A reusable water bottle is a green investment that can pay off both ecologically and economically. But like any food service item, it needs to be cleaned and maintained to keep it free from harmful bacteria. Once in a while, add some white vinegar and a cup of hot water to your reusable water bottle. Let it sit for at least 15 minutes (or longer if you can) -- the acid in the white vinegar will kill bacteria and odor. Use a scrubbing brush to clean the inside of the bottle. Rinse with more water and allow it to dry thoroughly. When not in use, store clean bottles in the refrigerator; the cool temperature prevents the growth of bacteria inside the water bottle.