Use Carbon Filter before or after SteriPen?

Hi Simon,

The only basis I can think of for this decision is if your prefilter also has a mechanical component (debris screen) in which case I'd filter prior to UV treatment. UV will be more effective in less-turbid water. Also, since bacteria cling to particles, you'll be reducing the biological contamination the UV needs to treat.

Hope this helps.

Hi Rick,
Forgot to mention that I'll be using a SteriPen Prefilter first (to remove the particles).

I'd sure like to use the carbon filter after the SteriPen prefilter but before the SteriPen, but the kit gets more complex with juggling an intermediate container (say another Nalgene Cantene) to use to force the water gently thru the carbon filter, then use the SteriPen: scoop, pour, switch prefilters, squeeze, purify, pour — and only for 1 L at a time.

Hi Simon,

I see your dilemma, and at the end of the day I can't envision a significant technical reason to prefer one sequence over another (carbon-UV/UV-carbon). I'll still give a faint nod to carbon first, since older carbon can shed bacteria.

I can't find a reference to the Katadyn carbon unit you're considering, but have you also considered a DIY carbon+mechanical prefilter that would combine those functions? It could simplify your workflow.

Thought about a mechanical device for the carbon filter, but weight starts to play an issue, even if it's DIY. I studied the inside of my old Sawyer water bottle to see if part could be butchered, but the Katadyn carbon filter is leaner and simpler.

Also thought about a gravity system as it wouldn't need the extra container either, but I'd rather stick with streamside or lakeside, on-the-go treatment.

If I come up with any further ideas, I'll post-back.

Thanks for your input, much appreciated.

Simon