We use the steri pen. For many years, I used iodine, or occasionally bought water. In comparison, the steri-pen has been a miracle worker. 

It was the most help to us in Nepal, where all the water had to be treated, but was quite clear to start with. We did a 2 week trek to Everest Base Camp using the steri-pen to treat every drop of the water we drank, and never got sick. The pen is small and really lightweight (2 oz), so we didn't mind carrying it. It sterilizes 1/2 liter in 45 seconds or 1 liter in 1 1/2 minutes, so it was fast. And the only thing required to keep it going is batteries - no filters to change. We were able to do all our own water as well as water for other travelers. 

When we got home, we used it in the Colorado Rockies. Getting to drink cold mountain water minutes after we collected it was amazing. 

Just be sure you'll be able to get relatively clear water. If the water is too muddy, the light won't be effective.