Fits Carry-On Packing

Space in a carry-on is measured in inches, and liquids are restricted.

Handles Unfamiliar Taps

Hotel plumbing and local treatment vary far more than labels suggest.

Taste and Odor Reduction

Heavy chlorine is safe but unpleasant enough that people stop drinking.

Fast Refill at a Sink

Refills happen in a bathroom between a checkout and a departure.

Bottle-Integrated Filter

One item to carry beats a bottle plus a separate filter in a daypack.