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Reviews > Water Treatment > Ultraviolet > SteriPEN Adventurer Opti > Test Report by Curt Peterson

Hydro-Photon SteriPEN AdventurerOpti Water Purifier
Test Series by Curt Peterson

Initial Report - May 2010
Field Report - August 2010
Long Term Report - September 2010


Below you will find:

Initial Report Contents
     Tester Background and Contact Information
     Product Specifications
     Initial Impressions
     Initial Report Summary

Field Report Contents
Long Term Report Contents


SteriPEN AdventurerOpti


Initial Report

Tester Back+ground and Contact Information

Name: Curt Peterson
Age: 38
Gender: Male
Height: 6 ft 3 in (1.91 m)
Weight: 270 lb (122 kg)
Email address: curt<at>backpackgeartest<dot>org
Location: North Bend, Washington, USA

I live in the Cascade foothills, just 20 mi (32 km) from the Pacific Crest Trail via trails leading right from my backyard. My outdoor time in Washington is spent dayhiking, backpacking, climbing, fishing and skiing everywhere from the Olympic coast to rainforests to Cascade volcanoes to dry steppe. I played football in college and often evaluate products from a big guy perspective. My typical pack load ranges from 11 - 20 lbs (5-9 kg) and usually includes plenty of wet weather gear.

Hydro-Photon SteriPEN AdventurerOpti Specifications

  • SteriPEN Weight: 3.6 oz (103 gm) measured on my scale | 3.6 oz (103 gm) manufacturer claim
  • SteriPEN Sack: 0.8oz (25 gm) | Weight not listed by manufacturer
  • Maximum Height: 6.1 in (15.5cm) manufacturer claim
  • Maximum Width: 1.5 in (3.3 cm) manufacturer claim
  • Maximum Thickness: 1.0 in (2.2 cm) manufacturer claim
  • Batteries: Two (2) CR123 Batteries (included)
  • Battery Life: 100 16 oz (.5 L) treatments claimed with disposable batteries
  • Battery Life: 40 to 50 16 oz (.5 L) treatments claimed with rechargeable batteries
  • UV Lamp Life: 8000 treatments claimed
  • Manufacturer Website:
  • MSRP: $99.95 US

SteriPEN Adventurer Opti Initial Impressions

Water treatment has always been one part of my gear kit I haven't been happy with. For most of the last 20 years I've treated water not because I want to, but because I feel like I'm supposed to. I have tried just about everything. From iodine to chlorine dioxide tablets to bottle filters to gravity filters to a number of different pump filters, just about everything has left me frustrated. The UV filters like the SteriPEN are the one technology I have not used, and I have high hopes that it will be the solution to my treatment needs.

I am fortunate to live in the Pacific Northwest where we have fantastic, clear, clean water and plenty of it. I rarely carry water on the trail - often the single heaviest thing in many backpackers' packs. On the western slopes of the Cascades and the Olympics in particular, a backpacker is rarely more than a mile or two - just a half hour or so - from water. This reality has greatly influenced my treatment style. I want it quick and easy. I prefer to stop on the trail, leave my pack on, pull some water out of a river, creek, or stream, treat it as quickly as possible, drink it down, and keep moving. I've given up on pumps. They are much too slow and have way too much going on with hoses everywhere and parts to put together and cleaning and back flushing. They are often the heaviest treatment method as well. Tablets simply take way too long and are not intended to be used "on the go". Gravity filters are great for camp, but not an ideal on-the-run solution. They usually have the multiple-hose, multiple-parts challenges that pumps have. Because of these issues, bottle filters have become my preferred method of water treatment. They're quick, keep the water cold and tasty, and are simple in design and construction. The main problem with bottle filters is that there are plenty of low quality brands, they typically have the worst filtering abilities, and can be hard to suck and squeeze. My favorite bottle filter has been out of business for years and the last of my supply is getting thin. To be honest, all these annoyances have led me to "go wild" for a good chunk of my backpacking. If it's remote, cold, clear, and I know the source I'll simply dip and drink. Probably not the smartest idea, but that's where I am right now. In Wilderness Areas I don't lose a lot of sleep over this, but in areas with free ranging cattle drinking untreated is not something I'm eager to do. The idea of a treatment method that is quick, simple, has no moving parts, and is highly effective is definitely appealing. I am doing more trips with my 7 year old, and while I'm dumb enough to not treat on my own water, I'm not willing to experiment on him.

SteriPEN Boxed
SteriPEN AdventurerOpti Full Packaging

SteriPEN AdventurerOpti Contents

The SteriPEN AdventurerOpti arrived safe and sound to my home in what appears to be the retail packaging. Everything was included and it seems ready to go right out of the box. It looks just like it does on the SteriPEN website, which offers a more in depth description of the device, including a short video. The site is easy to navigate, well organized, and covers the various SteriPEN products thoroughly. Probably the most useful part for someone who has just purchased a SteriPEN is the Frequently Asked Questions (FAQ) section that covers a lot of the basic information on how to use the SteriPEN. There is also an accessory section, though not much is available for the AdventurerOpti. The one item that might interest folks who frequent dirty water areas is a prefilter as the SteriPEN is supposed to be more effective in clearer water. Here is the website description for the AdventurerOpti:


The smallest, lightest SteriPEN®, the AdventurerOpti, uses a revolutionary optical eye to sense the water. The patent-pending technology provides safe use and the standard insulating sleeve around the UV lamp allows purification in even the coldest of waters.

Fast, Light, Easy and Effective, the AdventurerOpti provides the ultimate protection from waterborne illnesses. Giardia, cryptosporidium, bacteria and viruses are all destroyed –in seconds—by SteriPEN® UV light. Similar to other SteriPEN models, the Opti purifies 0.5 L (16 oz.) in 48 seconds and 1.0L (32 oz.) in just 90 seconds. The UV lamp provides up to 8,000 one-liter treatments.

The new optical sensor doubles as a convenient LED flashlight.  It’s a great backup light when camping or taking a night-time walk to refill your water bottle. The Flashlight mode is activated by pressing and holding the single button down for 3 seconds. The clear lamp cover focuses the LED light.

I'm looking forward to testing the AdventurerOpti. I'm not worried about its effectiveness. Everything I've read about UV treatment has me convinced it's a solid method to purify water. Probably my biggest concern going into the test is durability. It feels super tough, has a nice thick rubberized coating on the main part of the unit, and seems very solid, but it does contain a big glass element that houses the UV wand. That said, I take a number of things that are much more fragile into the backcountry and don't have any problems with them. I'll be careful not to drop it on rock from chest height, but barring that I can't imagine it will need to be babied much. It does come with a tough plastic piece that covers the wand and a neoprene case, so there's plenty of protection built in. 

Depending on what bottle is used with the AdventurerOpti, this solution has the potential to be one of the lightest treatment methods I've used. Especially if I just use my normal camp cup or mug, the only weight added to my gear list would be the unit itself. It's lighter than any bottle filter I've used and is probably only outdone by tablets. Trying out a number of different bottles and seeing which fit well and work in tandem nicely with the SteriPEN will be a significant part of my testing.

The two "new" features of the AdventurerOpti that have not been in previous models are the water sensor and the LED light. The sensor is interesting. Apparently it senses whether or not the wand is correctly placed in the water so the likelihood of an ineffective treatment is greatly diminished. I haven't used the older SteriPENs, so I have nothing to compare this to, but as long as it works, it sounds good to me. The LED light doesn't seem like that big of a deal to me. I suppose it never hurts to have another small light around and it takes up no space or weight, but the presence or absence of the light wouldn't affect my decision to choose this product or not at all.  

The battery life is also not that big of a concern to me. SteriPEN claims 100 treatments of 16 oz (.5 L). I figure even if they're optimistic by 100%, 50 treatments would last me at least a week and that seems very reasonable. Perhaps through-hikers will have concerns with battery life, but even having to carry spare batteries seems to be small inconvenience if the SteriPEN meets all of one's other water treatment needs. Most of my trips are 3 or 4 days, so I'm not too worried about battery life at this point.

I look forward to getting some on-trail usage of the AdventurerOpti and see how it works in the real world!

Initial Report Summary

The AdventurerOpti looks like an almost perfect solution for my style of treating water on the trail. It appears to be quick, light, effective, and simple. If it can hold up to trail usage and stayed powered for a weeklong trip, it could be the solution I've been looking for. I can't wait to find out!

Field Report

The SteriPEN AdventurerOpti has been a welcome addition to my gear kit. In fact, it has probably changed my backcountry routine more than anything since making the switch from tent to hammock. Looking back over the last decade or so, most of my gear changes and upgrades are minor improvements in products, weight reductions, or style changes. Only a few items have fundamentally changed the way I travel in wild places. I dare say that the SteriPEN is one of those items. I have never been very satisfied with my water routine. Tablets, bottle filters, gravity filters, and going treatment-free all have their pros and cons. The SteriPEN is the first treatment method I've used that combines no-brainer simplicity, speed, and reliability in a way that takes the chore out of water treatment.

I've treated somewhere between a dozen and two dozen quarts (liters) at this point. I've used it a few times at local lakes just to get used to it, but the majority of the use came on a trip into the Hoh Rainforest in Olympic National Park. On that trip, all the water treated came from the Hoh, which is a milky turquoise river with glacial silt throughout. Near the banks where I got all of my water the river seemed a bit clearer. I could see down into the water about shin deep. This is easily the cloudiest water I see in the backcountry. The Cascade and Olympic rivers and lakes are commonly stunningly clear and free of sediment suspended in the water. I figure this was about the most chunky water I'll use with the SteriPEN and it handled it just fine. A few weeks after the trip I've suffered no gastrointestinal issues, so I'm quite confident it did its job. To be fair, the chance that the Hoh contained many bugs is pretty remote, but it's nice to know I was protected all the same.

Using the SteriPEN definitely requires re-thinking the water routine. I usually take a dip-and-drink bottle filter and a Platypus bladder on trips or a gravity system for camp. While the bottle filter system is quick, it's work to squeeze it through and is slow to drink from. It works, but when I want a nice big gulp of ice cold water, it just doesn't cut it. My gravity setup is slow and finicky. I've never got it to really work well and although it can filter a lot of water passively, it's certainly more of an in-camp setup that requires all kinds of fussing with multiple bladders, hoses, hanging, and tweaking. For groups, I think it still has some benefits, but I sure didn't miss it at all on this this past trip. For the SteriPEN, I carried the unit and a lightweight mug in a side pocket on my pack. Any stop along the trail near water and I was 30 seconds away from a cold cup of water. If I wanted to carry water I would treat it in the mug and then pour it into the storage bottle. An open top mug (or cook pot) is the ideal treatment vessel since it gives easy access and allows for no-resistance gentle stirring. It will work with a Gatorade bottle, but the fit is tight and only the very end fits. This makes stirring difficult and it's easier to accidentally move the water sensor out of the water and trigger a "failure" light. Overall, I found the lightweight mug and SteriPEN combo easy to pack and unpack quickly, ridiculously simple to use with little thought and essentially no work like pumping or squeezing, and not a second thought given to prefilters, backflushing, clogs, or treatment wait times. Push a button, relax for 30 seconds, drink.

Using the SteriPEN took one outing to figure out. I took the directions in case I ran into trouble, but once a successful use has been achieved it really is amazingly simple. The only thing that requires any amount of attention is to keep the water sensor submerged. After pushing the single button once for a quart (liter) or twice for a pint (half liter), the wand is dipped into the water to a depth sufficient to cover the wand and the small sensor at the base of the wand. The blue light comes on and a green LED comes on indicating that the water is being treated. The blue light actually seems to pulse as it's treating. When it's done, it simply shuts off. The only problem that can arise is if the water sensor is lifted above the water line during the treatment. If that occurs, the green LED turns red indicating that the process should probably be re-started. This can happen by tilting the SteriPEN while stirring, so it's best to keep the wand a little deep or hold it vertically so both the wand and the sensor stay appropriately submerged. Again, after treating just one or two mugs of water this becomes routine and there's not much attention required.

SteriPEN Field
SteriPEN doing its thing in Olympic National Park

I have had only one small concern so far with the AdventurerOpti. At the gap where the battery cover meets the unit, there is supposed to be a rubber band gasket. My unit either did not come with one or it has come off of the SteriPEN and disappeared. I did notice that the gap around the battery cover is not uniform. It seems to seat a little lower on one side than the other. I sent an e-mail to SteriPEN asking about replacement gaskets and got a reply within a couple days asking for a shipping address to send some spare gaskets. Great customer service as far as I'm concerned.

Rarely does an item come along that changes the way I backpack. Most things are an evolutionary change. A little lighter, new materials, etc. I've been trying to declutter my kit, and the SteriPEN is a boon in this regard. This system is so simple, so small, so light. This is completely changing the way I think about water. No hoses. No clogs. No bags. Super clean, very light, and ridiculously simple. It's hard to be sure, but I think I stay more hydrated with this because the hassle of water treatment is lowered so much.

I have more trips planned for the Long Term Testing period, including a 6-day trip into the North Cascades. I will be relying on the SteriPEN for all of my water treatment, so battery life, durability, and day-after-day usage will noted.

Long Term Report

I have used the SteriPEN AdventurerOpti on at least another half dozen occasions since the Field Report. I figure I've treated about another 30 or so pints (half liters). I've used it a couple times on dayhikes, a quick overnighter, and three days in the North Cascades. The North Cascades trip was supposed to be 6 days, but after hanging out in the rain under tarps for a couple days we abandoned the climb to the high country. Disappointing, but probably prudent. The SteriPEN was my only water treatment option on all trips.

The SteriPEN has definitely changed the way I think about water. It has caused a rethinking of my entire water treatment system and I'm still rethinking it even after using the SteriPEN for the past four months. My current setup is to head out with just a pot, a mug, and the SteriPEN. That's it. No bladders. No hoses. No bite valves or screw tops. In theory I could even eliminate the mug for a minimalist setup, but the convenience of a mug is worth the pretty small additional weight. An ideal kit in terms of space and protection would be super light, tall, skinny drinking cup that the SteriPEN could fit completely inside. This would cover drinking, storage, and protection. Perhaps that is what the next component of my water kit will be. This would offer me one simple, compact item to carry on the side of my pack that is always easy to grab and ready to use. I carried the neoprene case on all trips during testing but will probably leave it behind in the future. It's fine, but the SteriPEN is much tougher than I anticipated and it now seems like overkill. I usually carried it in the shoulder pocket of a Granite Gear pack. It's always handy. It's always quick. Just 30 seconds to water with no pumping, no hoses flopping around, and nothing's wet afterwards.  

The purifier has proven to be dead simple to use. It has never failed once since I got the hang of submerging it properly. I'm still on original batteries after probably 50 or so pints (half liters). I have experienced no durability issues and it looks as new as the day it arrived. SteriPEN sent a bunch of replacement gaskets in just a couple days after I noticed that mine was missing during the Field Report. There was no cost to me and they included enough spares to last a lifetime I imagine. They get an A+ for customer service as far as I'm concerned. Full disclosure: I did not identify myself as a product tester and as far as I know they treated me as they would any customer.

If I was going through my entire gear kit and giving out an award for 2010, it would be the SteriPEN in a landslide. It's been a long time since something has fundamentally changed the way I do things in the backcountry. As noted earlier, probably not since going to a hammock system have I had such a shift in one of my core backpacking activities. Different types of stove kits or even going to open fires cause some rethinking, but the idea is still the same and the systems don't truly vary by much. Different clothing systems add different functionality or weight savings, but essentially all just vary in degrees of weight, warmth, or water resistance. The SteriPEN has changed the very way I move on the trail. I now almost always opt for a quick dip along the trail instead of tanking up and carrying water. My pack weight has dropped by a couple pounds (a kilo) as I rarely carry any water. The way I drink in camp has changed. I treat water by the cup as I want it instead of hauling and pumping. I'm always near a water source when I camp, so this works very well for me. It has changed the way I pack. De-cluttering has been a goal for me this year, and I have no doubt the SteriPEN is currently the lightest, fastest, most convenient, cleanest, most effective solution for me. The only things lighter are tablets and they certainly aren't the most convenient or fastest. Every other solution involves pumping, squeezing, sucking, or hauling at best and untangling, backflushing, unclogging, or extended waiting at worst. 

The SteriPEN AdventurerOpti is a big winner in my book. Perhaps an even slimmer, lighter version would improve it, but it's getting into the range of diminishing returns at only 3.6 oz (103 gm). AA or AAA batteries that are more easily obtained than the CR123 size it currently uses would also be a nice improvement. As is, however, the SteriPEN is a top-notch item, tougher than it seems at first glance, mature in its development after going through a few incarnations, and proven effective and reliable. It has most definitely found a permanent place in my gear kit.

My thanks to and SteriPEN for the opportunity to test this unique water treatment method!


Read more gear reviews by Curt Peterson

Reviews > Water Treatment > Ultraviolet > SteriPEN Adventurer Opti > Test Report by Curt Peterson

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