“For our trek, the SteriPEN worked just fine. On Kilimanjaro, the water source is mountain streams, so we filtered the water, poured it into a 16 oz. Nalgene bottle and applied the SteriPEN treatment to it. We repeated this until all of our water bottles, camelbacks, etc. were full for the next day. We also did this in Nepal. One of the things that I like best about the SteriPEN is that it means one can walk into a hotel room in a 3rd world country and immediately sterilize the water from the lavatory faucet rather than having to go find a source of bottled water. Another problem is that the water sold as mineral water in bottles in some countries is not to be trusted. We have been back a few days and unfortunately, have spent part of them preparing a “safe” room in the house plus loading the car with supplies in case we need to evacuate by road. BUT, the water filter and SteriPEN are in our exit supplies, and it makes me feel better knowing that I can have clean water. I am also thrilled to have the solar powered battery charger at this time because as long as there is sun, we can charge batteries for flashlights, the GPS, etc. Hope this info helps you, and I hope you sell lots of SteriPENs. It is a great product. Hope to meet you some day.