I have also a steripen and I've had great results with mine. I would recommend a backup as well but I haven't had a failure on mine and it has been overseas with using it several times a day for the full duration of the trip with no sickness. The water does have to be relatively clear and can be filtered. I carried a combi filter to pre filter the water but didn't need it and didn't use it for the whole trip. I would recommend one for sure.