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SteriPEN Opti Review

The SteriPEN UV wands have been through several generations of development, reaching a very satisfactory state with this SteriPEN Opti unit.


Overall Rating: Recommended

The previous model, the SteriPEN Adventurer, received a Recommended rating even though it had a couple of small deficiencies. This SteriPEN Opti unit removes several of those deficiencies and should get a higher rating, but the heavy current drain needed by the UV lamp used keeps it just below Highly Recommended.

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by Roger Caffin |

SteriPEN Opti Review - 1
The SteriPEN Adventurer Opti.

There are many ways used to ensure water is safe to drink. The principle ones are boiling, chemical treatment, filtration and UV irradiation. Boiling uses lots of fuel and gives you very hot water; chemicals usually leave a nasty taste and can takes ages to work, while not managing to hit all protozoa; filtration is faster but quite heavy, and (with one expensive exception) is not able to deal with viruses. UV treatment manages to deal with all biological nasties, uses no chemicals, and is fast. The SteriPEN UV wands have been through several generations of development, reaching a very satisfactory state with this SteriPEN Opti unit.

Technical Details

It would seem from comparing the outside of the SteriPEN Opti and the SteriPEN Adventurer that much of the Opti is the same. So It may be worth while reading our in depth Review of the Adventurer first. Here we will focus mainly on the changes (hopefully improvements) brought to us with the Opti.

To use the Opti all you have to do is uncap the UV lamp, press the button (once for 1 L, twice for 0.5 L), wait until the white LED starts to flash, then insert the lamp end into the water. This is illustrated in the second photo, where I tried, fairly unsuccessfully, to capture the illumination of the white LED. Stir gently for 90 seconds (for 1 L) until the UV lamp goes out and the white LED stops flashing, and you are done. In point of fact, this is also how you use the Adventurer, so one might ask where are the upgrades? Well, there are several.

First of all, many of the older Adventurer units had a rather high 'off-state' current drain, of about 600 micro-amps. This meant that storing the unit with the batteries in place for a few weeks could make a bit of a dent in the battery capacity. It was not unknown for people to go to use their Adventurer during a trip only to find that the batteries were flat. It turns out (according to Hydro-Photon, the makers), that the 'off-state' current drain was never meant to be anywhere near that high: it should have been only a tenth of that.

Smart users took to removing the batteries from the Adventurer while it was not in use, and only inserting them briefly when they needed to treat water. Well, that worked, but it was a bit of a hassle putting the batteries in and taking them out. Compounding that hassle was the flat thumbscrew used to hold the battery lid in place: it was quite awkward to remove. The hassles caused by the flat thumbscrew even led to an MYOG Thumbscrew article being published!

SteriPEN Opti Review - 2
SteriPEN Adventurer Opti in use.

The circuitry inside the Opti has been upgraded to have an 'off-state' current drain of only about 60 micro-amps. This is low enough that you can afford to put the batteries in at the start of a trip and leave them there for the duration. Believe me, this simple change makes the Opti so much easier to use in the field! In addition, the old black protective cap over the UV lamp was always hard to remove. I went so far as to slightly machine the detents on the black cap to make it easier to remove. Well, the clear plastic cap on the Opti has modified detents, such that it is now much easier to remove the cap. It does not fall off by any means, but it does come off smoothly.

The third obvious difference is in the mandatory water sensing system. When using a UV system like this there must be a safety circuit to turn the UV lamp off if it is removed from the water - otherwise all sorts of damage could be done to your eyes for instance. The older Adventurer uses a conductivity sensor with little metal plates on either side of the housing near the lamp. There have been reports of people having problems with the sensor, although I have never experienced any myself. Well, the conductivity sensor has been replaced in the Opti by an optical sensor: a flashing white LED. When the LED is immersed in water, the back-scatter of light is altered and this change is detected internally. The system works very smoothly.

On a minor technical point: the Opti comes with a small plastic battery isolating strip under the battery lid. This actually fits rather neatly into the lid. I preserved this when I took it out, so I could re-use it after the trip. It is very convenient as it means I can store the batteries in the unit.

It may be worth noting that the UV treatment works just the same no matter what the temperature of the water - unlike the huge slow-down you get with chemicals. It does help to keep the batteries above freezing, but this is not hard. Once in use the batteries do get warm.

You will find that the marketing literature mentions that if you press the on-switch for a few seconds the white LED will act as a small torch. True, but not high on my list of essential features. I gather that there was a little spare room in the ROM space of the microprocessor - so they added a feature...

Field Testing

I have used the SteriPEN Adventurer for a number of years, including a two-month trip through Switzerland in 2009, not to mention many shorter trips in Australia. I have been quite happy with the performance, although the battery business was always a slight hassle.

SteriPEN Opti Review - 3
Camp on soft grass under snow gums.

I took the Opti on a nine-day high speed trip across the Australian Alps in March 2010, just a few days after I received it. The difference in ease of use was remarkable! In comparison with the Adventurer, the Opti was a dream to use. I would pour a bottle of water into my cooking pot, whip the Opti out of its (MYOG silnylon) carry bag, flip the cap off, push the button, insert into water and stir. It was just so easy.

The supplied set of two primary batteries (ie not rechargeable) lasted the nine days very easily. I would have treated a bottle or two of water most nights. (The rest of our water got boiled as part of our cooking.) The batteries are not dead yet by any means - they should last for quite a few more trips. The company suggests that a set of good-quality CR123 batteries could handle up to 50 L, so that is consistent.


Manufacturer Hydro-photon, USA
Web Site
Model Opti or Adventurer Opti
Size 160 x 40 x 23 mm (6.2 x 1.5 x 0.9 in)
Weight (quoted) 103 g (3.6 oz) with supplied batteries
Weight (measured) 101 g (3.6 oz) with supplied batteries
MSRP Not quoted, but about US$100 in some large stores

What’s Good

  • Effective against all bugs (independent test lab results)
  • Lightweight (well, compared to a filter)
  • Very easy to use
  • Immediate results
  • No chemicals, no taste

What’s Not So Good

  • Battery consumption is significant
  • No effect on industrial/agricultural chemicals

Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.


"SteriPEN Opti Review," by Roger Caffin. (ISSN 1537-0364)., 2010-10-05 00:00:00-06.


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SteriPEN Opti Review
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Addie Bedford
(addiebedford) - MLife

Locale: Montana
SteriPEN Opti Review on 10/05/2010 15:20:59 MDT Print View

Companion forum thread to:

SteriPEN Opti Review

George Matthews
(gmatthews) - MLife
Re: SteriPEN Opti Review on 10/05/2010 18:30:55 MDT Print View

Nice review.

Good shot of light at work.

Kathy A Handyside
(earlymusicus) - M

Locale: Southeastern Michigan
Re: SteriPEN Opti Review" on 10/05/2010 20:08:18 MDT Print View

Very interesting review! I've often wondered how the SteriPEN would work. I am on thyroid medication and so I can't use iodine for purifying water, so I have to use chlorine dioxide or a filter (or both). The SteriPEN seems much more convenient and faster to use than ClO2. Thanks for the information! Cool photo of the SteriPEN at work, BTW!

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: SteriPEN Opti Review on 10/05/2010 20:18:19 MDT Print View

Hi George

> Good shot of light at work.
Thanks, but it took a sequence of 5 shots in a bracket to get the one I wanted!


Nick Klockenga

Locale: Chicago Area
Which filter is it? on 10/05/2010 20:58:10 MDT Print View

Just curious.

> filtration is faster but quite heavy, and (with one expensive exception) is not able to deal with viruses

Which filter is the 'expensive exception' ?

Great review, simple, to the point, just what I wanted to know.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Which filter is it? on 10/05/2010 22:05:18 MDT Print View

A pump filter that can handle virus? I would say the First Need Purifier. Not the lightest or most compact, but this is the "do it all" option -- fast and easy to use too -- and reasonably light.

Edited by ben2world on 10/05/2010 22:06:58 MDT.

Roman Vazhnov
(joar) - F
Re: SteriPEN Opti Review on 10/06/2010 01:22:47 MDT Print View

Is there some lightweight filter that can be added to Steripen to deal with industrial/agricultural chemicals?

Edited by joar on 10/06/2010 02:08:14 MDT.

Robin Evans
( - MLife
SteriPen Opti Review on 10/06/2010 01:42:42 MDT Print View

Bottle filtration units can be very light:

The Super Delios is only 58g, yet filters most nasties:

If you want to filter viruses as well the Travel Tap is 158g:

I can't understand why anyone wants to use anything else. These systems are light, reliable, require no power and fool proof. They are also very cheap over the life of the product.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: SteriPEN Opti Review on 10/06/2010 01:57:06 MDT Print View

> Is there some lightweight filter that can be added to Steripen to deal with
>industrial/agricultural chemicals?

Good question. You would need a fairly good activated carbon filter at least. That is not hard to create of course. In general we dodge those situations, but this is not always an option.


Dan Lazarowski
(chronon) - MLife
Wigglers on 10/06/2010 03:52:05 MDT Print View

I've heard that, although it neutralizes bacteria and viruses, that there can still be (harmless) live larva and other small swimming things in the water after treatment.

Does anyone know if that's true?

Michael Davis
(mad777) - F

Locale: South Florida
Re: "SteriPEN Opti Review" on 10/06/2010 04:55:11 MDT Print View

I have always loved the concept of UV treatment and so I purchased the Steripen Adventurer. However, after the thing stopped working for no apparent reason, I have gone back to gravity filter with tablet backup. There is simply less to go wrong and therefore more reliable.

I'll wait a year to see how long these last, but right now, I'm pretty ticked at the Steripen folks for sucking $100 out of my pocket for nothing in return.

bob ferrari
Steri pen on 10/06/2010 06:52:56 MDT Print View

I took a steri pen to Kyrgyzstan in 2005. It stopped working - just stopped - the 2nd time we went to use it. I don't think I'll ever trust one again.

Chris Benson
(roguenode) - F

Locale: Boulder
RE: Optii on 10/06/2010 07:24:11 MDT Print View

Nice tip regarding the battery isolating strip. I also found the cap on the older adventurer troublesome to remove.

I know this wasn't a direct comparison, but I'd be interested in seeing a head-to-head comparison on number cycles each gets from a fresh battery.

Keith Selbo
(herman666) - F - M

Locale: Northern Virginia
chemicals on 10/06/2010 07:30:16 MDT Print View

"Is there some lightweight filter that can be added to Steripen to deal with industrial/agricultural chemicals?"

Yes, the Katadyn Carbon Cartridge (REI $14.95) will remove many chemicals. It definitely removes the chlorine I add to my water to kill viruses before I filter it. Here's my setup. The black filter is a Sawyer bacterial filter, the grey filter is the Katadyn charcoal filter. One end screws onto my a Platypus "dirty" reservoir, the other snaps into my hydration bladder.

sawyer and katadyn combination

As Roger said, it's heavier than a Steripen but I leave my steripen at home in favor my always reliable and labor saving filtration system. All my hiking partners have made similar setups to mine after one or two trips with me. The gravity filter does all the work while you relax or tend to other chores. It only takes a few minutes and has the added benefit of removing most chemicals.

Edited by herman666 on 10/06/2010 07:47:17 MDT.

John S.
(jshann) - F
Re: SteriPEN Opti Review on 10/06/2010 08:12:18 MDT Print View

The opening paragraph gives only the pros of UV and only the negatives of boiling, filtration and chemicals.

UV treatment cons-
1. must carry backup
2. uses batteries
3. must protect the product from damage
4. not the lightest solution
5. must use heavier water container with wide mouth opening
6. must use described procedure (agitation/stirring) to properly treat water
7. best used only above 32 degrees F
8. device not waterproof
9. must use extra treatment in murky water
10. contains mercury

Edited by jshann on 10/06/2010 08:53:37 MDT.

Dean F.
(acrosome) - MLife

Locale: Back in the Front Range
anti-viral water filter on 10/06/2010 08:20:03 MDT Print View

Speaking of Sawyer...

Sawyer makes an 0.02 micron filter that is rated against viruses. So, I guess all I'm saying is that there is more than one filter that will remove viruses.

Why does Sawyer get no love? :o)

I mean, seriously, everyone should be using these things.

That said, I've been dying for an excuse to try a UV treatment system. I guess I'm holding out for UV LEDs.

Edited by acrosome on 10/06/2010 08:23:15 MDT.

Mark Roberts
(redwedge) - MLife

Locale: Lapland
steri pens on 10/06/2010 10:05:45 MDT Print View

I don't own one, but my experience of other people who have travelled with me with on is that in each case they malfunctioned after a day or two of use, either through a fault in the unit or battery problems.

I'll stick with my Sawyer filter (which those with a broken Steripen ended up using also). I just think that anything relying on electronics and batteries is too unreliable for such a vital task.

Rick Dreher
(halfturbo) - MLife

Locale: Northernish California
Re: Wigglers on 10/06/2010 10:40:43 MDT Print View

Hi Daniel,

I briefly addressed this in my BGT review of the Meridian Design mUV.

Based on five or so years' experience with UV, it's preferable to use a prefilter of some sort before treating, at least one fine enough to keep out multi-celled critters. This is pretty easy to do.



Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Reliability on 10/06/2010 10:43:45 MDT Print View

Regarding Filters -

Most of the time they work, and continue to work, as advertised. But on my last trip, pumping "optically clear" water, the Hiker Pro gave it up. There was no forewarning.

On Day 4 it just became incredibly hard to pump. I was on a 5 day hike, but if it had been a 10 day hike it would have been a real struggle to pump water. Including this trip, we had run less than 50 gallons through the filter. (It is rated for a nominal 200 gallons.)

I called Katadyn customer service and they said "Yep - It Happens". Apparently there both sediments and algae that are not "visible" but readily clog the filter.

I have used a Hike Pro for years and years and this was a first.

Much as I dislike it, I'll now be taking something as a backup, "just in case".

Evan McCarthy
(evanrussia) - MLife

Locale: Mid-Atlantic
Reliable enough! on 10/06/2010 10:52:06 MDT Print View

I've used versions of the SteriPEN for years without any malfunction. You need to sleep with it/stick it in your coat pocket during colder periods, but other than that I love the ease and speed of using it. I bring a bandana and keep whatever cup/bowl container I naturally use for the outing near the outside of the bag so I can scoop from a stream, strain through the bandana (also dual use), and have treated water a couple minutes later. The Nalgene canteen or normal one liter gatorade bottle work great for water storage.