SteriPEN Review

by C.D.

I received the STERIpen® Sidewinder the other day from Ready Made Resources and I promised Rourke a review very soon, right after I tested it.

To be honest I didn’t know a lot about UV sterilization other than the SODIS method that I have tried before with success. Frankly I was a bit skeptical of a 90 second exposure to UV being safe for drinking. If you are not familiar with the concept, the UV light damages the DNA strands of a virus in your drinking water, rendering it incapable of reproducing into your body. Basically the same with germs and most single cell life.


The colorful STERIpen® Sidewinderbox contained instructions in English, German, French and Spanish so just about anyone on the planet can read them (or have them translated) but there are more than enough descriptive pictures to use the purifier without reading a word. There are additional pages offering tips on the use of the pre-filter and general purifier usage tips. The Sidewinder itself was packaged with the included one liter “BPA FREE” bottle, a rubber protector sleeve for the UV bulb, a handy carry cap for the bottle and the prefilter. The prefilter looks/is a cap for the one liter bottle with a fine-mesh filter sitting in a “bowl” on the top. The mesh filter is removable for washing and clearing of debris encountered while filling the bottle. Usable life on the UV bulb is described as 8,000 liters. At 7,900 liters the LEDs will flash two red then two green to remind you to send the unit back to your nearest warranty facility for bulb replacement.

To use the Sidewinder you install the prefilter on the included one liter bottle and either pour water into the filter or submerge the whole bottle into your water source. There is a small valve on the top of the filter (the same as on a sports drink bottle) to allow for air to pass when submerging. Use of the filter is pretty much a no brainer as you do not want largish particles in the water you are drinking later. Removing the rubber UV lamp protector, you then turn the Sidewinder upside down to install the water bottle to the device. Once the rubber O-ring is sealed and the bottle properly seated turn the entire unit over, unfasten the turning handle and start cranking the charging handle. That’s all that’s really required. If you are turning too slowly, two red LEDs at the base of the bottle flash to prompt you to turn faster, once you have spun the charger for the required 90 seconds the same LEDs flash green and the gearbox to the charging handle “disengages”. By this I mean it gets easier to turn and seems like it is not “charging” anymore (it’s not) and the handle feels like a “free spin” movement. This last function was not explained in the supplied instructions but upon reflection makes good sense to keep you from over cranking. Once the LEDs have stopped flashing green, flip the unit over again, unscrew the bottle and enjoy your now safe drinkable water.


In theory.

This is all fine and dandy while I’m here in my house with unlimited amounts of Imodium nearby but what about when I really need this to work? To test this, I decided to volunteer myself (What?! I did? Wait let’s talk about this brother!) and put the Sidewinder to the test. Here at my Secret Underground Lair (and Compound) I have several rain barrels installed on the Armory and Supply Depots to augment the water shortfall to the garden in a drought. Perfect area for all kinds of nastiness to breed and multiply, waiting to “make my day” so to speak.

I began by collecting rainwater in a gallon milk jug, then using a coffee filter and funnel to filter the water into the Sidewinder’s bottle. No particulate noted and the water was very clear before we started. I screwed the bottle into the purifier, flipped it over and started cranking, counting off the seconds as I did so. Well I was off or the purifier worked well because when I got to around “64” the green LEDs flashed and the gearbox went limp. I thought I’d broken it (as mentioned above) until I noticed the LEDs. Process complete. I hesitantly put my lips to the bottle and took a swig.

The taste of the water wasn’t bad, in fact it slightly reminded me of the “city water” connected to the compound (as a back up of course, yes, yes, harrumph-harrumph) and upon declaring it “not bad” I took a bigger gulp of water. All told I drank about half a liter and poured the rest out, lest I “contaminate” someone else before the test was complete. I then crossed my fingers and went to bed. The next morning all was well with no cramps, no diarrhea or other strange intestinal dysfunction. It is now better than 72 hours since I first tested the Sidewinder with still no ill effects. I believe I will use this product again.


  • No batteries required for use
  • Long expected lifespan
  • Simple operation (Pictures of the bottom of the unit even tell you how)
  • Everything included in the package
  • Almost any water can be used provided you filter for large particles first
  • At $100 not out of reach for everyone


  • No user serviceable replacement UV bulbs
  • Large form factor (means it’s kinda bulky)
  • Required to use supplied bottle (to be honest I’ve not tried another bottle as I don’t have anything like this bottle, I use USGI canteens)
  • At $100 you are not really able to afford to put one in every APC/vehicle/BOB you own.
  • Not large enough to support a medium to large group alone.

The Sidewinder is a great bit of kit and I’m glad I have it (thanks again to MSOnline and Ready Made Resources) but it is not the end all be all of purification. This is more of a damn good backup to your main purification method. For example if you are cleaning your Berkey filters or it’s too cloudy for your SODIS bottles to be done in time, this will fill the bill quite nicely. It is also not really ready for backpacking/BOB bug out as it is fairly large compared to other purification devices. The ability to not eat into my battery stockpile while providing me potable water is a huge bonus and I will mostly likely keep it on the shelf in the supply room depot until I put it in a GHB for long trips.

[From Rourke: Thank you C.D. – glad you are happy with the SteriPEN]

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  1. I read a detailed review of the Steripen UV water purifier several months ago. It comes down to this… boiling water is much easier. Light a fire, boil water, strain out the chunks through a sock if you have to… simple. These fancy do-dads are really nothing more than a gimmick and extra cargo to haul. I’m sure they can serve a purpose but you won’t find me shopping for one. I recall the review I read stated that these units seemed to be made of cheap materials. The crank handle in particular was an issue with the reviewer.

    Anyway, I don’t really care because I’ll never waste my money on this gimmick. It becomes nothing more than a “brick” to carry around if any of the parts break.

    Hey Rourke, love your website by the way.

    Prepper Guy

    • Prepper Guy –

      Thanks for the comments- that is the great thing about this country – so many choices (at least for now).

      Take care – Rourke

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