I used the Steripen Adventurer on one trip and returned it to REI. The switch was so stiff I had to get help turning it on and off--not a good idea when most of my backpacking is solo! I used it at the Washington coast where the water is slightly brownish yellow from tanins due to decaying swamp vegetation upstream. It is clear--no floaties--but does have the weird coloration. The Steripen consistently stopped working in mid-cycle and I'd have to run it 2 or 3 times to purify each quart. I took the directions with me and followed them very carefully. My son, an electrical engineer, couldn't make the thing work for him, either. As you sit by a mosquito-infested creek, stirring and stirring for what seems like forever for each quart, consider how much time you'd save with either a gravity filter or (even lighter) chlorine dioxide tablets, either of which can be used in camp. Fortunately I had a sufficient supply of the latter that I put the Steripen back in my pack after a day of this and used the tablets instead.

If you insist on using this gizmo, I'd take one Steripen for each person and let each person treat his/her own water. I'd also take an ample backup supply of Katadyn MicroPur or AquaMira chlorine dioxide tablets.

With the variety of pump filters, gravity filters and chlorine dioxide treatments available, there's no need to carry all your water from home for a backpacking trip unless you are going into the desert with no water sources. Water is HEAVY!

You'll find more info on filters by searching the Backcountry Health and Safety section. Search the archives, too. Be sure to read the instructions in the sticky post at the top of General Discussion on how to search--you have to change the date parameters from 1 week to something longer.