Key Federal Laws

Safe Drinking Water Act (SDWA)

The Safe Drinking Water Act (SDWA) was established by Congress in 1974 to protect human health from contaminants in drinking water, and to prevent contamination of existing groundwater supplies. The SDWA was extensively amended in 1986 and also in 1996.

Drinking water standards:

A primary focus of the SDWA is on setting national contaminant-based drinking water standards, including both primary and secondary standards. Primary drinking water standards are intended to address adverse health effects, and consist of maximum contaminant level goals (MCLGs), which are non-enforceable goals, and maximum contaminant levels (MCLs), which are enforceable limits set as close to MCLGs as possible, considering cost and feasibility of attainment. Secondary drinking water standards address general public welfare, such as the odor or appearance of drinking water, and are also non-enforceable.  The National Primary Drinking Water Regulations appear at 40 CFR Part 141.

"Contaminant" is defined by the SDWA  to include any physical, chemical, biological, or radiological substance.  Currently regulated contaminants include bacteriological contaminants, turbidity, fluorides, certain pesticides, and certain heavy metals.  Under the 1996 Amendments, EPA must identify a list of possible additional contaminants to regulate, based on the likelihood of their occurrence in public drinking water systems, and must evaluate at least 5 contaminants every 5 years for possible regulation.

Under the SDWA, only public water systems are subject to the drinking water standards..  A "public water system" is one that provides piped water for human consumption and has at least 15 service connections or regularly serves at least 25 persons.  Regulations require these systems to meet MCLs and/or to use certain treatment techniques to protect against adverse health effects.  Regulations include prescribed testing, record keeping (for example, at least 5 years for bacteriological sampling results and at least 10 years for chemical sampling results), reporting, and timely notification of failure to meet applicable drinking water standards.

Underground Injection Control

The Underground Injection Control Program is designed to protect usable aquifers from contaminations migrating from injection wells.  The Program requires a permit before the placement of fluids into a bored, drilled, driven, or dug well (excluding surface lagoons).  Regulations governing the Underground Injection Control (UIC) Program of the SDWA are contained in 40 CFR Part 144-148. The UIC program establishes permit conditions - including design, operating, inspection, and monitoring requirements - for five classes of underground injection wells:
  • Class I wells are used to inject hazardous waste beneath the lowest formation containing a underground source of drinking water within one-quarter mile of the well bore.
  • Class II wells are used for oil and natural gas recovery.
  • Class III wells are used for mineral extraction.
  • Class IV wells (now prohibited under RCRA) are used to inject hazardous waste into or above a formation that contains an underground source of drinking water within one-quarter mile of the well bore, or any other wells used to dispose of hazardous waste.
  • Class V wells are all wells other than Classes I-IV.
Injection wells that manage hazardous wastes must also meet RCRA land disposal restrictions standards.

SDWA intended that UIC management be handled by states, and most states have received delegated authority to manage Federal UIC program requirements.  However, in a few cases where states have not demonstrated an ability to manage the program, the EPA will administer it in lieu of the state.

Standards for remediation

Maximum Contaminant Levels established under the SDWA attain additional importance due to their frequent incorporation into site cleanup programs, such as Superfund. Specifically, SDWA Maximum Contaminant Levels can be used to establish site cleanup criteria if they are identified as Applicable or Relevant and Appropriate Requirements (ARARs), through the process established by CERCLA, and detailed in 40 CFR 300.400(g).

Other provisions

The SDWA also provides for a Federally-implemented Sole Source Aquifer program. This program prohibits Federal funds from being expended on projects that may contaminate the sole or principal source of drinking water for a given area. In addition, the SDWA provides for a State-implemented Wellhead Protection program, designed to protect drinking water wells and drinking water recharge areas.

EPA’s Safe Drinking Water Hotline, at (800) 426-4791, answers questions and distributes guidance pertaining to SDWA standards. The Hotline operates from 9:00 a.m. to 5:30 p.m. ET, excluding Federal holidays.

Program office links:
Office of Air and Radiation
Office of Ground Water and Drinking Water

40 CFR 141 National Primary Drinking Water Regulations
40 CFR 144, 145, 146, 147, and 148  Underground Injection Control (UIC)
40 CFR 300.400(g)  ARAR process under CERCLA

Related sites:
EPA Plain English Guide to the Clean Air Act
Details on 1996 Amendments


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