What if you're flying on the red-eye from New York to California and at 5 a.m. West Coast time, and you're desperate for a cuppa Joe before you land? Well, according to a 2026 Airline Water Study from the Center for Food as Medicine & Longevity, you shouldn’t do it.

They ranked the water quality of 10 major and 11 regional airlines, and their latest findings show that only some provide relatively safe, clean water.

Delta, Frontier, and Alaska Airlines were the top three, earning grades of an A, A, and B, respectively. Only one regional airline earned a B (none got As). That was GoJet, operating as a United Express brand of United Airlines.

American Airlines was ranked the worst of the major airlines with a grade of D. And regional airlines were especially guilty of serving contaminated water.

You can see the whole report at foodmedcenter.org.

Even for airlines that get water quality right most of the time, what does the Center recommend to protect yourself from exposure to E. coli and other bacteria?

1. Never drink any water onboard that isn't in a sealed glass bottle or can.

2. Don't drink coffee or tea onboard. (I suggest you bring a stainless steel beverage container with water or coffee with you).

3. Don't wash hands in the bathroom; use alcohol-based hand sanitizer containing at least 60% alcohol.

For more information on how to strengthen your immune system, protect yourself from viral and bacterial infections, and more, check out "YOU: The Owner's Manual revised edition."