Are refill stations common enough to just bring a reusable bottle?

Yes — airports, train stations, gyms, malls, museums, and city parks all have refill stations or fountains. Tap water is safe in the US, Canada, UK, Australia, most of Europe, and Japan. A reusable bottle is cheaper, better for the environment, and you’ll never be stuck. Just bring a filter bottle for remote areas or places with questionable tap water.