Background on Drinking Water Standards in the Safe Drinking Water Act (SDWA)

Summary of SDWA Related to Drinking Water Contaminants:

• The United States Congress enacted the Safe Drinking Water Act (SDWA) in 1974, later amending and reauthorizing it in 1986 and 1996.
  • Is the primary federal law that ensures the quality of America's drinking water.
  • Authorizes EPA to set national standards for drinking water to protect against health effects from exposure to naturally-occurring and man-made contaminants.
• EPA works with states, localities, and water suppliers who carry out these standards.
• Drinking water standards only apply to public water systems (not individual private wells).

Drinking Water Standards Apply to Public Water Systems:

• Public water systems (PWSs) are those having at least 15 service connections or serving at least 25 people for 60 or more days a year.
• There are more than 150,000 public water systems across the U.S. serving over 300 million people.

Three Types of Public Water Systems: 

• Community Water Systems (CWSs)
  • ​Provide water to the same population year-round (e.g., homes and apartment buildings).
  • Includes approximately 52,000 systems serving the majority of the U.S. population.
• Non-Transient Non-Community Water Systems (NTNCWSs)
  • ​Provide water to same people at least six months a year, but not all year (e.g., schools, factories, churches, office buildings that have their own water system).
  • Includes approximately 85,000 systems.
• Transient Non-Community Water System (TNCWS)
  • ​Provide water where people do not remain for long periods of time (e.g., gas stations, campgrounds).
  • Includes approximately 18,000 systems.

SDWA Processes Involving Drinking Water Contaminants:

• Contaminant Candidate List (CCL)
  • Requires EPA to develop a list of unregulated contaminants that are known or may occur in drinking water.
  • Published every five years.
• Regulatory Determination for CCL
  • Requires EPA to decide whether to regulate at least five CCL contaminants with a drinking water standard every five years.
  • Specifies three criteria (adverse health effects, occurrence in public water systems, meaningful opportunity for health risk reduction).
• Unregulated Contaminant Monitoring
  • Requires EPA to establish criteria for a program to monitor at least 30 unregulated contaminants every five years.
• Regulation Development
  • If EPA decides to regulate a contaminant via the regulatory determination process, the agency has 24 months from the time of the determination to propose a regulation and 18 months from the proposal to finalize the regulation.
  • The SDWA requires evaluation of a number of factors in the standard setting process.
• Six Year Review
  • Requires EPA to review each standard every six years and, if appropriate, revise the standard.
  • Any revision must maintain or improve public health protection.
  • If a standard is revised, EPA goes through the standard setting process again and evaluates a number of factors.
• National Contaminant Occurrence Database (NCOD)
  • Requires EPA to assemble and maintain a national drinking water contaminant occurrence database using information for both regulated and unregulated contaminants in public water systems.

For more information on broader provisions of SDWA, select the Safe Drinking Water Act website.