Here we review the SteriPEN Adventurer Opti handheld UV water purifier. This is one of many ways to get water on the trail. Unlike filter based hydration systems like Platypus, BeFree and Sawyer, the SteriPEN uses UV light to kill bacteria. It achieves this by destroying their DNA.

SteriPEN offer a few different models, some are battery powered and others USB chargeable. The adventurer model is battery powered.  Whilst many hikers carry a USB battery charger and/or solar charger, a couple of CR123 are much lighter. One battery is good for treating 100 x 0.5liters. The bulb is good for 8,000 liters of water and the unit weighs in at 0.2lbs.  Since the SteriPEN uses UV light to kill the bacteria, the light needs to actually get to the bacteria. For this reason, it is important to filter cloudy and water with particulates through a bandana, buff or other kind of cloth. If the light does not shine on the bacteria because it is hiding inside some dirt, it will not work effectively. In clear water, the SteriPEN will destroy over 99.9999% of bacteria, 99.99% of viruses and 99.9% of protozoa. Filtration systems usually do a reasonable job at removing much of the taste from the water, UV light will not help with bad tasting water.

The Adventurer comes with a plastic cap to protect the bulb. This bulb is somewhat fragile and so a back-up water purification system (like some Potable Aqua tablets) is a good idea.


  • Fast
  • Easy to use with clear water


  • Does not help with taste
  • Unclear water needs filtering to remove particles
  • Requires power


Whilst UV does a similarly good job at removing/killing bacteria, it somehow doesn’t ‘feel’ as effective.

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