Meet our new water purification system… Steri-pen. Is rechargeable with a USB plug. Lasts about 6 days. 90 seconds of UV light zaps all the critters in our water. So far so good.
“It will shine still brighter when night is about you. May it be a light to you in dark places, when all other lights go out.” (First dork who can name this reference in the comments gets a postcard from the trail!)
UPDATE 1/6/16: We used Steri-pen our entire PCT thru hike and never got sick. We found that the charge would last 3.5 days of full-on thru hiker summer water consumption, with two people using it. Eventually we each got our own, so we could have more autonomy, and also so we could extend use between charges. Once I had my own steri-pen I used it for up to 6 days consecutively w/out needing to charge it. My only critique is that it takes a long time to fully charge the steri pen, perhaps 4 hours. Plugging it (and my phone) in was the first thing I did in town, and sometimes I left town w/out a full charge. And I carried a light external battery, for emergency power (but thankfully never needed to use it for steri-pen.)