The Steripen does have it's downfalls...the battery did last a long time, but it would be something you'd have to check on periodically for a BOB. I was using mine while backpacking through Venezuela, and most water sources were terribly contaminated. The Steripen didn't help with the taste of the water. I ended up using a pump filter first and then the Steripen if the water source wasn't clear and moving. A pump filter, boiling, or tablets aren't going to remove or kill all of the parasites, viruses, bacteria, etc. that will be present in heavily contaminated water, so I liked the claims made by the Steri-pen makers. Bye-bye flukes and giardia lambia.