(Problem below) I recently went to Peru on a study abroad trip and this gave me confidence when drinking water. (I also now use it on US water. It is scary what is still in the water we drink in the US and this may not help much with our problems, but it makes me feel better :/ ) I took Typhoid pills to avoid any food-related problems, but having this for drinking water, tooth brush water, or even a little water to wash your face, is key. I absolutely loved it and, as I was on a trip of almost 30 students where almost all of them had a SteriPen of almost all the different makes and sizes, I really love this specific style (Ultra). The super small one I remember was hard to put in some containers and because the light could only penetrate so deep, they didn't feel as secure as I did.

***The only problem I did have was it not working occasionally. It's strange, but sometimes I would try to purify water (by the rules) several times, and it would never work. I had to borrow other people's SteriPens, because I thought mine was broke! Another student with the same model (Ultra) found that hers did the same and that the only way to make it work was to run it under cold water, then put it back in the glass/cup/bottle. Quite annoying*** ALL OTHER MODELS OF THE STERIPEN WORKED PERFECTLY!

I chose this (after doing thorough research on all the models), because I liked that it was USB run and didn't need batteries which frankly causes a lot of waste in our world. However, it's inability to always work is a serious problem. I don't want to scare people from running away from this make and certainly not the SteriPen in general, but its good to know. Also, NO other make or model of the SteriPen had ANY problems. The only issue I had is isolated to the Ultra model. ALL OTHER MODELS WORK PERFECTLY!!!

I bought this for a backpacking trip this past weekend as a replacement for my Sawyer Mini which has served me well but is a little bit of a pain to use. I give this three stars because the device is GREAT when it works. My issue and it seems I am not alone with this, is that the UV light frequently does not come on resulting in a frown on the pen. I would have to power cycle this multiple times and then suddenly it would work. For a device that I depend on for staying alive in the back country that is not at all acceptable. Always carry a backup, but in this case our backup would become primary and then .. no other backup.

Just completed my 12-day EBC trek! This is the best time to give my experience on battery life as well as if it really works. It absolutely works! Had no stomach problems, digestion was good for the entire duration and good bowel movements. I used it to sterilise the tap water (as well as spring water) at all my stops (Monjo, Namche, Phortse, Dhugla, Lobuche) except for Dingboche when I was "tricked" to purchase bottled water, because I think the guide realised how much I was saving on water and hydrating properly while gaining altitude.

I did a full charge at my first stop and did not need to recharge for the next 11 days. Awesome! Kept it warm in my sleeping bag at night and morning routines are treating in a water bottle before transferring to a water bag. (Also followed diligently others advice on drying the bottle threads to avoid any cross contamination.) Was able to enjoy the water taste without any chemicals.

Overall 100% satisfied with this product (worked as advertised). It is the second best equipment I purchased for my trek and looking forward to using it for future trips.

This is a brilliant device as an alternative to pumping, chemically treating, or boiling water in the backcountry. My negative rating comes as a result of issues I had making contact with the SteriPen customer support representatives when a problem arose. On three of the most inopportune occasions (once in Nepal, twice in the Montana Rockies), my SteriPEN refused to treat stream water and instead gave me the "bad or damaged bulb" signal. By the time I returned home, the unit would inexplicably begin functioning again. Over the past 10 days prior to this writing, I tried to contact SteriPEN three times by phone, each time getting a recording saying all representatives were helping other customers and that they would call me back. I also tried twice by email, each time receiving a computer-generated response saying I would receive an email reply within 48 hours. All five attempts resulted in no call back or email reply from SteriPEN. I had registered my device with SteriPEN shortly after my purchase so the unresponsiveness could not have been as a result of my failure to follow their registration instructions. However appealing the SteriPEN is as a means of making stream water suitable for consumption, this product is a waste of money if the manufacturer fails to back up its assurances that their product will work.

I live in Naples Florida and due to hurricane Irma we have had no power, water has been on and off and when water is on we are under a boil water advisory. You can't boil barer if you have no power and your stove is electric. The SteriPEN has been a life saver! The ability to take possibly contaminated tap water and have bacteria, viruses and Protozoa killed in 48 seconds is amazing. Bottled water and gas have been depleted in Naples Florida for days, having the ability to make safe water for my family has been a life saver!