n/a | TT3 |
HPC has no health effects; it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration of bacteria in drinking water, the better maintained the water system is. |
HPC measures a range of bacteria that are naturally present in the environment |
| Legionella | zero | TT3 |
Legionnaire’s Disease, a type of pneumonia |
Found naturally in water; multiplies in heating systems |
| Total Coliforms (including fecal coliform and E. Coli) | zero | 5.0%4 |
Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present5 |
Coliforms are naturally present in the environment; as well as feces; fecal coliforms and E. coli only come from human and animal fecal waste. |
| Turbidity | n/a | TT3 |
Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. |
Soil runoff |
| Viruses (enteric) | zero | TT3 |
Gastrointestinal illness (e.g., diarrhea, vomiting, cramps) |
Human and animal fecal waste |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Bromate | zero | 0.010 |
Increased risk of cancer |
Byproduct of drinking water disinfection |
| Chlorite | 0.8 | 1.0 |
Anemia; infants & young children: nervous system effects |
Byproduct of drinking water disinfection |
| Haloacetic acids (HAA5) | n/a6 | 0.0607 |
Increased risk of cancer |
Byproduct of drinking water disinfection |
| Total Trihalomethanes (TTHMs) | –> n/a6 | –> 0.0807 |
Liver, kidney or central nervous system problems; increased risk of cancer |
Byproduct of drinking water disinfection |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Chloramines (as Cl2) | MRDLG=41 | MRDL=4.01 |
Eye/nose irritation; stomach discomfort, anemia |
Water additive used to control microbes |
| Chlorine (as Cl2) | MRDLG=41 | MRDL=4.01 |
Eye/nose irritation; stomach discomfort |
Water additive used to control microbes |
| Chlorine dioxide (as ClO2) | MRDLG=0.81 | MRDL=0.81 |
Anemia; infants & young children: nervous system effects |
Water additive used to control microbes |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Antimony | 0.006 | 0.006 |
Increase in blood cholesterol; decrease in blood sugar |
Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder |
| Arsenic | 07 | 0.010 as of 01/23/06 |
Skin damage or problems with circulatory systems, and may have increased risk of getting cancer |
Erosion of natural deposits; runoff from orchards, runoff from glass & electronicsproduction wastes |
| Asbestos (fiber >10 micrometers) | 7 million fibers per liter | 7 MFL |
Increased risk of developing benign intestinal polyps |
Decay of asbestos cement in water mains; erosion of natural deposits |
| Barium | 2 | 2 |
Increase in blood pressure |
Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits |
| Beryllium | 0.004 | 0.004 |
Intestinal lesions |
Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industries |
| Cadmium | 0.005 | 0.005 |
Kidney damage |
Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries; runoff from waste batteries and paints |
| Chromium (total) | 0.1 | 0.1 |
Allergic dermatitis |
Discharge from steel and pulp mills; erosion of natural deposits |
| Copper | 1.3 | TT7; Action Level=1.3 |
Short term exposure: Gastrointestinal distress Long term exposure: Liver or kidney damage People with Wilson’s Disease should consult their personal doctor if the amount of copper in their water exceeds the action level |
Corrosion of household plumbing systems; erosion of natural deposits |
| Cyanide (as free cyanide) | 0.2 | 0.2 |
Nerve damage or thyroid problems |
Discharge from steel/metal factories; discharge from plastic and fertilizer factories |
| Fluoride | 4.0 | 4.0 |
Bone disease (pain and tenderness of the bones); Children may get mottled teeth |
Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories |
| Lead | zero | TT7; Action Level=0.015 |
Infants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities Adults: Kidney problems; high blood pressure |
Corrosion of household plumbing systems; erosion of natural deposits |
| Mercury (inorganic) | 0.002 | 0.002 |
Kidney damage |
Erosion of natural deposits; discharge from refineries and factories; runoff from landfills and croplands |
| Nitrate (measured as Nitrogen) | 10 | 10 |
Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. |
Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits |
| Nitrite (measured as Nitrogen) | 1 | 1 |
Infants below the age of six months who drink water containing nitrite in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. |
Runoff from fertilizer use; leaking from septic tanks, sewage; erosion of natural deposits |
| Selenium | 0.05 | 0.05 |
Hair or fingernail loss; numbness in fingers or toes; circulatory problems |
Discharge from petroleum refineries; erosion of natural deposits; discharge from mines |
| Thallium | 0.0005 | 0.002 |
Hair loss; changes in blood; kidney, intestine, or liver problems |
Leaching from ore-processing sites; discharge from electronics, glass, and drug factories |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Acrylamide | zero | TT8 |
Nervous system or blood problems; increased risk of cancer |
Added to water during sewage/wastewater treatment |
| Alachlor | zero | 0.002 |
Eye, liver, kidney or spleen problems; anemia; increased risk of cancer |
Runoff from herbicide used on row crops |
| Atrazine | 0.003 | 0.003 |
Cardiovascular system or reproductive problems |
Runoff from herbicide used on row crops |
| Benzene | zero | 0.005 |
Anemia; decrease in blood platelets; increased risk of cancer |
Discharge from factories; leaching from gas storage tanks and landfills |
| Benzo(a)pyrene (PAHs) | zero | 0.0002 |
Reproductive difficulties; increased risk of cancer |
Leaching from linings of water storage tanks and distribution lines |
| Carbofuran | 0.04 | 0.04 |
Problems with blood, nervous system, or reproductive system |
Leaching of soil fumigant used on rice and alfalfa |
| Carbon tetrachloride | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from chemical plants and other industrial activities |
| Chlordane | zero | 0.002 |
Liver or nervous system problems; increased risk of cancer |
Residue of banned termiticide |
| Chlorobenzene | 0.1 | 0.1 |
Liver or kidney problems |
Discharge from chemical and agricultural chemical factories |
| 2,4-D | 0.07 | 0.07 |
Kidney, liver, or adrenal gland problems |
Runoff from herbicide used on row crops |
| Dalapon | 0.2 | 0.2 |
Minor kidney changes |
Runoff from herbicide used on rights of way |
| 1,2-Dibromo-3-chloropropane (DBCP) | zero | 0.0002 |
Reproductive difficulties; increased risk of cancer |
Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards |
| o-Dichlorobenzene | 0.6 | 0.6 |
Liver, kidney, or circulatory system problems |
Discharge from industrial chemical factories |
| p-Dichlorobenzene | 0.075 | 0.075 |
Anemia; liver, kidney or spleen damage; changes in blood |
Discharge from industrial chemical factories |
| 1,2-Dichloroethane | zero | 0.005 |
Increased risk of cancer |
Discharge from industrial chemical factories |
| 1,1-Dichloroethylene | 0.007 | 0.007 |
Liver problems |
Discharge from industrial chemical factories |
| cis-1,2-Dichloroethylene | 0.07 | 0.07 |
Liver problems |
Discharge from industrial chemical factories |
| trans-1,2-Dichloroethylene | 0.1 | 0.1 |
Liver problems |
Discharge from industrial chemical factories |
| Dichloromethane | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from drug and chemical factories |
| 1,2-Dichloropropane | zero | 0.005 |
Increased risk of cancer |
Discharge from industrial chemical factories |
| Di(2-ethylhexyl) adipate | 0.4 | 0.4 |
Weight loss, liver problems, or possible reproductive difficulties. |
Discharge from chemical factories |
| Di(2-ethylhexyl) phthalate | zero | 0.006 |
Reproductive difficulties; liver problems; increased risk of cancer |
Discharge from rubber and chemical factories |
| Dinoseb | 0.007 | 0.007 |
Reproductive difficulties |
Runoff from herbicide used on soybeans and vegetables |
| Dioxin (2,3,7,8-TCDD) | zero | 0.00000003 |
Reproductive difficulties; increased risk of cancer |
Emissions from waste incineration and other combustion; discharge from chemical factories |
| Diquat | 0.02 | 0.02 |
Cataracts |
Runoff from herbicide use |
| Endothall | 0.1 | 0.1 |
Stomach and intestinal problems |
Runoff from herbicide use |
| Endrin | 0.002 | 0.002 |
Liver problems |
Residue of banned insecticide |
| Epichlorohydrin | zero | TT8 |
Increased cancer risk, and over a long period of time, stomach problems |
Discharge from industrial chemical factories; an impurity of some water treatment chemicals |
| Ethylbenzene | 0.7 | 0.7 |
Liver or kidneys problems |
Discharge from petroleum refineries |
| Ethylene dibromide | zero | 0.00005 |
Problems with liver, stomach, reproductive system, or kidneys; increased risk of cancer |
Discharge from petroleum refineries |
| Glyphosate | 0.7 | 0.7 |
Kidney problems; reproductive difficulties |
Runoff from herbicide use |
| Heptachlor | zero | 0.0004 |
Liver damage; increased risk of cancer |
Residue of banned termiticide |
| Heptachlor epoxide | zero | 0.0002 |
Liver damage; increased risk of cancer |
Breakdown of heptachlor |
| Hexachlorobenzene | zero | 0.001 |
Liver or kidney problems; reproductive difficulties; increased risk of cancer |
Discharge from metal refineries and agricultural chemical factories |
| Hexachlorocyclopentadiene | 0.05 | 0.05 |
Kidney or stomach problems |
Discharge from chemical factories |
| Lindane | 0.0002 | 0.0002 |
Liver or kidney problems |
Runoff/leaching from insecticide used on cattle, lumber, gardens |
| Methoxychlor | 0.04 | 0.04 |
Reproductive difficulties |
Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock |
| Oxamyl (Vydate) | 0.2 | 0.2 |
Slight nervous system effects |
Runoff/leaching from insecticide used on apples, potatoes, and tomatoes |
| Polychlorinated biphenyls (PCBs) | zero | 0.0005 |
Skin changes; thymus gland problems; immune deficiencies; reproductive or nervous system difficulties; increased risk of cancer |
Runoff from landfills; discharge of waste chemicals |
| Pentachlorophenol | zero | 0.001 |
Liver or kidney problems; increased cancer risk |
Discharge from wood preserving factories |
| Picloram | 0.5 | 0.5 |
Liver problems |
Herbicide runoff |
| Simazine | 0.004 | 0.004 |
Problems with blood |
Herbicide runoff |
| Styrene | 0.1 | 0.1 |
Liver, kidney, or circulatory system problems |
Discharge from rubber and plastic factories; leaching from landfills |
| Tetrachloroethylene | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from factories and dry cleaners |
| Toluene | 1 | 1 |
Nervous system, kidney, or liver problems |
Discharge from petroleum factories |
| Toxaphene | zero | 0.003 |
Kidney, liver, or thyroid problems; increased risk of cancer |
Runoff/leaching from insecticide used on cotton and cattle |
| 2,4,5-TP (Silvex) | 0.05 | 0.05 |
Liver problems |
Residue of banned herbicide |
| 1,2,4-Trichlorobenzene | 0.07 | 0.07 |
Changes in adrenal glands |
Discharge from textile finishing factories |
| 1,1,1-Trichloroethane | 0.20 | 0.2 |
Liver, nervous system, or circulatory problems |
Discharge from metal degreasing sites and other factories |
| 1,1,2-Trichloroethane | 0.003 | 0.005 |
Liver, kidney, or immune system problems |
Discharge from industrial chemical factories |
| Trichloroethylene | zero | 0.005 |
Liver problems; increased risk of cancer |
Discharge from metal degreasing sites and other factories |
| Vinyl chloride | zero | 0.002 |
Increased risk of cancer |
Leaching from PVC pipes; discharge from plastic factories |
| Xylenes (total) | 10 | 10 |
Nervous system damage |
Discharge from petroleum factories; discharge from chemical factories |
| Contaminant | MCLG1(mg/L)2 | MCL orTT1(mg/L)2 | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water |
|---|---|---|---|---|
| Alpha particles | none7 ———- zero | 15 picocuries per Liter (pCi/L) |
Increased risk of cancer |
Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation |
| Beta particles and photon emitters |
none7 ———- zero | 4 millirems per year |
Increased risk of cancer |
Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation |
| Radium 226 and Radium 228 (combined) | none7 ———- zero | 5 pCi/L |
Increased risk of cancer |
Erosion of natural deposits |
| Uranium | zero |
30 ug/L as of 12/08/03 |
Increased risk of cancer, kidney toxicity | Erosion of natural deposits |
Notes
1 Definitions: Maximum Contaminant Level Goal (MCLG) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals. Maximum Contaminant Level (MCL) – The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. Maximum Residual Disinfectant Level Goal (MRDLG) – The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants. (TT) Treatment Technique – A required process intended to reduce the level of a contaminant in drinking water. Maximum Residual Disinfectant Level (MRDL) – The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.
3 EPA’s surface water treatment rules require systems using surface water or ground water under the direct influence of surface water to (1) disinfect their water, and (2) filter their water or meet criteria for avoiding filtration so that the following contaminants are controlled at the following levels:
- Cryptosporidium: Unfiltered systems are required to include Cryptosporidium in their existing watershed control provisions.
- Giardia lamblia: 99.9% removal/inactivation
- Viruses: 99.99% removal/inactivation
- Legionella: No limit, but EPA believes that if Giardia and viruses are removed/inactivated, according to the treatment techniques in the Surface Water Treatment Rule, Legionella will also be controlled.
- Turbidity: For systems that use conventional or direct filtration, at no time can turbidity (cloudiness of water) go higher than 1 nephelolometric turbidity unit NTU), and samples for turbidity must be less than or equal to 0.3 NTU in at least 95 percent of the samples in any month. Systems that use filtration other than the conventional or direct filtration must follow state limits, which must include turbidity at no time exceeding 5 NTU.
- HPC: No more than 500 bacterial colonies per milliliter.
- Long Term 1 Enhanced Surface Water Treatment: Surface water systems or (GWUDI) systems serving fewer than 10,000 people must comply with the applicable Long Term 1 Enhanced Surface Water Treatment Rule provisions (e.g. turbidity standards, individual filter monitoring, Cryptosporidium removal requirements, updated watershed control requirements for unfiltered systems).
- Long Term 2 Enhanced Surface Water Treatment Rule This rule applies to all surface water systems or ground water systems under the direct influence of surface water. The rule targets additional Cryptosporidium treatment requirements for higher risk systems and includes provisions to reduce risks from uncovered finished water storage facilities and to ensure that the systems maintain microbial protection as they take steps to reduce the formation of disinfection byproducts.
- Filter Backwash Recycling; The Filter Backwash Recycling Rule requires systems that recycle to return specific recycle flows through all processes of the system’s existing conventional or direct filtration system or at an alternate location approved by the state.
4 No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.) Every sample that has total coliform must be analyzed for either fecal coliforms or E. coli if two consecutive TC-positive samples, and one is also positive for E.coli fecal coliforms, system has an acute MCL violation.
5 Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Disease-causing microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. These pathogens may pose a special health risk for infants, young children, and people with severely compromised immune systems.
6 Although there is no collective MCLG for this contaminant group, there are individual MCLGs for some of the individual contaminants:
- Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L): chloroform (0.07mg/L).
- Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.02 mg/L); monochloroacetic acid (0.07 mg/L). Bromoacetic acid and dibromoacetic acid are regulated with this group but have no MCLGs.
7 Lead and copper are regulated by a Treatment Technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L.
8 Each water system must certify, in writing, to the state (using third-party or manufacturer’s certification) that when acrylamide and epichlorohydrin are used to treat water, the combination (or product) of dose and monomer level does not exceed the levels specified, as follows:
- Acrylamide = 0.05% dosed at 1 mg/L (or equivalent)
- Epichlorohydrin = 0.01% dosed at 20 mg/L (or equivalent)
National Secondary Drinking Water Regulations
National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
- National Secondary Drinking Water Regulations - The complete regulations regarding these contaminants available from the Code of Federal Regulations Web Site.
- For more information, read Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.
| Contaminant | Secondary Standard |
|---|---|
| Aluminum | 0.05 to 0.2 mg/L |
| Chloride | 250 mg/L |
| Color | 15 (color units) |
| Copper | 1.0 mg/L |
| Corrosivity | noncorrosive |
| Fluoride | 2.0 mg/L |
| Foaming Agents | 0.5 mg/L |
| Iron | 0.3 mg/L |
| Manganese | 0.05 mg/L |
| Odor | 3 threshold odor number |
| pH | 6.5-8.5 |
| Silver | 0.10 mg/L |
| Sulfate | 250 mg/L |
| Total Dissolved Solids | 500 mg/L |
| Zinc | 5 mg/L |
Unregulated Contaminants
This list of contaminants which, at the time of publication, are not subject to any proposed or promulgated national primary drinking water regulation (NPDWR), are known or anticipated to occur in public water systems, and may require regulations under SDWA. For more information check out the list, or vist the Drinking Water Contaminant Candidate List (CCL) web site.
- Drinking Water Contaminant Candidate List 2
- Drinking Water Contaminant Candidate List (CCL) Web Site
- Unregulated Contaminant Monitoring Program (UCM)
- Information on specific unregulated contaminants
- MTBE (methyl-t-butyl ether) in drinking water
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