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SteriPEN Ultralight UV Purifier

rated 2.0 of 5 stars
photo: SteriPEN Ultralight UV Purifier water purifier

2.6 ounces, no pumping, nothing to clog, 90 seconds treated water


  • lightweight
  • small
  • doesn't impart any taste
  • can't clog


  • it's electronic
  • my first one was a dud
  • need a wide mouth bottle

I have a Steripen Adventurer that I've used off and on for several years.  It's never given me any trouble, but utilizes CR123 batteries, while my headlamps use AAA. It's pretty light, but not crazy light.

The Steripen Ultralight weighs under 3 oz (2.6 oz) and is very compact. It utilizes a rechargeable battery (via a USB Micro). I purchased one a couple of months ago and took it on a short (3 days/2 nights) backpacking trip. It worked fine for the first day and a half, but then quit working. I used Aquatabs for the rest of the trip.

When I got home, I fully recharged it. But after treating one liter of water in the kitchen, it quit working again. Not exactly installing a lot of faith in it. I called Steripen (Katadyn) and they quickly sent me a new one. This time I was going to thoroughly test it in my kitchen before taking it in the backcountry. I treated right at 20 liters before recharging and then another 20 liters without incident.  I've since had it out on a couple of backpacking trips and several long day hikes. It's worked flawlessly, I think I simply had a dud.

I like the fact that uv imparts no taste to the water (vs tabs), there is no wait time, and it doesn't clog. As it is electronic, I always carry a dozen Aquatabs as backup; I do the same if using a filter though. It takes 90 seconds to treat a liter of water and no pumping. You do need a wider mouth bottle; I've gone back to Nalgenes for the most part as I've had a few bottles develop holes at the worst times.


20 liters of treated water nets me about three days without recharging. I do always carry a charger with me as I use a phone gps and carry an inReach Mini. I have several chargers depending on length of trip. But even my smallest charge—a Jackery Mini (~3000 mah)—can charge the Ultralight a couple of times.

Thus far I'm pretty happy with this little UV purifier.


I've used a Steripen in the past for several year; the Ultralight I've used on a few backpacking trips and several long day hikes.

Source: bought it new
Price Paid: $69

I bought this product years ago, when it was newly on the market.
There are too many "Caution Statements" not fully covered in the instructions.
All of this may have been addressed since then... Perhaps not.


  • Will not sterilize water droplets above the waterline and the threads of bottle or the cover.

(From ORIGINAL Instruction Booklet)
Notice in the instruction book's photo, there are NO DROPLETS on the glass, above the water line… Because they will NOT be cleaned.

Cautions—not fully explained!

These are not listed or explained in the instruction booklet!

When you dip your Nalgene bottle into the source water, the threads get contaminated and therefore the cap gets contaminated too when you put the cap back on.

Any spillage over the top, or water droplets above the water line in the container are suspect contamination.

Micropur (and other products too) recommend that after dissolving their product in the water, that you crack open the bottle while holding it upside-down and let a bit of water flow out of the cap. The activated cleaning solution then cleans the cap and threads on the outside where you put your lips. ALL the water inside the container is cleaned too, not just the water below the water line.

Instruction page #4, Item #5 says:

• “SteriPEN is not intended to disinfect water above the surface of the water in the container, i.e., droplets of water suspended on the side of the container”.

Caution: You cannot clean the cap and threads or water droplets above the waterline with the SteriPEN product”.

Note: The product is designed to kill all micro-organisms. Giardia lamblia is 2 microns. They could be anywhere where there is even the smallest speck of water.

Instruction #4 on Page 1, says:

“Note: If visible light is not evident, SteriPEN’s lamp is not on, and water should not be consumed.”

Caution: The light is extremely difficult to see on a sunny day, even if you are in the shadow of a tree or rock or try to shadow the product with your body.... so how would you know for certain that it is working?


Tried it for one backpacking trek, then returned to REI.

Source: bought it new

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Price Historic Range: $69.93-$89.95
Reviewers Paid: $69.00
Technology UV
Weight 3 oz
Battery type Internal USB Rechargeable Lithium-Ion
Lamp life 8000 activations
Volume options 2 clicks = 1 liter
Effective against microorganisms / suitable for clear water only
Treatment size 1 L in 90 seconds
Size 13 x 3.5 x 2.2 cm
Product Details from SteriPEN »

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