Roving Blue O-Pen Review

As someone who currently owns 6 different water filters for the backcountry, I was excited to find out there is something new so I jumped at the chance to test the O-pen for Seattle Backpackers Magazine. The pen arrived the day before a late July backpack trip to Mt Rainier’s east side up to Summerland and Indian Bar to see if the mountain was finally thawing out (it was). 

As a backpacker aspiring to finally get ultralight, I knew good things can arrive in tiny little boxes that weigh next to nothing. My first words to my husband upon opening it and seeing the pen were “how long until I lose this thing!” It really is the size of a pen and only weighs 1.2 ounces. It’s black and could easily be set down on the trail never to be seen again. I add reflective orange striping to some of my easy-to-lose gear and this pen will get some of that.

Good thing I didn’t just head out the door and into the backcountry after getting the O-pen.  The pen comes with NO instructions (they say the instructions are constantly evolving) so it sends you online to do some reading. Instructions are simple. Unscrew the cover, stick the end in water, push the button and it will do its thing over the next 40 seconds. Do it once for 8 ounces and twice for 16. Swirl it a few times and give it at least five minutes for the ozone to deplete (and destroy contaminates). The website also has an explanation of the science behind it which explains the technology in greater detail. Ozone for disinfection is definitely not new or revolutionary but being able to package the technology in a tiny pen to create ozone (O3) from H2O is a great leap forward and I found myself both skeptical and excited. A quick test on my kitchen counter showed it worked (bubbles were visible and an odor of ozone was present). Unfortunately, it’s way beyond my capability to use it on water with giardia spores and show the result. But I also can’t do that with any of my other purification systems either so they all require a bit of faith in the product.

The instructions said to only use on clear water. If the water was visibly cloudy it needed to be pre-filtered. I always carry a backup purification system so I was bringing a filter and chemical drops anyway. However, the mountain had such beautiful clean water I never pre-filtered. In all, I filtered about 15 bottles and I never had to recharge. I liked that it was very quick as compared to my gravity filtration system but a single pen in a larger group wouldn’t have been practical. I can see it being very useful for solo hikers that like to scoop up water and go and definitely don’t want to make the effort to squeeze through a filter or wait for a gravity system. All I had to do was fill up a bottle of water from the stream, clip the pen onto the rim, turn it on and keep walking. About a minute later I’d swirl it and wait five minutes and it was ready to drink. No wet filter or bags to put away. It could be very popular with trail runners or anyone going for a FKT. I certainly see the use for travel as well to disinfect quickly and discretely in foreign restaurants. 

This pen definitely rates 10/10 on some parameters, especially for convenience and weight. The biggest con would be that it would be hard to tell if it wasn’t working. The lack of the blue LED lighting up would be obvious but it does seem possible the LED would work even if ozone wasn’t actually being produced. Ozone turned out to be harder to smell than I expected (and as a lung irritant you really don’t want to be doing this anyway).  That left examining it for bubbles which is easy enough if you’re holding still, have good light, and are looking through a clear bottle. However, backpacking doesn’t always provide those conditions.  At $149 it is expensive but if the longevity is good and it can be used for multiple purposes it’s worth it. It’s definitely staying in my water purification arsenal and I hope the company continues to refine and develop new products as this technology could have a huge impact worldwide.









  • Very light weight
  • Quick to use


  • Easy to lose
  • Difficult to tell if working

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