This post may contain affiliate links.

Why Choose the Steripen Adventurer Opti for Water Purification

The SteriPEN Adventurer Opti Ultraviolet Water Purifier

Water purification with the Steripen Adventurer Opti ultraviolet light is an easy way to kill the bacteria, viruses, and cryptosporidium found in natural water sources when day hiking, camping, or backpacking.

It’s easy to use, very reliable, and works in all temperatures, including below freezing, which will ruin most water filters made with hollow fiber filter elements. The  Adventurer Opti can also be used with all types of water containers, provided you can insert the light element far enough into them including wide-mouth Nalgene or Hydro Flask aluminum bottles, CamelBak water bladders, and zip-top reservoirs from Osprey, Gregory, CNOC, HydraPak, and Platypus.

Note: Katadyn, which also manufactures water filters and purifiers, bought the company that makes Steripens several years ago. This explains why the Steripen Adventurer Opti is sometimes listed as the Katadyn Steripen Adventurer Opti at retailers.

Like all backcountry water treatment solutions, the SteriPEN Adventurer Opti, have their pros and cons and are not suitable in all circumstances. They work best with sediment-free water from mountain streams, rivers, ponds, and lakes that are free from the chemical or mineral pollutants found near agricultural, urban areas, and mining operations.

Neutralizes biological organismsDoes not work with all bottles or reservoirs
Very fastBattery dependent
Non-mechanical, no pumpingDoes not remove chemical or mineral contaminents
Effective in cold or freezing weatherNot effective with cloudy or murky water
Does not affect tasteDoes not neutralize larger organisms, i.e. worm eggs

The Steripen Adventurer Opti weighs 3.6 oz including batteries and can purify 50 liters of water up to 8,000 times. That’s more than enough for weekend trips where you’d drink 4-5 liters per day. If you use it in temperatures under 32 degrees, it’s best to store it near your body to keep the battery warm, but it can be packed anywhere in warmer weather.

The SteriPEN Adventurer Opti can be used to purify 1 liter or half-liter of water at a time. You can use it with any plastic, metal, ceramic or glass bottle as long as it has a wide enough opening so you can submerge the Opti’s light element in it. While a wide-mouth 1 liter Nalgene bottle is very convenient to use, there’s no reason you can’t use a cooking pot too.

Once submerged, you stir the water gently with the SteriPEN until the UV light goes off, which signals that your water is purified. It takes about 90 seconds to finish. It is as simple as that. The ultraviolet light destroys the DNA that lets bacteria, viruses, or cysts replicate in your gut which is what makes you sick. If you’re worried about water remaining on the threads of the bottle or container you used, wipe them dry with a clean cloth. This isn’t a big concern since your immune system can usually handle the small number of organisms remaining on the threads if any.

The Adventurer Opti is powered by two CR123 lithium batteries, which are relatively inexpensive if you buy them in quantity at Amazon. They’re lithium batteries so they’re good in cold weather and won’t freeze when the temperature drops below 32 degrees, like alkaline batteries that contain water. If you take longer trips, the SteriPEN Classic might be a better solution because it can purify 150 liters on a single set of AA batteries although it is about twice as heavy as the Adventurer Opti, with batteries.

Like all water treatment solutions, it’s important to carry a water purification backup if your primary method fails. For example, I always carry Katadyn Micropur Chlorine Dioxide Tablets as a backup water purification method in case my primary method – be it a Steripen, a gravity filter, a pump filter, or squeeze filter – breaks, clogs, the batteries die or it fails somehow. I don’t use Micropur tablets all the time because I prefer the taste of non-chlorinated water and they’re a fairly expensive solution, but they reliably purify silt-free water stored in any container and at any temperature.


The Steripen Adventurer Opti is an easy-to-use water purification solution that can treat up to 50 liters. It’s powered by two lithium batteries and good for weekend trips with a couple, assuming you drink 4-5 liters of water per day or carry spare batteries for even longer-term use. Water purification with ultraviolet light is a very safe and effective way to purify natural water sources for human consumption, it’s very fast, and doesn’t rely on arduous squeezing or pumping to work. It can work with any water container that has a large enough opening to submerge the light element such as a wide-mouth Naglene bottle, a Hydro Flask bottle, and most hydration bladders with zip-tops.

Shop at Amazon


Disclosure: The author purchased this product with his own funds.

See Also:

SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.


  1. Steripens don’t work on moose tapeworm eggs. Witness Isle Royale, where the Rangers will tell you how ineffective MSR Guardians are at removing liver-destroying cysts. They also do not work on agri-chemicals. One device that does operate under horrible circumstances is FirstNeed by General Ecology. That chit gets almost all of it out from your drinking and cooking water. It is no more odious to utilize than Guardian, granted Guardian has a LOT more life. I stick with the General Ecology FirstNeed because the compromises favor my health.


    UV Purifiers Details
    SteriPENs and other UV purifiers have not been manufacturer-tested for hydatid tapeworm, a common parasite found in Isle Royale waters and cannot be considered effective. Hydatid tapeworm (Echinococcus granulosus) is a parasitic tapeworm that requires two hosts to complete its life cycle. On Isle Royale, moose host larval tapeworms, which form hydatid cysts in their body cavity. In wolves, larval tapeworms mature and live in the small intestine. Adult tapeworms produce eggs which are expelled from wolves in feces, and consequently, the waters of Isle Royale. Find out more about hydatid tapeworm on the Center for Disease Control’s website.

    More About Water Purification
    For detailed water purifying information, visit the National Park Service Backcountry Health website. If you have further questions regarding safe drinking water, contact the park.

    Cyanobacteria and Harmful Algal Blooms
    In recent years, harmful algal blooms have been present periodically at several inland lakes. When filtering and/or purifying water, these HABs must be avoided completely as there is currently no viable method for removing or subduing cyanotoxins in the backcountry.
    Learn more about harmful algal blooms, how to identify them, and what to do if you find them.

    Stay up-to-date on the Current Conditions at Isle Royale National Park, including any current advisories regarding HABs.


    I don’t have a dog in the fight. But I am more widely traveled and geared out over time than many of you. I report it as I see it but you, fortunately else unfortunately, are free to do YOU. Hopefully you report back positive knowledge.

    • As you may likely already know, you can sometimes visually identify an algal bloom but you cannot visually determine if that algal bloom contains harmful toxins. Toxin identification requires testing known as the ELISA Method which requires a water sample collected and sent to a lab for analysis. To be safe, you should just seek a different water source to filter and drink.

      • This is solid advisement. On a limited territory, unlike Alaska, where I spend a lot of time and hope to retire flying bball sneakers to kids North of the Circle, as I’ll be too old to fly pax, you cannot be confident nowadays in discerning GL algae toxins. Your nose may alert you but it’s unreliable. Fortunately, Isle Royale staff and scuttlebut will share at least hushed some info NPS doesn’t print based on ranger testing. They do an acceptable job and then some. Just returned from a leg stretcher Isle Royale, now l9oking at you, Cascades.p

  3. I have a Steripen that is USB rechargeable. The documentation says it can do about 20 1-liter treatments per full battery charge and a lamp life of 8000 activations. I wonder if you mean something similar when you write “50 liters of water up to 8,000 times”.

Leave a Reply

Your email address will not be published. Required fields are marked *