The Safe Drinking Water Act (SDWA) is the primary federal law in the United States intended to ensure safe drinking water for the public.United States. Safe Drinking Water Act. ; ; et seq. 1974-12-16. Pursuant to the act, the Environmental Protection Agency (EPA) is required to set standards for drinking water quality and oversee all states, localities, and water suppliers that implement the standards.

The SDWA applies to every public water system (PWS) in the United States.A public water system has at least 15 service connections or regularly serves at least 25 individuals, at least 60 days per year. There are currently over 148,000 public water systems providing water to almost all Americans at some time in their lives. The Act does not cover private wells (in 2020, 13% of US households were served by private wells).

The SDWA does not apply to bottled water. Bottled water is regulated by the Food and Drug Administration (FDA), under the Federal Food, Drug, and Cosmetic Act.United States. Federal Food, Drug, and Cosmetic Act, et seq.

National Primary Drinking Water Regulations

The SDWA requires EPA to establish National Primary Drinking Water Regulations (NPDWRs) for contaminants that may cause adverse public health effects.EPA. "National Primary Drinking Water Regulations." Code of Federal Regulations, 40 CFR Part 141.

The regulations include both mandatory requirements (Maximum Contaminant Levels, or MCLs; and Treatment Techniques) and nonenforceable health goals (Maximum Contaminant Level Goals, or MCLGs) for each included contaminant. As of 2019 EPA has issued 88 standards for microorganisms, chemicals and radionuclides.

MCLs have additional significance because they can be used under the Superfund law as "Applicable or Relevant and Appropriate Requirements" in cleanups of contaminated sites on the National Priorities List.

For some contaminants, EPA establishes a Treatment Technique (TT) instead of an MCL. TTs are enforceable procedures that drinking water systems must follow in treating their water for a contaminant.

Federal drinking water standards are organized into six groups: Microorganisms Disinfectants Disinfection byproducts Inorganic chemicals Organic chemicals Radionuclides.

Microorganisms EPA has issued standards for Cryptosporidium, Giardia lamblia, Legionella, coliform bacteria and enteric viruses. EPA also requires two microorganism-related tests to indicate water quality: plate count and turbidity. The agency issued its initial Surface Water Treatment Rule in 1989, to address contamination from viruses, bacteria and Giardia lamblia. The most recent amendment is the Long Term 2 Enhanced Surface Water Treatment Rule, promulgated in 2006, requiring public water systems to employ a Treatment Technique to control Cryptosporidium and other pathogens.EPA (2006-01-05). "National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule."

Disinfectants EPA has issued standards for chlorine, monochloramine and chlorine dioxide.

Disinfection by-products EPA has issued standards for bromate, chlorite, haloacetic acids and trihalomethanes.

Inorganic chemicals EPA has issued standards for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, copper, cyanide, fluoride, lead, mercury, nitrate, nitrite, selenium and thallium.

"Lead Free" plumbing requirements

The 1986 amendments require EPA to set standards limiting the concentration of lead in public water systems, and defines "lead free" pipes as: (1) solders and flux containing not more than 0.2 percent lead; (2) pipes and pipe fittings containing not more than 8.0 percent lead; and (3) plumbing fittings and fixtures as defined in industry-developed voluntary standards (issued no later than August 6, 1997), or standards developed by EPA in lieu of voluntary standards.Safe Drinking Water Act. "Prohibition on use of lead pipes, solder, and flux." .

EPA issued an initial lead and copper regulation in 1991.EPA. "Maximum Contaminant Level Goals and National Primary Drinking Water Regulations for Lead and Copper; Final Rule." Federal Register, , 1991-06-07. The regulation specifies a Treatment Technique rather than an MCL.EPA (2007-10-10). "National Primary Drinking Water Regulations for Lead and Copper: Short-Term Regulatory Revisions and Clarifications." Federal Register,

Congress tightened the definition of "lead free" plumbing in a 2011 amendment to the Act. EPA published a final rule implementing the amendment on September 1, 2020.EPA (2020-09-01). "Use of Lead Free Pipes, Fittings, Fixtures, Solder, and Flux for Drinking Water; Final rule." Federal Register,

In response to the Flint, Michigan water crisis, EPA published revisions to the Lead and Copper Rule on January 15, 2021 addressing testing, pipe replacement and related issues. The rule mandates additional requirements for sampling tap water, corrosion control, public outreach and testing water in schools.EPA (2021-01-15). "National Primary Drinking Water Regulations: Lead and Copper Rule Revisions." Final rule. Several citizen and environmental groups immediately filed lawsuits challenging the rule. Following the lawsuit, EPA issued its final "Lead and Copper Rule Improvements" regulation on October 8, 2024, which requires the removal of all lead pipes within ten years. Additionally, the regulation lowers the action level of lead contamination to 10ppb from the current limit of 15ppb.

Organic chemicals EPA has issued standards for over 53 organic compounds, including benzene, dioxin (2,3,7,8-TCDD), PCBs, styrene, toluene, vinyl chloride and several pesticides.

Perfluorinated alkylated substances

In March 2021 EPA announced that it would develop regulations for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). In April 2024 EPA published final standards for PFOA, PFOS, perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (also known as GenX) and perfluorobutanesulfonic acid (PFBS).EPA (2024-04-26). "PFAS National Primary Drinking Water Regulation." Federal Register, The agency is providing grant funds to assist small and disadvantaged communities in testing for and treating PFAS contamination in their water systems.

Radionuclides EPA has issued standards for alpha particles, beta particles and photon emitters, radium and uranium. EPA proposed regulations for radon in 1991 and 1999.

Secondary standards Secondary drinking water standards are non-regulatory guidelines for aesthetic characteristics, including taste, color, and odor.

Health advisories EPA issues "health advisories" for some contaminants; some of which have not been regulated with MCLs. Health advisories provide technical information to public health officials about health effects, methods for chemical analysis, and treatment methods. The advisories are not enforceable. EPA was given explicit authority to issue advisories in the 1996 SDWA amendments.SDWA sec. 1412(b)(1)(F); As of 2022, health advisories have been issued for the following contaminants. +EPA Drinking Water Health Advisories Chemical Contaminants Microbial ContaminantsBoronCyanotoxinsDacthal (DCPA) and Dacthal degradatesCryptosporidium2,4- and 2,6- Dinitrotoluene (DNT)LegionellaFluorideGiardiaGenXMycobacteriaManganeseMethyl tert-butyl ether (MTBE)OxamylPerchloratePerfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) (published 2022)*Perfluorobutanesulfonic acid (PFBS)SodiumSulfate1,1,2,2-Tetrachloroethane* Note: In 2024 EPA stated that its 2022 advisories for PFOA and PFOS were outdated.Updated toxicity assessments were published concurrently with the final 2024 regulation.

State standards The SDWA allows states to set standards which are more stringent than the federal standards, and to issue standards for contaminants that EPA has not regulated. Several states have issued their own standards for a few contaminants, including fluoride,New York State Department of Health, Albany, NY (2018). New York Codes, Rules and Regulations. Title 10, SubPart 5-1 - Public Water Supplies. "Public Water Systems; Maximum Contaminant Levels; Monitoring Requirements; Notification Requirements." Section 5-1.52 - Tables. perchlorate and perfluorinated alkylated substances (PFAS).

Future standards

Unregulated contaminants The SDWA requires EPA to identify and list unregulated contaminants which may require regulation. The Agency must publish this list, called the Contaminant Candidate List (CCL) every five years. EPA is required to decide whether to regulate at least five or more listed contaminants. EPA uses this list to prioritize research and data collection efforts, which support the regulatory determination process.

As of 2024, EPA has developed five CCLs: CCL1: 50 chemical and 10 microbiological contaminants/contaminant groups were listed in 1998.EPA (1998-03-02). "Announcement of the Drinking Water Contaminant Candidate List." Federal Register, In 2003 EPA made a determination that no regulatory action was needed on nine of these contaminants.EPA (2003-07-18). "Announcement of Regulatory Determinations for Priority Contaminants on the Drinking Water Contaminant Candidate List." CCL2: EPA carried forward the remaining 51 contaminants from CCL1 for consideration in 2005.EPA (2005-02-24) "Drinking Water Contaminant Candidate List 2." In 2008 EPA determined that no regulatory action was needed on 11 of these contaminants.EPA (2008-07-30). "Regulatory Determinations Regarding Contaminants on the Second Drinking Water Contaminant Candidate List." . CCL3: EPA revised its listing process, based on recommendations from the National Research Council and the National Drinking Water Advisory Council (a Federal Advisory Committee). It expanded its initial review to 7,500 potential chemical and microbial contaminants, and subsequently narrowed this universe to a list of 600 for further evaluation. 104 chemicals or chemical groups and 12 microbiological contaminants were listed in 2009.EPA (2009-10-08). "Drinking Water Contaminant Candidate List 3-Final." In 2011 EPA announced it would develop regulations for perchlorate, which had been listed beginning with CCL1.EPA (2011-02-11). "Drinking Water: Regulatory Determination on Perchlorate." In 2016 EPA determined that no regulatory action was needed on four other listed contaminants, and delayed determination on a fifth contaminant, in order to review additional data.EPA (2016-01-04). "Announcement of Final Regulatory Determinations for Contaminants on the Third Drinking Water Contaminant Candidate List." . CCL4: EPA carried forward the CCL3 contaminants for which determinations had not been made, and requested public comment on additional contaminants. 97 chemicals or chemical groups and 12 microbial contaminants were listed in 2016.EPA (2016-11-17) "Drinking Water Contaminant Candidate List 4-Final." . In March 2021 EPA announced that it would develop regulations for two of the CCL4 contaminants: PFOA and PFOS.EPA (2021-03-03). "Announcement of Final Regulatory Determinations for Contaminants on the Fourth Drinking Water Contaminant Candidate List." Federal Register, In November 2022 EPA published CCL5. The list includes 66 chemicals, three chemical groups (including PFAS) and 12 microbes.EPA (2022-11-14). "Drinking Water Contaminant Candidate List 5-Final." Federal Register,

EPA requested public comment on its draft of the 6th CCL in 2023.EPA (2023-02-17). "Drinking Water Contaminant Candidate List 6-Nominations." Federal Register,