I was skeptical at first. My wife more so than me. We have now used a Water-to-Go bottle each daily for 3 months, filling up from taps everywhere in China, Vietnam, Bali, Philippines and no upset tummy so far touch wood. I no longer have to think “is water safe to drink in this country?” The bottle and replacement filters have easily paid for themselves from us not needing to buy plastic water bottles even if they are super cheap. Next stop, India!