Pieter --

This topic sparked some interesting discussion last September around the time TSA revised its rules; two threads on the issue are here and here .

While the TSA regulations do allow an exception to the "3 ounces" limit for "liquids including water, juice, or liquid nutrition or gels for passengers with a disability or medical condition," I expect that such exceptions are granted, or not, depending on how the TSA security person on duty is feeling that day, and I do not know what is required in terms of "proving" that need. Amy's suggestion above seems like a reasonable way of handling the problem; in addition, bottled water is now sold in areas past the security screening.

When I flew home from China recently, the Beijing airport was just implementing, for international flights, the US screening rules for liquids and gels. The screener took away my under-3-ounces Purell hand sanitizer (even though I had brought it with me with no problem), saying it could be used to start a fire(!).

-- Leslie