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SteriPEN Ultra

Let there be light. 


  • 6oz
  • UV water purifier
  • Kills it all; Bacteria and Virii in 90 seconds
  • $99.00

Initial Impressions

I've never been a believer in the black magic ways of UV filtration. I need my water to go through something, a ceramic filter, hollowcore fibers, a sock, a pleated filter…something. 
For the JMT, I had two options- Replace the filter element on my MSR HyperFlow or take a chance on a SteriPEN.

SteriPEN was on sale. It was a sign.

It was simple out of the box. The Ultra as an internal Lithium Ion battery that is rechargeable. Other models use AAs or CR123s or A combo of removable rechargeable batteries.

We were taking cameras, phones, and a solar panel so Internal rechargeable was the best fit.

The Ultra has a screen interface that other models don't. The screen helped me bridge the gap and ease my skepticism. It has a countdown timer, battery life indicator, and lamp life indicator.


Since water is never far and refills are frequent, SteriPEN was the perfect candidate for the JMT. It purifies your 1 liter nalgene in 90 seconds without a lot of ceremony (pull out filter, sink prefilter in the water, screw on to bottle, pump for a while, shake filter dry, put back in pack)

Listed lamp life is 8,000 treatments, battery life on a full charge is 50 treatments.

It held a charge very well and charged quickly from the solar panel battery pack. The SteriPEN includes a cover for the lamp element. This is an essential piece. Somewhere along the trip, through some small impact, the cover got a small crack in it. If the purifier didn’t have that, or if it was in a more exposed spot- broken lamp.

The lamp is tough, though. It's encased in polycarbonate and by no means fragile like a fluorescent tube light.

It never failed, it was quick and easy, and we never got sick. I'm a full convert.


All water isnt equal. Thicker silt or tannin laced water is going to be hard for the SteriPEN. There is no prefilter (you can buy or make one; a clean bandana or pantyhose will get the big particulates out) but otherwise, what you pull form the stream is what you drink.

One of the best things is you are able to taste the water for what it is. All but one stop at garnet lake was amazingly delicious.

You have to have a nalgene or bottle shaped bottle. Bladders, bags, and similar containers don't lend themselves well to the SteriPEN.

1 liter at a time is the SteriPEN's max capacity. It will do half a liter in half the time (there's a function for that)

Last Words

They aren't for everyone or for every hike, but for the majority of what I do and places I go, SteriPEN fits the bill and performs exceptionally well. At no point did I wish for my other filter, and at no point did I need to break out the back-up tablets I had. Check the different models. Some are lighter, simpler. Big difference is going to be the battery situation. Get what works.  

Overall Arbitrary Trail Score (OATS)

9.8 Gots to have water. Keeping it from the solid 10- sometimes the lamp wouldn't turn on immediately when the timer started. After a moment or a light tap it would fire up. 

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Best since Day 1.