Coffee, tea, or bacteria? (Health/Bacteria).

Next time you fly, think twice before brushing your teeth or washing your hands in the plane's lavatory. Tap water on planes may be swimming with bacteria (microscopic single-cell organisms), claims a recent Wall Street Journal investigation: "Contamination was the rule, not the exception," sleuthing reporters concluded.

What inspired their investigation? Last March, 13-year-old Zach Bjornson-Hooper of Alamo, California, brought water-testing kits on a family trip to Australia and New Zealand--as part of a science project. In tapwater samples from his flights, Zach found a horde of bacteria. "It was really gross," he says.

His tests turned up thousands of bacteria per milliliter of plane tap water, and when Journal reporters spied Zach's report on a Web site, they hopped on planes to test the water themselves. Then they turned over samples to biologists for lab tests, which turned up millions of gross bacteria per milliliter of airplane tap water! "This water isn't drinkable by any means," says Donald Hendrickson, director of Hoosier Microbiology Laboratories in Muncie, Indiana.

Luckily, airlines offer bottled drinking water. Safe drinking water should contain no more than 500 colony-forming units (cfu) of bacteria per milliliter, says the U.S. Environmental Protection Agency (EPA). One cfu is a single bacterial cell, or bacterium. But a single cell can multiply into 100 million in just one to two days, says University of South Florida biologist Joan Rose.

IT'S A DIRTY WORLD

Run your tongue over your teeth and you're licking thousands of microscopic germs. Your body and most surfaces you touch--desks, faucets, pencils--ooze with invisible critters (see bar graph, above). "Bacteria is everywhere, but 99 percent of it is harmless," says germ expert Chuck Gerber at the University of Arizona. "We're only concerned about pathogenic bacteria, those which cause disease."

Although most of the bacteria uncovered in airplane tap water weren't pathogenic, the tests did turn up some nasty bugs. Two examples: Pseudomonas, which can cause skin and respiratory infections; and Citrobacter, a coliform or fecal bacteria, which can induce diarrhea and fever. The EPA allows zero coliform bacteria in public drinking water.

Now federal officials say they're working to clean up airlines' water tanks, trucks, and hoses. That's good news for frequent fliers like Zach. But he's not taking any chances: "I only drink bottled water, either water I've bought before I fly or water the flight attendants promise me is pure bottled."

GERMS BY
THE NUMBER

Various kinds of germs
lurk on every square
inch of common
school surfaces. How
many times more
germs are on a cafeteria
cutting board compared
to a toilet seat?

                  NUMBER OF GERMS
TYPE OF SURFACE   PER SQUARE INCH

Kitchen faucet            229,000

Cutting board              62,000

Office phone               25,127

Desktop                    20,961

Keyboard                    3,295

PC mouse                    1,676

Fax machine                   301

Toilet seat                    49

Note: Table made from bar graph.

SOURCE: CHUCK GERBER, UNIVERSITY OF ARIZONA