The Environmental Protection Agency rules set out how frequently airlines must flush and disinfect the water systems on planes and test for coliform bacteria, which are associated with disease-causing germs. The rules apply to water supplied through aircraft water systems, not bottled water.
EPA determined five years ago that airlines weren't complying with drinking water regulations. The agency tested water from 327 planes, of which 15 percent tested positive for coliform. The EPA estimates the cost of the new rules at $7 million a year, or about a penny per ticket.