These handy little bottles are designed with a built in filter. The filter uses three different types of technology which makes us feel pretty safe drinking the tap water wherever our travels take us. We’re always happy to recommend them because they have been a brilliant investment for our trip. Water-to-Go saves plastic and saves money. So far, we have used them to drink the tap water in Nepal, India, Sri Lanka, Thailand and Cambodia. We even filled them from streams and waterfalls while we were trekking in the Himalayas. They are easy to use, and we carry them everywhere.