Phone, keys, wallet, and water bottle. For some people, leaving home without their bottle feels almost like forgetting something essential. They carry it to work, the gym, shopping trips, airports and even restaurants where water is readily available. The obvious explanation is hydration, but psychology suggests the behavior can acquire additional functions. A personal bottle can become part of a context-dependent habit, increase perceived behavioral control, reinforce a person's self-identity and remove a small uncertainty from the day. Research on refillable-bottle use supports some of these possibilities: attitudes, perceived behavioral control, previous behavior and self-identity have all been linked with people's intentions or actual use of reusable bottles.
