WSR 26-15-063
PERMANENT RULES
DEPARTMENT OF HEALTH
[Filed July 14, 2026, 11:30 a.m., effective August 14, 2026]
Effective Date of Rule: Thirty-one days after filing.
Purpose: Lead and copper rule improvements for Group A public water systems. The department of health (department) is adopting the federal requirements by text and reference for lead and copper rule revisions, and making minor editorial changes and updates to ensure consistency of terms and internal references in chapter 246-290 WAC between federal and state rules.
This adoption also makes editorial amendments and aligns the rule with the code reviser's 2025 Bill Drafting Guide.
Citation of Rules Affected by this Order: Amending WAC 246-290-025, 246-290-310, 246-290-72230, 246-290-72300, 246-290-72310, and 246-290-72400.
Statutory Authority for Adoption: RCW 43.20.250, 70A.125.080, and 70A.130.010.
Adopted under notice filed as WSR 26-11-039 on May 18, 2026.
Changes Other than Editing from Proposed to Adopted Version: A typographical error was corrected by changing the exclusion reference in WAC 246-290-025 from (j) to (i) for 141.82, Description of corrosion control treatment requirements.
Number of Sections Adopted in Order to Comply with Federal Statute: New 0, Amended 0, Repealed 0; Federal Rules or Standards: New 0, Amended 6, Repealed 0; or Recently Enacted State Statutes: New 0, Amended 0, Repealed 0.
Number of Sections Adopted at the Request of a Nongovernmental Entity: New 0, Amended 0, Repealed 0.
Number of Sections Adopted on the Agency's own Initiative: New 0, Amended 0, Repealed 0.
Number of Sections Adopted in Order to Clarify, Streamline, or Reform Agency Procedures: New 0, Amended 0, Repealed 0.
Number of Sections Adopted using Negotiated Rule Making: New 0, Amended 0, Repealed 0; Pilot Rule Making: New 0, Amended 0, Repealed 0; or Other Alternative Rule Making: New 0, Amended 6, Repealed 0.
Date Adopted: July 14, 2026.
Kristin Peterson, JD
Chief of Policy
for Dennis E. Worsham
Secretary of Health
RDS-7111.4
AMENDATORY SECTION(Amending WSR 26-08-023, filed 3/23/26, effective 4/23/26)
WAC 246-290-025Adoption by reference.
The following sections and subsections of Title 40 Code of Federal Regulations (C.F.R.) Part 141 National Primary Drinking Water Regulations and Part 143 National Secondary Drinking Water Regulations revised as of ((June 25))October 30, 2024, are adopted by reference:
141.2
Definitions. Only those definitions listed as follows:
 
Action level;
 
Aerator;
 
Child care facility;
 
Connector;
 
Corrosion inhibitor;
 
Distribution system and site assessment;
 
Effective corrosion inhibitor residual;
 
Elementary school;
 
Enhanced coagulation;
 
Enhanced softening;
 
First ((draw))liter sample;
 
Galvanized requiring replacement service line;
 
Galvanized service line;
 
Haloacetic acids (five) (HAA5);
 
Large water system;
 
Lead service line;
 
Lead status unknown service line;
 
Maximum residual disinfectant level (MRDL);
 
Maximum residual disinfectant level goal (MRDLG);
 
Medium((-size)) water system;
 
Method detection limit (MDL);
 
Newly regulated public water system;
 
Optimal corrosion control treatment (OCCT);
 
Partial service line replacement;
 
Pitcher filter;
 
Point-of-use treatment device or point-of-use device (POU);
 
Practical quantitation limit (PQL);
 
Prestagnation flushing;
 
School;
 
Secondary school;
 
Service line;
 
Single family structure;
 
Small water system;
 
Specific ultraviolet absorption (SUVA); ((and))
 
System without corrosion control treatment;
 
Tap monitoring period;
 
Tap sampling period;
 
Tap sampling protocol;
 
Total Organic Carbon (TOC); and
 
Wide-mouth bottles.
141.13
Maximum contaminant levels for turbidity.
141.22
Turbidity sampling and analytical requirements.
141.23 (a) through (j) and (m) through (o), excluding (i)(2), (k), and (l)
Inorganic chemical sampling and compliance.
141.24 (f)(1) through (15), (18), (19), (21), and (22)
Volatile organic monitoring and compliance.
141.24(h), excluding (13), (18), and (19)
Synthetic organic monitoring and compliance, except PFAS.
141.25 (a), (c), and (d)
Analytical methods for radioactivity.
141.26
Monitoring frequency and compliance for radionuclides in community water systems.
141.31(d)
Reporting requirements.
141.33(e)
Record maintenance.
141.40
Monitoring requirements for unregulated contaminants.
141.61
Maximum contaminant levels for organic contaminants.
141.62, excluding (b)
Maximum contaminant levels for inorganic contaminants.
141.63(e)
Maximum contaminant levels (MCLs) for microbiological contaminants.
141.64
Maximum contaminant levels for disinfection byproducts.
141.65(c)
Maximum Residual Disinfectant Levels.
141.66
Maximum contaminant levels for radionuclides.
Control of Lead and Copper
141.80((, excluding (c)(3)(v)))
General requirements.
141.81
Applicability of corrosion control treatment steps to small, medium-size and large water systems.
141.82 (((a) through (h))), excluding (i)
Description of corrosion control treatment requirements.
141.83
Source water treatment requirements.
141.84
Lead service line replacement requirements.
141.85
Public education and supplemental monitoring requirements.
141.86 (((a) through (f))), excluding (g)
Monitoring requirements for lead and copper in tap water.
141.87
Monitoring requirements for water quality parameters.
141.88
Monitoring requirements for lead and copper in source water.
141.89
Analytical methods.
141.90, excluding (((a)(4)))(j)(1)
Reporting requirements.
141.91
Recordkeeping requirements.
141.92
Monitoring for lead in schools and child care facilities.
141.93, excluding (c)(1)
Small water system compliance flexibility.
Disinfectants and Disinfection Byproducts (D/DBP)
141.130
General requirements.
141.131
Analytical requirements.
141.132, excluding (c)(1)(i)
Monitoring requirements.
141.133
Compliance requirements.
141.134
Reporting and recordkeeping requirements.
141.135
Treatment technique for control of disinfection byproduct precursors.
((Subpart O - Consumer Confidence Reports
141.153 (h)(8)(ii)
Contents of the reports.))
Enhanced Filtration and Disinfection - Systems Serving 10,000 or More People
141.175(b)
Reporting and recordkeeping requirements.
Subpart Q - Public Notification of Drinking Water Violations
141.201, excluding (3)(ii) of Table 1
General public notification requirements.
141.202, excluding (3) of Table 1
Tier 1 Public Notice - Form, manner, and frequency of notice.
141.203
Tier 2 Public Notice - Form, manner, and frequency of notice.
141.204
Tier 3 Public Notice - Form, manner, and frequency of notice.
141.205
Content of the public notice.
141.206
Notice to new billing units or new customers.
141.207
Special notice of the availability of unregulated contaminant monitoring results.
141.208
Special notice for exceedances of the SMCL for fluoride.
141.211
Special notice for repeated failure to conduct monitoring of the source water for Cryptosporidium and for failure to determine bin classification or mean Cryptosporidium level.
Appendix A to Subpart Q of Part 141
NPDWR violations and other situations requiring public notice.
Appendix B to Subpart Q of Part 141
Standard health effects language for public notification.
Appendix C to Subpart Q of Part 141
List of acronyms used in public notification regulation.
141.400
General requirements and applicability.
141.402(c)
Groundwater source microbial monitoring and analytical methods.
141.403 (b)(3)(i) through (iii)
Treatment technique requirements for groundwater systems.
Subpart T - Enhanced Filtration and Disinfection - Systems Serving Fewer Than 10,000 People
141.530 through 141.544
Disinfection profile and benchmark.
141.563
What follow-up action is my system required to take based on continuous turbidity monitoring?
141.570, excluding (c)
What does Subpart T require that my system report to the state?
Subpart U - Initial Distribution System Evaluations
141.600 through 141.605
Initial distribution system evaluations.
Subpart V - Stage 2 Disinfection Byproducts Requirements
141.620 through 141.629, excluding 141.624
Stage 2 Disinfection Byproducts Requirements.
Subpart W - Enhanced Treatment for Cryptosporidium
141.700 through 141.722
Enhanced Treatment for Cryptosporidium.
Subpart Y - Revised Total Coliform Rule
141.852
Analytical methods and laboratory certification.
141.860 (c) and (d)
Violations.
Subpart Z - Control of Per- and Polyfluoroalkyl Substances (PFAS)
141.904
Reporting and recordkeeping requirements.
141.905
Violations.
Part 143 - National Secondary Drinking Water Regulations
143.1
Purpose.
143.2
Definitions.
143.3
Secondary maximum contaminant levels.
143.4
Monitoring.
Copies of the incorporated sections and subsections of Title 40 C.F.R. are available from the Department of Health online at: https://doh.wa.gov/Community-and-Environment/Drinking-Water/Regulation-and-Compliance/Rules, or P.O. Box 47822, Olympia, Washington 98504-7822, or by calling the department's drinking water hotline at 800-521-0323.
AMENDATORY SECTION(Amending WSR 26-08-023, filed 3/23/26, effective 4/23/26)
WAC 246-290-72230Report contents—Information on detected contaminants.
This section takes effect on January 1, 2027.
(1) This section specifies the requirements for information to be included in each report for contaminants subject to mandatory monitoring. It applies to:
(a) Contaminants subject to an MCL, federal action level, SAL, TT, or MRDL (regulated contaminants); and
(b) Detected contaminants without an MCL, federal action level, SAL, TT, or MRDL for which monitoring is required.
(2) The data relating to these contaminants must be presented in the reports in a manner that is clear and understandable for consumers. For example, the data may be displayed in one table or in several adjacent tables. Any additional monitoring results which a community water system chooses to include in its report must be displayed separately.
(3)(a) Except under (b) of this subsection, the data must be derived from data collected to comply with EPA and state monitoring and analytical requirements during the previous calendar year, or the most recent calendar year before the previous calendar year.
(b) When a system is allowed to monitor for regulated contaminants less than once a year, the contaminant data section must include the date and results of the most recent sampling and the report must include a brief statement indicating that the data presented in the report are from the most recent testing done in accordance with the regulations.
(c) No data older than five years need be included.
(4) For each detected regulated contaminant listed in WAC 246-290-72400, the contaminant data section(s) must contain:
(a) The MCL or SAL for that contaminant expressed as a number equal to or greater than 1.0 (as provided in WAC 246-290-72400);
(b) The MCLG for that contaminant expressed in the same units as the MCL;
(c) If there is no MCL or SAL for a detected contaminant, the contaminant data section(s) must indicate that there is a treatment technique, or specify the action level, applicable to that contaminant, and the report must include the definitions for treatment technique, action level, or both, as appropriate, specified in WAC 246-290-72220;
(d) Except for turbidity and E. coli, the contaminant data section(s) for contaminants with an MCL or SAL must contain the highest contaminant level used to determine compliance with a SAL or a National Primary Drinking Water Regulation and the range of results, as follows:
(i) When compliance with the MCL or SAL is determined annually or less frequently: The highest detected level at any sampling location and the range of results expressed in the same units as the MCL or SAL.
(ii) When compliance with the MCL or SAL is determined by calculating a running annual average of all samples taken at a sampling location: The highest average of any of the sampling locations and the range of individual sample results for all sampling locations expressed in the same units as the MCL or SAL. For the TTHM and HAA5 MCLs determined on the basis of the LRAA, systems must include the highest LRAA for TTHM and HAA5 and the range of individual sample results for all monitoring locations expressed in the same units as the MCL. If more than one location exceeds the TTHM or HAA5 MCL, the system must include the LRAA for all locations that exceed the MCL.
(iii) When rounding of results to determine compliance with the MCL or SAL is allowed by the regulations, rounding should be done prior to multiplying the results by the factor listed in WAC 246-290-72400;
(e) For turbidity:
(i) When it is reported under WAC 246-290-670 through 246-290-678: The highest average monthly value.
(ii) When it is reported under the requirements of WAC 246-290-686 through 246-290-696: The highest monthly value. The report should include an explanation of the reasons for measuring turbidity.
(iii) When it is reported under WAC 246-290-650 through 246-290-668: The highest single measurement and the lowest monthly percentage of samples meeting the turbidity limits specified in WAC 246-290-650 through 246-290-668 for the filtration technology being used. The report should include an explanation of the reasons for measuring turbidity;
(f) For lead and copper: The 90th percentile value of the most recent round(s) of sampling and the number of sampling sites exceeding the action level, and the range of tap sampling results;
(g) For E. coli analytical results under WAC 246-290-300 (3)(e) through (g): The total number of positive samples; and
(h) The likely source(s) of detected contaminants to the best of the purveyor's knowledge. Specific information regarding contaminants may be available in sanitary surveys and source water assessments, and should be used when available to the purveyor. If the purveyor lacks specific information on the likely source, the report must include one or more of the typical sources for that contaminant listed in WAC 246-290-72400 that are most applicable to the system.
(5) If a community water system distributes water to its customers from multiple hydraulically independent distribution systems that are fed by different raw water sources, the contaminant data section(s) should differentiate contaminant data for each service area and the report should identify each separate distribution system. For example, if displayed in a table, it should contain a separate column for each service area. Alternatively, systems could produce separate reports tailored to include data for each service area.
(6)(a) The detected contaminant data section(s) must clearly identify any data indicating violations of MCLs, MRDLs, or treatment techniques.
(b) The report must contain a clear and readily understandable explanation of each violation including:
(i) The length of the violation;
(ii) The potential adverse health effects using the relevant language of WAC 246-290-72400; and
(iii) Actions taken by the system to address the violation.
(7) Detected contaminants without an MCL, SAL, federal action level, TT, or MRDL for which monitoring is required, the reports must present the average and range at which the contaminant was detected. The report must include a brief explanation of the reasons for monitoring for unregulated contaminants such as:
(a) Unregulated contaminant monitoring helps EPA to determine where certain contaminants occur and whether EPA should consider regulating those contaminants in the future.
(b) An alternative educational statement approved by the department.
(8) For systems that exceeded the lead action level in 40 C.F.R. 141.80(c) as adopted under WAC 246-290-025:
(a) The detected contaminant data section must clearly identify the exceedance if any corrective action has been required by EPA or the department during the monitoring period covered by the report.
(b) The report must include:
(i) A clear and readily understandable explanation of the exceedance;
(ii) The steps consumers can take to reduce their exposure to lead in drinking water; and
(iii) A description of any corrective actions the system has or will take to address the exceedance.
AMENDATORY SECTION(Amending WSR 26-08-023, filed 3/23/26, effective 4/23/26)
WAC 246-290-72300Report contents—Lead and copper.
This section takes effect on January 1, 2027. This section applies to systems subject to 40 C.F.R. 141 Subpart I.
(1) The report must notify consumers that complete lead tap sampling data are available for review and must include information on how to access the data.
(2) The report must include a statement that a service line inventory (including inventories consisting only of a statement that there are no lead, galvanized requiring replacement, or lead status unknown service lines, known lead connectors or connectors of unknown material) has been prepared and include instructions to access the publicly available service line inventory. If the service line inventory is available online, the report must include the direct link to the inventory.
(3) For systems with lead, galvanized requiring replacement, or lead status unknown service lines in the system's inventory pursuant to 40 C.F.R.  141.84 (a) and (b), the report must include information on how to obtain a copy of the service line replacement plan or a direct link to the plan if the system is required to make the service line replacement plan available online. 
(4) The report must contain a plainly worded explanation of the corrosion control efforts the system is taking in accordance with 40 C.F.R. 141 Subpart I. Corrosion control efforts consist of treatment (e.g., pH adjustment, alkalinity adjustment, or corrosion inhibitor addition) and other efforts contributing to the control of the corrosivity of water, e.g., monitoring to assess the corrosivity of water. The system may use one of the following templates or use their own explanation that includes equivalent information.
(a) For systems with state or EPA-designated Optimal Corrosion Control Treatment:
(i) Corrosion of pipes, plumbing fittings and fixtures may cause lead and copper to enter drinking water. To assess corrosion of lead and copper, (NAME OF SYSTEM) conducts tap sampling for lead and copper at selected sites (INSERT FREQUENCY AT WHICH SYSTEM CONDUCTS TAP SAMPLING). (NAME OF SYSTEM) treats water using (IDENTIFY TREATMENT METHOD) to control corrosion, which was designated as the optimal corrosion control treatment by (THE STATE OR EPA, AS APPLICABLE). To ensure the treatment is operating effectively, (NAME OF SYSTEM) monitors water quality parameters set by (THE STATE OR EPA, AS APPLICABLE) (INSERT FREQUENCY AT WHICH SYSTEM CONDUCTS WATER QUALITY PARAMETER MONITORING).
(ii) If applicable, add: (NAME OF SYSTEM) is currently conducting a study of corrosion control to determine if any changes to treatment methods are needed to minimize the corrosivity of the water.
(b) For systems without state or EPA designated Optimal Corrosion Control Treatment:
(i) Corrosion of pipes, plumbing fittings, and fixtures may cause metals, including lead and copper, to enter drinking water. To assess corrosion of lead and copper, (NAME OF SYSTEM) conducts tap sampling for lead and copper at selected sites (INSERT FREQUENCY AT WHICH SYSTEM CONDUCTS TAP SAMPLING).
(ii) If applicable, add: (NAME OF SYSTEM) treats water using (IDENTIFY TREATMENT METHOD) to control corrosion.
(iii) If applicable, add: (NAME OF SYSTEM) is currently conducting a study of corrosion control to determine if any changes to treatment methods are needed to minimize the corrosivity of the water.
(5) The report must include a statement that the water system is  required  to sample for lead in schools and licensed  child care  facilities as requested by the facility and that directs the public to contact their school or  child care  facility for further information about potential sampling results.
AMENDATORY SECTION(Amending WSR 26-08-023, filed 3/23/26, effective 4/23/26)
WAC 246-290-72350Report contents—Required additional health information.
This section takes effect on January 1, 2027. All reports must prominently display the following language: Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised people such as people with cancer undergoing chemotherapy, people who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. Environmental Protection Agency/Centers for Disease Control guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline (800-426-4791) or on EPA's website epa.gov/safewater.
(1) A system that detects arsenic levels above 0.005 mg/L and up to and including 0.010 mg/L:
(a) Must include in its report a short informational statement about arsenic, using language such as: Arsenic is known to cause cancer in humans. Arsenic also may cause other health effects such as skin damage and circulatory problems. (NAME OF SYSTEM) meets the EPA arsenic drinking water standard, also known as a Maximum Contaminant Level (MCL). However, you should know that EPA's MCL for arsenic balances the scientific community's understanding of arsenic-related health effects and the cost of removing arsenic from drinking water. The highest concentration of arsenic found in (YEAR) was (INSERT MAX ARSENIC LEVEL UNDER WAC 246-290-72230 (4)(d)) ppb.
(b) May use an alternative educational statement approved by the department.
(2) A system that detects nitrate at levels above 5 mg/L, but below the MCL:
(a) Must include a short informational statement about the impacts of nitrate on children using language such as: Even though (NAME OF SYSTEM) meets the EPA nitrate drinking water standard, also known as a Maximum Contaminant Level (MCL), if you are caring for an infant and using tap water to prepare formula, you may want to use alternate sources of water or ask for advice from your health care provider. Nitrate levels above 10 ppm pose a particularly high health concern for infants under six months of age and can interfere with the capacity of the infant's blood to carry oxygen, resulting in a serious illness. Symptoms of serious illness include shortness of breath and blueness of the skin, known as "blue baby syndrome." Nitrate levels in drinking water increase for short periods of time due to high levels of rainfall or agricultural activity, therefore we test for nitrate (INSERT APPLICABLE SAMPLING FREQUENCY). The highest level for nitrate found during (YEAR) was (INSERT MAX NITRATE LEVEL UNDER WAC 246-290-72230 (4)(d)) ppm.
(b) May use an alternative educational statement approved by the department.
(3) All reports must include a short informational statement about lead in drinking water and its effects on children.
(a) The statement must include the following information: ((If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. (NAME OF SYSTEM) is responsible for providing high quality drinking water, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to two minutes before using water for drinking or cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or))Lead can cause serious health effects in people of all ages, especially pregnant people, infants (both formula-fed and breastfed), and young children. Lead in drinking water is primarily from materials and parts used in service lines and in home plumbing. (INSERT NAME OF SYSTEM) is responsible for providing high quality drinking water and removing lead pipes but cannot control the variety of materials used in the plumbing in your home. Because lead levels may vary over time, lead exposure is possible even when your tap sampling results do not detect lead at one point in time. You can help protect yourself and your family by identifying and removing lead materials within your home plumbing and taking steps to reduce your family's risk. Using a filter, certified by an American National Standards Institute accredited certifier to reduce lead, is effective in reducing lead exposures. Follow the instructions provided with the filter to ensure the filter is used properly. Use only cold water for drinking, cooking, and making baby formula. Boiling water does not remove lead from water. Before using tap water for drinking, cooking, or making baby formula, flush your pipes for several minutes. You can do this by running your tap, taking a shower, doing laundry, or a load of dishes. If you have a lead service line or galvanized requiring replacement service line, you may need to flush your pipes for a longer period. If you are concerned about lead in your water and wish to have your water tested, contact (INSERT NAME OF SYSTEM and CONTACT INFORMATION). Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available at http://www.epa.gov/safewater/lead.
(b) A system may write its own educational statement, but only in consultation with the department.
AMENDATORY SECTION(Amending WSR 26-08-023, filed 3/23/26, effective 4/23/26)
WAC 246-290-72400Regulated contaminants.
Contaminant
MCL or SAL
(units match lab results)
To convert
lab results
for CCR,
multiply by
MCL or
SAL in
CCR units
MCLG in CCR units
Major Sources in
Drinking Water
Health Effects Language
Microbiological Contaminants
Total Coliform Bacteria
TT
-
TT
0
Naturally present in the environment
Coliforms are bacteria that are naturally present in the environment and are used as an indicator that other, potentially harmful, waterborne pathogens may be present or that a potential pathway exists through which contamination may enter the drinking water distribution system. We found coliforms indicating the need to look for potential problems in water treatment or distribution. When this occurs, we are required to conduct assessment(s) to identify problems and to correct any problems that were found during these assessments.
E. coli
Routine and repeat samples are total coliform-positive and either is E. coli-positive or system fails to take repeat samples following E. coli-positive routine sample or system fails to analyze total coliform-positive repeat sample for E. coli.
-
Routine and repeat samples are total coliform-positive and either is E. coli-positive or system fails to take repeat samples following E. coli-positive routine sample or system fails to analyze total coliform-positive repeat sample for E. coli.
0
Human and animal fecal waste
E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Human pathogens in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms. They may pose a greater health risk for infants, young children, the elderly, and people with severely-compromised immune systems.
((Fecal indicators (E. coli)
TT
-
TT
0
Human and animal fecal waste
Fecal indicators are microbes whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes can cause short-term health effects, such as diarrhea, cramps, nausea, headaches, or other symptoms. They may pose a special health risk for infants, young children, some of the elderly, and people with severely compromised immune systems.))
Total organic carbon
TT
-
TT
N/A
Naturally present in the environment
Total organic carbon (TOC) has no health effects. However, total organic carbon provides a medium for the formation of disinfection byproducts. These byproducts include trihalomethanes (THMs) and haloacetic acids (HAAs). Drinking water containing these byproducts in excess of the MCL may lead to adverse health effects, liver or kidney problems, or nervous system effects, and may lead to an increased risk of getting cancer.
Turbidity
TT
-
TT
N/A
Soil runoff
Turbidity has no health effects. However, turbidity can interfere with disinfection and provide a medium for microbial growth. Turbidity may indicate the presence of disease-causing organisms. These organisms include bacteria, viruses, and parasites that can cause symptoms such as nausea, cramps, diarrhea and associated headaches.
Giardia lamblia Viruses Cryptosporidium
TT
-
TT
0
Human and animal fecal waste
Inadequately treated water may contain disease-causing organisms. These organisms include bacteria viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.
Heterotrophic plate count (HPC) bacteria
TT
-
TT
N/A
HPC measures a range of bacteria that are naturally present in the environment
Inadequately treated water may contain disease-causing organisms. These organisms include bacteria viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.
Legionella
TT
-
TT
0
Found naturally in water; multiplies in heating systems
Inadequately treated water may contain disease-causing organisms. These organisms include bacteria viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.
Radioactive Contaminants
Beta/photon emitters
4 mrem/yr
-
4 mrem/yr
0
Decay of natural and man-made deposits
Certain minerals are radioactive and may emit forms of radiation known as photons and beta radiation. Some people who drink water containing beta and photon emitters in excess of the MCL over many years may have an increased risk of getting cancer.
Alpha emitters [gross alpha excluding uranium and radon]
15 pCi/l
-
15 (pCi/L)
0
Erosion of natural deposits
Certain minerals are radioactive and may emit a form of radiation known as alpha radiation. Some people who drink water containing alpha emitters in excess of the MCL over many years may have an increased risk of getting cancer.
Combined radium [226 & 228]
5 pCi/l
-
5 (pCi/L)
0
Erosion of natural deposits
Some people who drink water containing radium 226 or 228 in excess of the MCL over many years may have an increased risk of getting cancer.
Uranium
30 ppb
-
30 ppb
0
Erosion of natural deposits
Some people who drink water containing uranium in excess of the MCL over many years may have an increased risk of getting cancer and kidney toxicity.
Inorganic Contaminants
Antimony
.006 ppm
1000
6 ppb
6 ppb
Discharge from petroleum refineries; fire retardants; ceramics; electronics; solder
Some people who drink water containing antimony well in excess of the MCL over many years could experience increases in blood cholesterol and decreases in blood sugar.
Arsenic
0.010 ppm
1000
10 ppb
0
Erosion of natural deposits; Runoff from orchards; Runoff from glass and electronics production wastes
Some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.
Asbestos
7 MFL
-
7 MFL
7 MFL
Decay of asbestos cement water mains; Erosion of natural deposits
Some people who drink water containing asbestos in excess of the MCL over many years may have an increased risk of developing benign intestinal polyps.
Barium
2 ppm
-
2 ppm
2 ppm
Discharge of drilling wastes; Discharge from metal refineries; Erosion of natural deposits
Some people who drink water containing barium in excess of the MCL over many years could experience an increase in their blood pressure.
Beryllium
.004 ppm
1000
4 ppb
4 ppb
Discharge from metal refineries and coal-burning factories; Discharge from electrical, aerospace, and defense industries
Some people who drink water containing beryllium well in excess of the MCL over many years could develop intestinal lesions.
Cadmium
.005 ppm
1000
5 ppb
5 ppb
Corrosion of galvanized pipes; Erosion of natural deposits; Discharge from metal refineries; Runoff from waste batteries and paints
Some people who drink water containing cadmium in excess of the MCL over many years could experience kidney damage.
Chromium
.1 ppm
1000
100 ppb
100 ppb
Discharge from steel and pulp mills; Erosion of natural deposits
Some people who use water containing chromium well in excess of the MCL over many years could experience allergic dermatitis.
Copper
TT
AL = 1.3 ppm
-
TT
AL = 1.3 ppm
1.3 ppm
Corrosion of household plumbing systems; Erosion of natural deposits
Copper is an essential nutrient, but some people who drink water containing copper in excess of the action level over a relatively short amount of time could experience gastrointestinal distress. Some people who drink water containing copper in excess of the action level over many years could suffer liver or kidney damage. People with Wilson's Disease should consult their personal doctor.
Cyanide
.2 ppm
1000
200 ppb
200 ppb
Discharge from steel/metal factories; Discharge from plastic and fertilizer factories
Some people who drink water containing cyanide well in excess of the MCL over many years could experience nerve damage or problems with their thyroid.
Fluoride
4 ppm
-
4 ppm
4 ppm
Erosion of natural deposits; Water additive which promotes strong teeth; Discharge from fertilizer and aluminum factories
Some people who drink water containing fluoride in excess of the MCL over many years could get bone disease, including pain and tenderness of the bones. Fluoride in drinking water at half the MCL or more may cause mottling of children's teeth, usually in children less than nine years old. Mottling, also known as dental fluorosis, may include brown staining and/or pitting of the teeth, and occurs only in developing teeth before they erupt from the gums.
Lead
TT
AL = ((.015)).010 ppm
1000
TT
AL = ((15))10 ppb
0
Corrosion of household plumbing systems((;))and service lines connecting buildings to water mains, erosion of natural deposits.
((Infants and children who drink water containing lead in excess of the action level could experience delays in their physical or mental development. Children could show slight deficits in attention span and learning abilities. Adults who drink this water over many years could develop kidney problems or high blood pressure.))There is no safe level of lead in drinking water. Exposure to lead in drinking water can cause serious health effects in all age groups, especially pregnant people, infants (both formula-fed and breastfed), and young children. Some of the health effects to infants and children include decreases in IQ and attention span. Lead exposure can also result in new or worsened learning and behavior problems. The children of persons who are exposed to lead before or during pregnancy may be at increased risk of these harmful health effects. Adults have increased risks of heart disease, high blood pressure, kidney, or nervous system problems.
Mercury [inorganic]
.002 ppm
1000
2 ppb
2 ppb
Erosion of natural deposits; Discharge from refineries and factories; Runoff from landfills; Runoff from cropland
Some people who drink water containing inorganic mercury well in excess of the MCL over many years could experience kidney damage.
Nitrate
 
-
10.0 ppm
10.0 ppm
Runoff from fertilizer use; Leaching from septic tanks, sewage; Erosion of natural deposits
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.
Nitrite
1.0 ppm
-
1.0 ppm
1.0 ppm
Runoff from fertilizer use; Leaching from septic tanks, sewage; Erosion of natural deposits
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.
Selenium
.05 ppm
1000
50 ppb
50 ppb
Discharge from petroleum and metal refineries; Erosion of natural deposits; Discharge from mines
Selenium is an essential nutrient. However, some people who drink water containing selenium in excess of the MCL over many years could experience hair or fingernail losses, numbness in fingers or toes, or problems with their circulation.
Thalium
.002 ppm
1000
2 ppb
0.5 ppb
Leaching from ore-processing sites; Discharge from electronics, glass, and drug factories
Some people who drink water containing thallium in excess of the MCL over many years could experience hair loss, changes in their blood, or problems with their kidneys, intestines, or liver.
Disinfection Byproducts (DBPs)
Bromate
.010 ppm
1000
10 ppb
0
Byproduct of drinking water disinfection
Some people who drink water containing bromate in excess of the MCL over many years may have an increased risk of getting cancer.
Chloramines
MRDL = 4 ppm
-
MRDL = 4 ppm
MRDLG = 4 ppm
Water additive used to control microbes
Some people who use drinking water containing chloramines well in excess of the MRDL could experience irritating effects to their eyes and nose. Some people who drink water containing chloramines well in excess of the MRDL could experience stomach discomfort or anemia.
Chlorine
MRDL = 4 ppm
-
MRDL = 4 ppm
MRDLG = 4 ppm
Water additive used to control microbes
Some people who use drinking water containing chlorine well in excess of the MRDL could experience irritating effects to their eyes and nose. Some people who drink water containing chlorine well in excess of the MRDL could experience stomach discomfort.
Chlorite
1 ppm
-
1 ppm
0.8 ppm
Byproduct of drinking water disinfection
Some infants and young children who drink water containing chlorite in excess of the MCL could experience nervous system effects. Similar effects may occur in fetuses of pregnant mothers who drink water containing chlorite in excess of the MCL. Some people may experience anemia.
Chlorine dioxide
MRDL =
.8 ppm
1000
MRDL = 800 ppb
MRDLG = 800 ppb
Water additive used to control microbes
Some infants and young children who drink water containing chlorine dioxide in excess of the MRDL could experience nervous system effects. Similar effects may occur in fetuses of pregnant mothers who drink water containing chlorine dioxide in excess of the MRDL. Some people may experience anemia.
Haloacetic Acids (HAA5)
60 ppb
-
60 ppb
N/A for combined dichloroacetic acid = 0; monochloroacetic acid = 70 ppb; trichloroacetic acid = 20 ppb
Byproduct of drinking water disinfection
Some people who drink water containing haloacetic acids in excess of the MCL over many years may have an increased risk of getting cancer.
Total Trihalomethanes [TTHMs]
80 ppb
-
80 ppb
N/A
(chloroform = 70 ppb; dibromochloromethane = 60 ppb; bromoform = 0; bromodichloromethane = 0)
Byproduct of drinking water disinfection
Some people who drink water containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous systems, and may have an increased risk of getting cancer.
Synthetic Organic Contaminants including Pesticides and Herbicides, except PFAS
2,4-D
70 ppb
-
70 ppb
70 ppb
Runoff from herbicide used on row crops
Some people who drink water containing the weed killer 2,4-D well in excess of the MCL over many years could experience problems with their kidneys, liver, or adrenal glands.
2,4,5-TP [Silvex]
50 ppb
-
50 ppb
50 ppb
Residue of banned herbicide
Some people who drink water containing silvex in excess of the MCL over many years could experience liver problems.
Alachlor
2 ppb
-
2 ppb
0
Runoff from herbicide used on row crops
Some people who drink water containing alachlor in excess of the MCL over many years could have problems with their eyes, liver, kidneys, or spleen, or experience anemia, and may have an increased risk of getting cancer.
Atrazine
3 ppb
-
3 ppb
3 ppb
Runoff from herbicide used on row crops
Some people who drink water containing atrazine well in excess of the MCL over many years could experience problems with their cardiovascular system or reproductive difficulties.
Benzo(a)pyrene [PAH]
.2 ppb
1000
200 ppt
0
Leaching from linings of water storage tanks and distribution lines
Some people who drink water containing benzo(a)pyrene in excess of the MCL over many years may experience reproductive difficulties and may have an increased risk of getting cancer.
Carbofuran
40 ppb
-
40 ppb
40 ppb
Leaching of soil fumigant used on rice and alfalfa
Some people who drink water containing carbofuran in excess of the MCL over many years could experience problems with their blood, or nervous or reproductive systems.
Chlordane
2 ppb
-
2 ppb
0
Residue of banned termiticide
Some people who drink water containing chlordane in excess of the MCL over many years could experience problems with their liver or nervous system, and may have an increased risk of getting cancer.
Dalapon
200 ppb
-
200 ppb
200 ppb
Runoff from herbicide used on rights of way
Some people who drink water containing dalapon well in excess of the MCL over many years could experience minor kidney changes.
Di(2-ethylhexyl) adipate
400 ppb
-
400 ppb
400 ppb
Discharge from chemical factories
Some people who drink water containing di (2-ethylhexyl) adipate well in excess of the MCL over many years could experience toxic effects or reproductive difficulties.
Di(2-ethylhexyl) phthalate
6 ppb
-
6 ppb
0
Discharge from rubber and chemical factories
Some people who drink water containing di (2-ethylhexyl) phthalate well in excess of the MCL over many years may have problems with their liver, or experience reproductive difficulties, and may have an increased risk of getting cancer.
Dibromochloropropane [DBCP]
.2 ppb
1000
200 ppt
0
Runoff/leaching from soil fumigant used on soybeans, cotton, pineapples, and orchards
Some people who drink water containing DBCP in excess of the MCL over many years could experience reproductive problems and may have an increased risk of getting cancer.
Dinoseb
7 ppb
-
7 ppb
7 ppb
Runoff from herbicide used on soybeans and vegetables
Some people who drink water containing dinoseb well in excess of the MCL over many years could experience reproductive difficulties.
Dioxin [2,3,7,8-TCDD]
.03 ppt
1,000
30 ppb
0
Emissions from waste incineration and other combustion; Discharge from chemical factories
Some people who drink water containing dioxin in excess of the MCL over many years could experience reproductive difficulties and may have an increased risk of getting cancer.
Diquat
.02 ppb
1000
20 ppt
20 ppt
Runoff from herbicide use
Some people who drink water containing diquat in excess of the MCL over many years could get cataracts.
Endothall
100 ppb
-
100 ppb
100 ppb
Runoff from herbicide use
Some people who drink water containing endothall in excess of the MCL over many years could experience problems with their stomach or intestines.
Endrin
2 ppb
-
2 ppb
2 ppb
Residue of banned insecticide
Some people who drink water containing endrin in excess of the MCL over many years could experience liver problems.
Ethylene dibromide
.05 ppb
1000
50 ppt
0
Discharge from petroleum refineries
Some people who drink water containing ethylene dibromide in excess of the MCL over many years could experience problems with their liver, stomach, reproductive system, or kidneys, and may have an increased risk of getting cancer.
Glyphosate
700 ppb
-
700 ppb
700 ppb
Runoff from herbicide use
Some people who drink water containing glyphosate in excess of the MCL over many years could experience problems with their kidneys or reproductive difficulties.
Heptachlor
.4 ppb
1000
400 ppt
0
Residue of banned pesticide
Some people who drink water containing heptachlor in excess of the MCL over many years could experience liver damage and may have an increased risk of getting cancer.
Heptachlor epoxide
.2 ppb
1000
200 ppt
0
Breakdown of heptachlor
Some people who drink water containing heptachlor epoxide in excess of the MCL over many years could experience liver damage, and may have an increased risk of getting cancer.
Hexachlorobenzene
1 ppb
-
1 ppb
0
Discharge from metal refineries and agricultural chemical factories
Some people who drink water containing hexachlorobenzene in excess of the MCL over many years could experience problems with their liver or kidneys, or adverse reproductive effects, and may have an increased risk of getting cancer.
Hexachlorocyclo-pentadiene
50 ppb
-
50 ppb
50 ppb
Discharge from chemical factories
Some people who drink water containing hexachlorocyclopentadiene well in excess of the MCL over many years could experience problems with their kidneys or stomach.
Lindane
.2 ppb
1000
200 ppt
200 ppt
Runoff/leaching from insecticide used on cattle, lumber, gardens
Some people who drink water containing lindane in excess of the MCL over many years could experience problems with their kidneys or liver.
Methoxychlor
40 ppb
-
40 ppb
40 ppb
Runoff/leaching from insecticide used on fruits, vegetables, alfalfa, livestock
Some people who drink water containing methoxychlor in excess of the MCL over many years could experience reproductive difficulties.
Oxamyl [Vydate]
200 ppb
-
200 ppb
200 ppb
Runoff/leaching from insecticide used on apples, potatoes and tomatoes
Some people who drink water containing oxamyl in excess of the MCL over many years could experience slight nervous system effects.
PCBs [Polychlorinated biphenyls]
.5 ppb
1000
500 ppt
0
Runoff from landfills; Discharge of waste chemicals
Some people who drink water containing PCBs in excess of the MCL over many years could experience changes in their skin, problems with their thymus gland, immune deficiencies, or reproductive or nervous system difficulties, and may have an increased risk of getting cancer.
Pentachlorophenol
1 ppb
-
1 ppb
0
Discharge from wood preserving factories
Some people who drink water containing pentachlorophenol in excess of the MCL over many years could experience problems with their liver or kidneys, and may have an increased risk of getting cancer.
Picloram
500 ppb
-
500 ppb
500 ppb
Herbicide runoff
Some people who drink water containing picloram in excess of the MCL over many years could experience problems with their liver.
Simazine
4 ppb
-
4 ppb
4 ppb
Herbicide runoff
Some people who drink water containing simazine in excess of the MCL over many years could experience problems with their blood.
Toxaphene
3 ppb
-
3 ppb
0
Runoff/leaching from insecticide used on cotton and cattle
Some people who drink water containing toxaphene in excess of the MCL over many years could have problems with their kidneys, liver, or thyroid, and may have an increased risk of getting cancer.
Synthetic Organic Contaminants - PFAS
HFPO-DA
10 ppt
-
10 ppt
10 ppt
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing HFPO-DA in excess of the MCL over many years may have increased health risks such as immune, liver, and kidney effects. There is also a potential concern for cancer associated with HFPO-DA exposure. In addition, there may be increased risks of developmental effects for people who drink water containing HFPO-DA in excess of the MCL following repeated exposure during pregnancy and/or childhood.
PFOA
((10 ppt (SAL, effective for CCRs until 4/26/27)))
4.0 ppt (((MCL, effective for CCRs starting 4/26/27)))
-
((10 ppt (SAL, effective for CCRs until 4/26/27)))
4.0 ppt (((MCL, effective for CCRs starting 4/26/27)))
0 ppt
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing PFOA in excess of the MCL over many years may have increased health risks such as cardiovascular, immune, and liver effects, as well as increased incidence of certain types of cancers including kidney and testicular cancer. In addition, there may be increased risks of developmental and immune effects for people who drink water containing PFOA in excess of the MCL following repeated exposure during pregnancy and/or childhood.
PFOS
((15 ppt (SAL, effective for CCRs until 4/26/27)))
4.0 ppt (((MCL, effective for CCRs starting 4/26/27)))
-
((15 ppt (SAL, effective for CCRs until 4/26/27)))
4.0 ppt (((MCL, effective for CCRs starting 4/26/27)))
0 ppt
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing PFOS in excess of the MCL over many years may have increased health risks such as cardiovascular, immune, and liver effects, as well as increased incidence of certain types of cancers including liver cancer. In addition, there may be increased risks of developmental and immune effects for people who drink water containing PFOS in excess of the MCL following repeated exposure during pregnancy and/or childhood.
PFHxS
((65 ppt (SAL, effective for CCRs until 4/26/27)))
10 ppt (((MCL, effective for CCRs starting 4/26/27)))
-
((65 ppt (SAL, effective for CCRs until 4/26/27)))
10 ppt (((MCL, effective for CCRs starting 4/26/27)))
10 ppt
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing PFHxS in excess of the MCL over many years may have increased health risks such as immune, thyroid, and liver effects. In addition there may be increased risks of developmental effects for people who drink water containing PFHxS in excess of the MCL following repeated exposure during pregnancy and/or childhood.
PFNA
((9 ppt (SAL, effective for CCRs until 4/26/27)))
10 ppt (((MCL, effective for CCRs starting 4/26/27)))
-
((9 ppt (SAL, effective for CCRs until 4/26/27)))
10 ppt (((MCL, effective for CCRs starting 4/26/27)))
10 ppt
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing PFNA in excess of the MCL over many years may have increased health risks such as elevated cholesterol levels, immune effects, and liver effects. In addition, there may be increased risks of developmental effects for people who drink water containing PFNA in excess of the MCL following repeated exposure during pregnancy and/or childhood.
((PFBS
345 ppt (SAL, effective for CCRs until 4/26/27)
MCL is part of Hazard Index as of 4/26/27)
-
345 ppt (SAL, effective for CCRs until 4/26/27)
MCL is part of Hazard Index as of 4/26/27)
-
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Some people who drink water containing PFBS in excess of the SAL may experience higher risk of cholesterol, liver, kidney or thyroid problems. Early life is the most sensitive period for altered thyroid hormone; sensitive populations include persons who are pregnant, nursing or less than a year old.))
Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA)
1
(unitless)
-
1
(unitless)
1
(unitless)
Discharge from manufacturing and industrial chemical facilities, use of certain consumer products, occupational exposures, and certain firefighting activities
Per- and polyfluoroalkyl substances (PFAS) can persist in the human body and exposure may lead to increased risk of adverse health effects. Low levels of multiple PFAS that individually would not likely result in increased risk of adverse health effects may result in adverse health effects when combined in a mixture. Some people who consume drinking water containing mixtures of PFAS in excess of the Hazard Index (HI) MCL may have increased health risks such as liver, immune, and thyroid effects following exposure over many years and developmental and thyroid effects following repeated exposure during pregnancy and/or childhood.
Volatile Organic Contaminants
Benzene
5 ppb
-
5 ppb
0
Discharge from factories; Leaching from gas storage tanks and landfills
Some people who drink water containing benzene in excess of the MCL over many years could experience anemia or a decrease in blood platelets, and may have an increased risk of getting cancer.
Carbon tetrachloride
5 ppb
-
5 ppb
0
Discharge from chemical plants and other industrial activities
Some people who drink water containing carbon tetrachloride in excess of the MCL over many years could experience problems with their liver and may have an increased risk of getting cancer.
Chlorobenzene
100 ppb
-
100 ppb
100 ppb
Discharge from chemical and agricultural chemical factories
Some people who drink water containing chlorobenzene in excess of the MCL over many years could experience problems with their liver or kidneys.
o-Dichlorobenzene
600 ppb
-
600 ppb
600 ppb
Discharge from industrial chemical factories
Some people who drink water containing o-dichlorobenzene well in excess of the MCL over many years could experience problems with their liver, kidneys, or circulatory systems.
p-Dichlorobenzene
75 ppb
-
75 ppb
75 ppb
Discharge from industrial chemical factories
Some people who drink water containing p-dichlorobenzene in excess of the MCL over many years could experience anemia, damage to their liver, kidneys, or spleen, or changes in their blood.
1,2-Dichloroethane
5 ppb
-
5 ppb
0
Discharge from industrial chemical factories
Some people who drink water containing 1,2-dichloroethane in excess of the MCL over many years may have an increased risk of getting cancer.
1,1-Dichloroethylene
7 ppb
-
7 ppb
7 ppb
Discharge from industrial chemical factories
Some people who drink water containing 1,1-dichloroethylene in excess of the MCL over many years could experience problems with their liver.
cis-1,2-Dichloroethylene
70 ppb
-
70 ppb
70 ppb
Discharge from industrial chemical factories
Some people who drink water containing cis-1,2-dichloroethylene in excess of the MCL over many years could experience problems with their liver.
trans-1,2-Dichloroethylene
100 ppb
-
100 ppb
100 ppb
Discharge from industrial chemical factories
Some people who drink water containing trans-1,2-dichloroethylene well in excess of the MCL over many years could experience problems with their liver.
Dichloromethane
5 ppb
-
5 ppb
0
Discharge from pharmaceutical and chemical factories
Some people who drink water containing dichloromethane in excess of the MCL over many years could have liver problems and may have an increased risk of getting cancer.
1,2-Dichloropropane
5 ppb
-
5 ppb
0
Discharge from industrial chemical factories
Some people who drink water containing 1,2-dichloropropane in excess of the MCL over many years may have an increased risk of getting cancer.
Ethylbenzene
700 ppb
-
700 ppb
700 ppb
Discharge from petroleum refineries
Some people who drink water containing ethylbenzene well in excess of the MCL over many years could experience problems with their liver or kidneys.
Styrene
100 ppb
-
100 ppb
100 ppb
Discharge from rubber and plastic factories; Leaching from landfills
Some people who drink water containing styrene well in excess of the MCL over many years could have problems with their liver, kidneys, or circulatory system.
Tetrachloroethylene
5 ppb
-
5 ppb
0
Discharge from factories and dry cleaners
Some people who drink water containing tetrachloroethylene in excess of the MCL over many years could have problems with their liver, and may have an increased risk of getting cancer.
1,2,4-Trichlorobenzene
70 ppb
-
70 ppb
70 ppb
Discharge from textile-finishing factories
Some people who drink water containing 1,2,4-trichlorobenzene well in excess of the MCL over many years could experience changes in their adrenal glands.
1,1,1-Trichloroethane
200 ppb
-
200 ppb
200 ppb
Discharge from metal degreasing sites and other factories
Some people who drink water containing 1,1,1-trichloroethane in excess of the MCL over many years could experience problems with their liver, nervous system, or circulatory system.
1,1,2-Trichloroethane
5 ppb
-
5 ppb
3 ppb
Discharge from industrial chemical factories
Some people who drink water containing 1,1,2-trichloroethane well in excess of the MCL over many years could have problems with their liver, kidneys, or immune systems.
Toluene
1000 ppm
-
1000 ppm
1000 ppm
Discharge from petroleum factories
Some people who drink water containing toluene well in excess of the MCL over many years could have problems with their nervous system, kidneys, or liver.
Vinyl Chloride
2 ppb
-
2 ppb
0
Leaching from PVC piping: Discharge from plastics factories
Some people who drink water containing vinyl chloride in excess of the MCL over many years may have an increased risk of getting cancer.
Xylenes
10,000 ppb
-
10,000 ppb
10,000 ppb
Discharge from petroleum factories; Discharge from chemical factories
Some people who drink water containing xylenes in excess of the MCL over many years could experience damage to their nervous system.
Treatment Technique Violations
Acrylamide
TT
-
TT
0
Added to water during sewage/ wastewater treatment
Some people who drink water containing high levels of acrylamide over a long period of time could have problems with their nervous system or blood, and may have an increased risk of getting cancer.
Epichlorohydrin
TT
-
TT
0
Discharge from industrial chemical factories; an impurity of some water treatment chemicals
Some people who drink water containing high levels of epichlorohydrin over a long period of time could experience stomach problems, and may have an increased risk of getting cancer.
Groundwater rule TT violations
TT
-
TT
N/A
-
Inadequately treated or inadequately protected water may contain disease-causing organisms. These organisms can cause symptoms such as diarrhea, nausea, cramps, and associated headaches.
Key
 
AL = Action Level
 
MCL = Maximum Contaminant Level
 
MCLG = Maximum Contaminant Level Goal
 
MFL = million fibers per liter
 
MRDL = Maximum Residual Disinfectant Level
 
MRDLG = Maximum Residual Disinfectant Level Goal
 
mrem/year = millirems per year (a measure of radiation absorbed by the body)
 
N/A = Not Applicable
 
NTU = Nephelometric Turbidity Units (a measure of water clarity)
 
pCi/L = picocuries per liter (a measure of radioactivity)
 
ppm = parts per million, or milligrams per liter (mg/L)
 
ppb = parts per billion, or micrograms per liter (ug/L)
 
ppt = parts per trillion, or nanograms per liter (ng/L)
 
ppq = parts per quadrillion, or picograms per liter (pg/L)
 
SAL = state action level
 
TT = Treatment Technique
 
RDS-7086.1
AMENDATORY SECTION(Amending WSR 25-13-093, filed 6/17/25, effective 7/18/25)
WAC 246-290-310Maximum contaminant levels (MCLs) and maximum residual disinfectant levels (MRDLs).
(1) General.
(a) The purveyor shall be responsible for complying with the standards of water quality identified in this section. If a contaminant exceeds its MCL or its maximum residual disinfectant level (MRDL), the purveyor shall take follow-up action under WAC 246-290-320.
(b) When enforcing the standards described under this section, the department shall enforce compliance with the primary standards as its first priority.
(2) Bacteriological.
(a) An E. coli MCL under this subsection is considered a primary standard.
(b) E. coli MCL. An E. coli MCL violation occurs each month in which a system is required to monitor for total coliforms when there is:
(i) E. coli presence in a repeat sample following a total coliform presence routine sample;
(ii) Total coliform presence in any repeat samples collected as a follow-up to a sample with E. coli presence;
(iii) The system fails to take all required repeat samples following an E. coli presence routine sample; or
(iv) The system fails to test for E. coli when any repeat samples test positive for total coliform.
(3) Inorganic chemical and physical.
(a) The primary and secondary standards are listed in Tables 5 and 6 of this section:
TABLE 5
INORGANIC CHEMICAL CHARACTERISTICS
 
Contaminant
Primary
MCLs (mg/L)
 
Antimony (Sb)
 
0.006
 
Arsenic (As)
 
0.010*
 
Asbestos
 
7 million fibers/liter
(longer than 10
microns)
 
Barium (Ba)
 
2.0
 
Beryllium (Be)
 
0.004
 
Cadmium (Cd)
 
0.005
 
Chromium (Cr)
 
0.1
 
Copper (Cu)
 
**
 
Cyanide (CN)
 
0.2
 
Fluoride (F)
 
4.0***
 
Lead (Pb)
 
**
 
Mercury (Hg)
 
0.002
 
Nitrate (as N)
 
10.0
 
Nitrite (as N)
 
1.0
 
Selenium (Se)
 
0.05
 
Sodium (Na)
 
**
 
Thallium (Tl)
 
0.002
 
Contaminant
Secondary MCLs (mg/L)
 
Chloride (Cl)
 
250.0
 
Fluoride (F)
 
2.0***
 
Iron (Fe)
 
0.3
 
Manganese (Mn)
 
0.05
 
Silver (Ag)
 
0.1
 
Sulfate (SO4)
 
250.0
 
Zinc (Zn)
 
5.0
Note*
Does not apply to TNC systems.
Note**
Although the state board of health has not established MCLs for copper, lead, and sodium, there is sufficient public health significance connected with copper, lead, and sodium levels to require inclusion in inorganic chemical and physical source monitoring. For lead and copper, the EPA has established distribution system related levels at which a system is required to consider corrosion control. These levels, called "action levels," are ((0.015))0.0105 mg/L for lead and 1.3 mg/L for copper and are applied to the highest concentration in 10 percent of all samples collected from the distribution system. The EPA has also established a recommended level of 20 mg/L for sodium as a level of concern for those consumers that may be restricted for daily sodium intake in their diets.
Note***
If a water system provides community fluoridation, the level of fluoride and associated requirements are set under WAC 246-290-460.
TABLE 6
PHYSICAL CHARACTERISTICS
Contaminant
Secondary MCLs
Color
15 Color Units
Specific Conductivity
700 umhos/cm
Total Dissolved Solids (TDS)
500 mg/L
(b) Compliance with the MCLs, except for nitrate and nitrite, in this subsection is determined by a running annual average at each sampling point. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling and at least one sampling point is in violation of the MCL. If one sampling point is in violation of the MCL, the system is in violation of the MCL.
(i) If any sample will cause the running annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately.
(ii) If a system fails to collect the required number of samples, compliance will be based on the total number of samples collected.
(iii) If a sample result is less than the detection limit, zero will be used to calculate the running annual average.
(c) Compliance with the MCLs for nitrate and nitrite is determined based on one sample if the levels of these contaminants are below the MCLs as determined under Table 5 of this section. If the levels of nitrate or nitrite exceed the MCLs in the initial sample, a confirmation sample is required under 40 C.F.R. 141.23 (f)(2), and compliance shall be determined based on the average of the initial and confirmation samples.
(4) Disinfection byproducts.
(a) The department shall consider standards under this subsection as primary standards. The MCLs in this subsection apply to monitoring required by WAC 246-290-300(6) and 40 C.F.R. 141.620 - 629.
(b) The MCLs for disinfection byproducts are as follows:
TABLE 7
DISINFECTION BYPRODUCTS
Disinfection Byproduct
MCL (mg/L)
Total Trihalomethanes (TTHMs)
 
0.080
Haloacetic acids (five) (HAA5)
 
0.060
Bromate
 
0.010
Chlorite
 
1.0
(c) Whether a system has exceeded the disinfection byproduct MCLs shall be determined in accordance with 40 C.F.R. 141.133. Beginning on the dates specified for compliance in 40 C.F.R. 141.620(c), compliance with the TTHMs and HAA5 MCLs shall be based on the LRAAs as required by 40 C.F.R. 141.64 (b)(2) and 40 C.F.R. 141.620(d). Compliance with the bromate and chlorite MCL will continue to be determined in accordance with 40 C.F.R. 141.133.
(5) Disinfectant residuals.
(a) The department shall consider standards under this subsection primary standards. The MRDLs in this subsection apply to monitoring required by WAC 246-290-300(6).
(b) The MRDL for disinfectants is as follows:
TABLE 8
DISINFECTANT RESIDUAL MRDLs
Disinfectant Residual
MRDL (mg/L)
Chlorine
 
4.0 (as C12)
Chloramines
 
4.0 (as C12)
Chlorine Dioxide
 
0.8 (as C1O2)
(c) Whether a system has exceeded MRDLs shall be determined in accordance with 40 C.F.R. 141.133.
(6) Radionuclides.
(a) The department shall consider standards under this subsection primary standards.
(b) The MCLs for radium-226 and radium-228, gross alpha particle activity, beta particle and photon radioactivity, and uranium shall be as listed in 40 C.F.R. 141.66.
(7) Organic chemicals.
(a) The department shall consider standards under this subsection primary standards.
(b) VOCs.
(i) The MCLs for VOCs are as follows:
Contaminant
Chemical Abstract Service
(CAS) Number
MCL (ppb)
Vinyl chloride
75-01-4
2
Benzene
71-43-2
5
Carbon tetrachloride
56-23-5
5
1,2-Dichloroethane
107-06-2
5
Trichloroethylene
79-01-6
5
para-Dichlorobenzene
106-46-7
75
1,1-Dichloroethylene
75-35-4
7
1,1,1-Trichloroethane
71-55-6
200
cis-1,2-Dichloroethylene
156-59-2
70
1,2-Dichloropropane
78-87-5
5
Ethylbenzene
100-41-4
700
Monochlorobenzene
108-90-7
100
o-Dichlorobenzene
95-50-1
600
Styrene
100-42-5
100
Trichloroethane
127-18-4
5
Toluene
108-88-3
1,000
trans-1,2-Dichloroethylene
156-60-5
100
Xylenes (total)
1330-20-7
10,000
Dichloromethane
75-09-2
5
1,2,4-Trichlorobenzene
120-82-1
70
1,1,2-Trichloroethane
79-00-5
5
(ii) The department shall determine compliance with this subsection based on compliance with 40 C.F.R. 141.24(f).
(c) SOCs, except PFAS.
(i) MCLs for SOCs shall be as listed in 40 C.F.R. 141.61(c).
(ii) The department shall determine compliance with this subsection based on compliance with 40 C.F.R. 141.24(h).
(d) PFAS.
(i) The MCLs for PFAS, effective in accordance with 40 C.F.R. 141.6, are as follows:
Contaminant
Chemical Abstract Service
(CAS) Number
MCL (ppt or ng/L)
HBWC (ppt or ng/L) for hazard index calculation
PFOA
45285-51-6
4.0
Not applicable
PFOS
45298-90-6
4.0
Not applicable
PFHxS
108427-53-8
10
10
HFPO-DA
122499-17-6
10
10
PFNA
72007-68-2
10
10
PFBS
45187-15-3
No individual MCL
2,000
Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA)
Not applicable
1 (unitless)1
Not applicable
1
The PFAS Mixture Hazard Index (HI) is the sum of component hazard quotients (HQs), which are calculated by dividing the measured component PFAS concentration in water by the relevant health-based water concentration when expressed in the same units (shown in ppt for simplification). The HBWC for PFHxS is 10 ng/l; the HBWC for HFPO-DA is 10 ng/l; the HBWC for PFNA is 10 ng/l; and the HBWC for PFBS is 2000 ng/l.
(ii) The MCLs for PFAS will become effective according to the dates outlined in 40 C.F.R. 141.6.
(8) Other contaminants.
The state board of health shall determine state MCLs for any additional contaminants as described in WAC 246-290-315 (5) through (8).