Water Quality and the Safe Drinking Water Act: What You Need to Know

The Foundation: The Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) of 1974 is the federal law that protects public drinking water supplies throughout the United States. The EPA sets national standards called Maximum Contaminant Levels (MCLs) for over 90 contaminants, and states are responsible for enforcing these standards.

How Tap Water is Treated

Most municipal water systems use a multi-step treatment process:

  • Coagulation and flocculation: Chemicals added to bind particles together
  • Sedimentation: Heavy particles settle to the bottom
  • Filtration: Water passes through sand, gravel, and charcoal filters
  • Disinfection: Chlorine, chloramine, UV, or ozone kills bacteria and viruses
  • pH adjustment and corrosion control: Prevents pipe corrosion

    • Common Drinking Water Contaminants

    Regulated Contaminants

    • Lead: From old pipes and plumbing fixtures (Flint, MI crisis; still a risk in pre-1986 buildings)
    • Nitrates: From agricultural runoff; dangerous for infants
    • Arsenic: Natural geological sources; regulated at 10 ppb
    • PFAS (“forever chemicals”): New EPA limits of 4 parts per trillion for PFOA and PFOS (2024)
    • Coliform bacteria: Indicates potential fecal contamination
    • Disinfection byproducts: Formed when chlorine reacts with organic matter

      • Emerging Concerns

    • Microplastics: Not yet regulated; research ongoing
    • Pharmaceutical residues: Trace amounts from medication disposal
    • Glyphosate (Roundup): Herbicide runoff

      • Your Right to Know: Consumer Confidence Reports

      Every community water system must provide an annual Consumer Confidence Report (CCR) — also called a water quality report — by July 1 each year. Your CCR must include:

    • Source of your drinking water
    • Levels of detected contaminants
    • Compliance with EPA standards
    • Health effects of regulated contaminants

      • Get your CCR: Contact your water utility or search at EPA’s website (epa.gov/ccr).

      Private Wells

      If you have a private well, you are responsible for your own water quality testing. The EPA does not regulate private wells.

      Recommended testing schedule:

    • Coliform bacteria: Every year
    • Nitrates: Every year (especially if near agriculture)
    • pH, hardness, iron: Every 3 years
    • Full panel: Every 5 years, or after flooding/nearby construction

      • Contact your local health department for guidance and low-cost or free testing options.

      Signs of Water Quality Problems

    • Cloudy water: Sediment or air bubbles (usually harmless) or pathogen contamination
    • Yellow/brown water: Rust, iron, or manganese
    • Blue-green stains: Copper from corroding pipes
    • Rotten egg smell: Hydrogen sulfide (natural or sewage)
    • Chlorine taste/smell: Usually safe; can indicate excess treatment chemical
    • Slippery feel: Sodium or softened water

      • What to Do if You’re Concerned

    • Contact your water utility — they must respond to complaints
    • Request a water quality test — utilities must test on request in some circumstances
    • Get your water tested independently — find a certified lab at epa.gov/drinkinwater
    • Use a certified filter — NSF International certifies filters for specific contaminants
    • File a complaint — with your state drinking water program or EPA

      • Filters: What Works for What

      | Filter Type | Removes |
      |—|—|
      | Pitcher (Brita, ZeroWater) | Chlorine, some metals, some PFAS |
      | Under-sink carbon filter | Chlorine, VOCs, some pesticides |
      | Reverse osmosis | Lead, arsenic, nitrates, PFAS, most contaminants |
      | UV filter | Bacteria and viruses |

      Always look for NSF/ANSI certification for the specific contaminant you’re concerned about.

      Resources

    • EPA Drinking Water: epa.gov/drinkingwater
    • EWG Tap Water Database: ewg.org/tapwater (search by zip code)
    • NSF Certified Products: nsf.org
    • EPA Safe Drinking Water Hotline: 1-800-426-4791