A new analysis ranks U.S. states on tap water quality, using data from the Environmental Protection Agency and the Environmental Working Group.

Researchers evaluated regulatory compliance, oversight, and contaminant levels for public water systems. Approximately 10% of Americans on private wells were excluded.

The top ten states for the cleanest tap water are:

  1. South Carolina
  2. Hawaii
  3. Minnesota
  4. North Dakota
  5. Maryland
  6. Alabama
  7. Michigan
  8. Wisconsin
  9. South Dakota
  10. New Hampshire

All states provide technically safe drinking water under federal monitoring. Lower-ranked states may have more violations or higher contaminant levels.

The ten states with the lowest rankings are:

  1. North Carolina
  2. Nevada
  3. Wyoming
  4. West Virginia
  5. Delaware
  6. Ohio
  7. New York
  8. Texas
  9. Alaska
  10. Louisiana & Oklahoma (tied)

Experts note water filters are not always necessary but can improve taste. Common types include pitcher, faucet-attached, and reverse osmosis systems.