Dummies guide to Steripen

I’m walking 640km across Jordan, and the days are counting down remarkably fast. The point of the trek is not only to challenge myself but to raise funds for @MSF_UK as I’ve written about extensively, start at number one and work on through to ten. If you believe in MSF’s work around the world or simply like my blog please head over to my just giving page and donate a few Pounds, Euro, Shillings or dollars to the cause.

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What is a SteriPen

The SteriPen is a super useful hiker gadget which really works for purifying water for drinking using UV sterilization. It is definitely bigger than a pen and my backpacker version weighs in at about 100g.

To use it you press the only button, immerse the UV lightbulb tube into the water you want to sterilize. the light will only come on when it is properly covered in water for safety reasons. Wait until the light goes out, and a green light flashes telling you the cycle was completed and that is it. water good enough to drink.



  • Simple to use
  • Quick , 1 minutes vs 30 for tablets
  • Kills majority of pathogens
  • No weird taste
  • Effective
  • Looks like a mini light-sabre
  • No workout squeezing bags through filters


  • Doesn’t remove debris, so pre-filtering might still be required
  • If it breaks/batteries run out you must have backup and my version has a weird battery size, hard to come by
  • Max 1 L at a time
  • More expensive than tablets

The problem

Your risk of drinking water contaminated by pathogenic viruses, bacteria or parasites increases when drinking from water sources near population centers, high animal density, migratory bird routes or other bird population centers. Popular camping spots pose higher risk and it is essential to follow good waste management after pooping.

Virus – most common viruses in water include, Rotavirus, Noravirus, Hepatitis alphabet, enteroviruses. Viruses are tiny and most water filters don’t remove them as their small size allows them to pass through the filter pores.

  • Can cause stomach cramps, diarrhea, vomiting as well as hepatitis and meningitis

Bacteria – Vibrios including Cholera, Campylobacter, Escherichia coli,  Legionella, Salmonella, Shigella

  • Can cause stomach cramps, diarrhea, vomiting, death

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Parasites – mostly protozoan: Giardia  and Cryptosporidium. Can be tough to kill by chemical means due to thick outer protective coats which make them resistant to chemicals used in water treatment

  • Can cause diarrhea, vomiting, cramps, fever, chills and be persistent as they are often confused for bacterial causes, yet don’t respond to regular antibiotics

Global hydration has a terrifying summary.


Boiling is highly effective at killing any water borne pathogen. water needs to be at a rolling boil for over 60 seconds (at sea level). But boiling requires the use of fuel which may be in limited supply or isn’t convenient and you can’t have a refreshing drink of boiling water straight away!

Filters, as mentioned don’t remove viruses, and only remove bacteria and parasites  larger than 0.3 microns effectively. Filters can become easily blocked and take time and energy to work.

Chemical treatments, like chlorine and iodine are not very effective against parasites, can make the water taste weird and requires time to work. But tablets are superlight to carry.

UV such as Steripen, can be effective against most pathogens, but only if the water is clear enough for the UV light to have sufficient contact time with the microbe to kill it.


So how do you decide?

  1. Research which pathogens are common in the area you are hiking in
  2. Are they viral, bacterial, parasites or a mixture
  3. Think about your hiking style – ultralight, no cook, car camping etc
  4.  Consider a combination

In an ideal world, where time and weight are not an issue, I would filter water to remove large partials, dirt, parasites and then boil all my water. But this isn’t practical for me while hiking.

My best fit option is a SteriPEN for ease of use and quickness and if water quality is a major issue I have the option to boil water at night and a fall back of purification tablets. But it is up to you to determine your best fit for your trip and risk levels.

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