(CBS 58) – A new study ranks the safety of the on-board water of several U.S. airlines.

This is water used in coffee, tea and the bathrooms.

According to USA Today, the study based rankings on water test violations, positive E. coli water sample reports and the airline’s willingness to answer water-quality questions.

The study says a score of 3.0 or better indicates the airline has relatively, safe and clean water.

• 1. Alaska Airlines: 3.3
• 2. Allegiant Air: 3.3
• 3. Hawaiian Airlines: 3.1
• 4. Frontier Airlines: 2.6
• 5. Southwest Airlines: 2.4
• 6. Delta Air Lines: 1.6
• 7. American Airlines: 1.5
• 8. United Airlines: 1.2
• 9. JetBlue: 1
• 10. Spirit Airlines: 1

Experts recommended passengers don’t drink coffee or tea on-board and instead of washing their hands in the bathroom, just bring hand-sanitizer.

The study also looked at regional airlines. Air Wisconsin Airlines which operates as United Express, received a score 0.67.