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Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW

Treat your water using this robust, 3.9-ounce, ultraviolet light based, water purifier.

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by Ken Knight | 2006-09-19 03:00:00-06

Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW


We all have to deal with making our drinking water safe during backcountry trips. Until recently, we could choose to filter, chemically treat, or boil our water to ensure with confidence that it was safe. Each method has its advantages and disadvantages, its adherents and detractors. At the 2005 Outdoor Retailer Winter Market, Meridian Technologies introduced the AquaStar UV Purifier. Meridian has since improved the product, releasing the AquaStar Plus at the 2005 Outdoor Retailer Summer Market. They have continued to make improvements to the product to become the robust ultraviolet light water purifier we review here. If you do not like the hassle of working with chemicals or a standard pump filter (to say nothing of toting the weight of the average pump filter), then perhaps the 3.9-ounce (110-grams), purifier only, AquaStar Plus deserves a closer look.

What’s Good

  • Fast. Purifies 1 liter of water in 80 seconds.
  • Built-in lantern provides ample light for in-camp use.
  • Does not affect the taste of the water.

What’s Not So Good

  • Uses non-rechargeable CR123 batteries.
  • Does not screw completely tight to Nalgene Canteens which can result in minor leakage when canteens are upended.
  • Severely affected by moderately cold air and water temperatures.



2006 AquaStar Plus UV Water Purifier


Measured weight 8.2 oz (232 g); manufacturer's specification 8.5 oz (240 g) for UV unit with batteries attached to the supplied polycarbonate 1L bottle.
Measured weight of bottle 4.2 oz (120 g)
Measured weight of UV-C Purifier without batteries 2.6 oz (74 g). Measured weight of batteries 1.1 oz (34 g). Measured weight of pre-filter 0.1 oz (4 g).

  Battery Type
and Lifetime

Two x Type CR123 batteries (3 volt photo batteries)
Approximately 60 purifications cycles per set of batteries.


Treats one (1) liter of water in 80 seconds
Lantern function uses three white 5 mm LEDs built into the cap and runs for 15 minutes before auto-shutoff (30 minutes of lamp use is equivalent to one water treatment cycle).
UV-C lamp estimated to last 2,000 hours.




AquaStar Plus operation could not be simpler. Fill your water bottle, screw the AquaStar Plus on tight, push and hold the button for a moment until the UV emitter activates, and that is all there is to it. If the water is turbid or you want to be extra careful, swirl the water around some during the 80 seconds the ultraviolet light is on. To limit the amount of detritus that enters your water when you fill your bottle, simply cover the bottle’s mouth with the provided no-see-um mesh prefilter to block larger particles and debris. Once a water treatment cycle is complete, a green light in the head of the purifier will flash for 10 seconds. Should a purification cycle terminate before the required 80 seconds have elapsed a red light will flash instead, indicating failure to complete.

The cleverly designed prefilter/strainer is a piece of fabric with a drawcord. To use, secure the pre-filter to the top of your water bottle, tighten the drawcord to ensure a snug fit, and then dip your bottle into the water source. The strainer acts like a coffee filter, straining out 200-micron and larger particles from the water. Not as fine as a paper filter, its purpose is nevertheless to remove the larger debris that could block the light from the UV emitter and float unpleasantly in your drinking water. I used the pre-filter in fairly cloudy source water and found it does a nice job of visually clearing the water.

Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW - 1

Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW - 2

The fabric pre-filter traps 200-micron and larger particles. Its purpose is to remove debris that could impair the Aquastar's functionality.

Built into the AquaStar Plus’ solid plastic head is a lantern made of three white LEDs. The lantern is turned on by quickly clicking the power button twice. Once on, the light remains lit for 15 minutes, then shuts off automatically to preserve the batteries. According to the manufacturer, running the light for 30 minutes drains the batteries the equivalent of one complete treatment cycle. The lantern casts non-directional white light that is more than enough to do all manner of camp chores, or even read a book in your shelter. I found that leaving the bottle full of water improved the lantern's functionality.

Changing the batteries is a simple task. The thumbscrews on top of the AquaStar Plus can be loosened while wearing gloves but be careful, it is easy to lose a screw. Fortunately the unit works just fine with one locking screw. In warm weather, the batteries power the unit as claimed. However, when the temperature drops the ultraviolet light refuses to run through a complete cycle. With the return of warmer ambient air and/or water temperatures, the unit works normally again.

Meridian Designs claim that the AquaStar Plus can purify 60 liters of water on a fresh set of CR123 batteries. I have found this claim to be about right under warm air and water conditions, but cooler temperatures degrade performance. A more reliable number seems to be about 50 liters per set of batteries. With some careful shopping, you can greatly reduce your cost per liter of operation, as CR123 prices vary wildly.

The AquaStar Plus ships with a polycarbonate 1-liter bottle that has directions and appropriate warnings printed on its side. The combined weight of these two components is 7.9 ounces. The unit can be used with wide-mouth Nalgene Canteens, saving several ounces. The only minor problem with this is that you need to exercise some care screwing the purifier on to the Nalgene Canteen, since the fit is not quite as secure as the standard cap. If you keep your water bottle upright, the worst you will likely see is a very slow accumulation of water around the threads. If I ever lost water during the course of a typical backpacking day, it was minimal.

Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW - 3
The AquaStar Plus in its polycarbonate bottle. A water treatment cycle is in progress.

Despite several weeks of use and several flights stowed in airline luggage, the AquaStar Plus has shown no signs of wear and tear. While I have no doubt that the AquaStar Plus is more vulnerable to failure than treatment chemicals, I have not taken any special care with it. The unit has ridden in an external pocket of my Gossamer Gear Mariposa on several trips and has fallen from out of that pocket onto the ground a few times (as the result of my own falls). I have no doubt that placing the AquaStar Plus inside the hard-sided confines of a polycarbonate bottle will improve overall durability, but the purifier has functioned well inside my Nalgene Canteens.

What’s Unique

The market for UV water treatment systems is still fairly new. The AquaStar Plus represents a well-thought out and implemented entry into this new arena of water treatment. In our fast-paced world of plug-and-play items, the AquaStar Plus provides almost instant gratification when it comes to treating water.

Recommendations for Improvement

Overall the AquaStar Plus is a well-designed product. It has some limitations but most are unavoidable, like the power requirements. This is not a knock against the AquaStar Plus, since all water treatment tools have limitations. One design change that would be nice to see is the use of captive screws for the battery cover.


"Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW," by Ken Knight. (ISSN 1537-0364)., 2006-09-19 03:00:00-06.


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Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW
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Cat Jasins
(CatJasins) - MLife
Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW on 09/20/2006 03:42:54 MDT Print View

Companion forum thread to:

Meridian Designs AquaStar Plus Ultraviolet Light Water Purifier REVIEW

Glen Van Peski
(gvanpeski) - F - M

Locale: San Diego
comparison of Aquastar and Steripen? on 09/20/2006 06:39:48 MDT Print View

I have friends who are pleased with the Steripen, but had bad luck with earlier models of the Aquastar. Anyone have experience with current models of both?

Kim Skaarup
(skaarup) - F

Locale: Cold, wet and windy Scandinavia
Aquastar on 09/20/2006 14:35:01 MDT Print View

Glen, what was the problem.?

I got hand of one of the first productions and it have worked perfect. Also the comsumerservice was 1.class. As Im in Europe they did by them self remember that I needed a 230 volt charger and shippede it 2 month later when it was produced.!!

I also use it at home when some one has bad stomach or something.

UV treatment is very smart.

Bill Law
(williamlaw) - M

Locale: SF Bay Area
Performance? on 09/21/2006 10:39:39 MDT Print View

Interesting that there's nothing in the performance section on how well this thing actually did in cleaning your water.

That's probably difficult to test but I have questions like: Does the wet filter saturated with contaminated water increase the likelihood of depositing pathogens on one's hands or other gear? Can it work with a 96oz Nalgene canteen, 48oz, or just the smaller ones? Does one do three cycles for 96oz? Does it remove protozoa? viruses? bacteria? What government standards does it meet?

One other thing is the business about "Severely affected by moderately cold air and water temperatures." There was no mention of that elsewhere in the review. I see on their web site that it recommends two treatments for water colder than 40 degrees Fahrenheit. But it doesn't say whether that's the water temp or the air temp.

Seems to me that the temperature thing means it is less effective on water that's 50 degrees than it is on water that's 70 degrees. What temperature(s) were treated to get the ">99.99%" effectiveness cited on their web site?

I tried to find the EPA manuals cited by the company, without success. I did find some apparent references to it that raise some issues in my mind: It is aimed at treating drinking water systems, not necessarily water free-flowing streams and lakes; and there are lots of factors that influence the effectiveness of UV.

Sorry to be so skeptical.

Bill Law
(williamlaw) - M

Locale: SF Bay Area
use with nalgeen canteens? on 09/21/2006 10:55:09 MDT Print View

I just noticed that the product literature appears to say that their bottle absorbs the UV-C, which can be harmful at certain levels.

I'm not sure use of this with other than their bottle is recommended.

Also, the user manual is way too brief for my taste. No mention of the words "cold" or "temperature" (that I could find). Which means most users where I hang out in the mountains wouldn't be getting clean water unless they read between the lines of the battery specs.

Rick Dreher
(halfturbo) - MLife

Locale: Northernish California
Re: use with nalgeen canteens? on 09/21/2006 13:49:41 MDT Print View

I'll try to respond to some of your questions, as I've used an AquaStar Plus for two seasons now and have done limited review of technical materials on UV.

There are no restrictions regarding container material for use with the AquaStar--only that treatment time be commensurate with the water volume. I'll add that container shape should be considered to keep the water within a reasonable distance from the tube (e.g., avoid very wide containers). I leave some airspace so that slow agitation creates good circulation during treatment.

I primarily use mine with either a bicycle bottle or a 48-ounce Nalgene Cantene. The supplied 1L bottle is a little bulky and heavy for me as a backpacking bottle.

Temperature limitations are based on the water temperature, not air temperature (although the electronics, if left out in freezing temps, should be warmed up first to work correctly). In my experience, the unit will work in cold water so long as the batteries are relatively fresh. If they're not, I have to warm the water first, usually inside my jacket, otherwise it won't complete a cycle. It gives a clear error code when it's not cycled completely.

As a general guideline, for very cold water, particularly suspect water, or turbid water, doubling or even tripling the cycle might be appropriate. I've not often felt the need, but always let conditions and location dictate. Staying with the best source water available is always my goal, no matter how I'm treating (or not).

UV will inactivate bacteria, viruses and cysts (including giardia and crypto). Its fast inactivation of cysts puts it ahead of chemical treatment, and its effectiveness against viruses puts it ahead of almost all filters. And of course, it doesn't affect taste.

But as with any water treatment system, UV isn't for everybody or every situation. I've developed a preference for the AquaStar in the time I've been using one, but haven't completely abandoned filters or chemical treatments either. Will also be very interested to see the new Steripen we previewed at the show!

Edited by halfturbo on 09/21/2006 17:34:18 MDT.

Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
Use with Nalgene canteens on 09/21/2006 16:22:51 MDT Print View

Rick Dreher answered the bulk of the questions already, but I'll add a bit more.

I did not attempt to use the Aquastar with very large canteens, but as Rick notes you simply need to increase the number of purification cycles to meet the water volume (e..g, 3 cycles for 3 liters).

As Rick notes the water temperature seems to play more of a role than air temperature except that air temperature does seem to affect the electronics. If you are concerned aoubt how well things are going doing an extra cycle will certainly not hurt anything.

As for pathogens on your hands when using the strainer I don't think this would be any more of an issue than you would encounter when just getting your hands wet in natural water sources. If you are concerned wash your hands afterwards.

This is not really new technology for water treatment. It is new for backcountry use, but people who have aquariams will recognize the use of UV purification as it can be found in auariams wiping out algea and the like.

I did not speak to how well the water was cleaned because it is impossible to test this without a lab. This is true for any water treatment; we have to rely upon the manufacturer claims here.

As with any treatment technology this one has limits and a proper understanding of those is important.

Benjamin Smith
(bugbomb) - F - M

Locale: South Texas
Re: Use with Nalgene canteens on 09/21/2006 16:33:48 MDT Print View

I would appreciate a look into the effectiveness of these treatment measures. I'm fine just considering this review to be a review of "what it's like using this product," but I hope that eventually BPL will perform their own tests so we don't have to take the manufacturer's claims. The editor's commitment to cutting through marketing BS has always been one of this website's strong points.


paul johnson
(pj) - F

Locale: LazyBoy in my Den - miss the forest
Re: Use with Nalgene canteens on 09/22/2006 02:25:39 MDT Print View

>>"3 cycles for 3 liters"

is this really the case? perhaps? or is dosing more like a second-order function, meaning, double the volume and quadruple the number of dosings? triple volume might require nine dosings.

can we be sure that agitation of a larger (2L or 3L) volume of water while dosing allows for a linear incremental dosing approach?

does the Mfr. agree with this volume- dosing extrapolation? if not, why not dose 1L and pour it into a larger 2L or 3L container, and then dose another 1L?

sorry, more questions than answers from me? can Mr. Knight or anyone authoritatively answer these queries?

Bill Law
(williamlaw) - M

Locale: SF Bay Area
mysteries of the aquastar on 09/22/2006 09:29:02 MDT Print View

>There are no restrictions regarding
>container material for use with the

The user manual sez: "UV-C light can cause irritation to the eyes and skin if exposed for an extended period (over 6 minutes at 1ft distance). The UV-C light is absorbed by the plastic bottle..." and "The AquaStar Plus! bottle provides 100% shielding of any UV-C light".

I wonder if that means their bottle is at all "special." Does the shielding bounce the UV back or absorb it? Does the UV escape a Nalgene canteen and thus not provide a high enough dosage to kill the pathogens? Are the UV-C levels referenced in their "efficacy" document based solely on use with their bottle, or using a variety of containers? Does the UV-C dosage vary depending on the container?

BTW, I'm not so much asking questions about the device itself as suggesting that the review should have been more, um, "inquisitive" about the pertinent performance aspects of the device. If I *was* considering using this thing to treat my water then I'd want a little more info. (NB: I hike in the Sierra where no treatment is necessary, at least according to my risk/benefit analysis, so I'm not considering it.)

And the shortcomings of the user manual should have been mentioned, regardless. Obviously, it doesn't provide nearly the information one needs to use the product effectively in the real world conditions most readers will experience. Unless said use is solely to assuage one's misplaced fears, which perhaps it is :-).

Rick Dreher
(halfturbo) - MLife

Locale: Northernish California
Re: mysteries of the aquastar on 09/22/2006 11:02:20 MDT Print View


WRT increasing dose with volume, per the owners manual (downloadable pdf on the Website) it's linear, i.e. one cycle per liter.

For me, using a larger treatment vessel is simply a workflow consideration. I find it easier and faster to treat larger volumes when collecting a gallon or more water for camp. Strictly personal preference. Likewise, when using a bottle smaller than 1L, the cycle can be halted in less than the standard time. That's what I do on the trail.


There's no reflection mechanism at work with the supplied bottle, directing UV back into the water, so any bottle material is fine. One could use metal or glass, for that matter.

IIUC the maker's warning about soft-sided containers is the lack of physical protection against breakage, not a concern about the material itself. So long as one's not storing and transporting the tube in a Cantene, there's no reason not to use one for treatment.

As to UV radiation, the only potential danger from the AS's emitter would be looking directly at the bare discharge tube. From what I've read, it's a challenge to find materials that are sufficiently transparent to the relevant UV wavelengths from which to make the lamp itself, which is why it's quartz.

I think of the warning as being along the lines of the "Do no operate heavy machinery..." sort. Hopefully, not many folks will sit in camp after dinner, gazing at the pretty blue light.

From my conversations with the AquaStar folks, I'm impressed with their relevant knowledge of the technology and the biology. As I'd expect, there's conservatism designed into the product, both in the light intensity and the treatment cycle time. Given the product's important task, it's what I'd expect.

You and I must certainly hike different parts of the Sierra, but continued good health to you!

Paul Rancuret
(viking8388) - F

Locale: North Texas
CR-123 battery on 09/22/2006 19:11:29 MDT Print View

Thanks Ken for the review.

I have just one comment to make: In your list of "What's Not So Good", you mention that the unit uses non-rechargable CR-123 batteries.

For what it's worth to all who have (or are considering) this unit, rechargable lithium CR-123 batteries are available. One possible source is Thomas Distributing (see


Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
Answers to questions on 09/23/2006 14:35:09 MDT Print View

Rick has again beat me to the answers but I'll re-affirm them.

According to the manufacturer the dosing forumla is linear.

Their is nothing special about the bottle that comes with the AS+. A hard-sided bottle will provide a bit more physical protection for the AquaStar Plus than a soft-sided one, but that is the only difference. The warning about staring into the light is thir because unless you have an opaque (too UVC) bottle the chance of doing yourself harm, though perhaps small, is real. You wouldn't stare into the sun through a magnifier or operate heavy machinery while taking new medication and this falls in that same category.

About recharable CR123 batteries. When the review was written these were not readily available and I personally have no experience with them. They do work and the manufacturer will sell you a charging kit and rechargable batteries (though I expect you can buy them elsewhere too).

Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
EPA docments on UV Disinfection on 09/23/2006 16:23:16 MDT Print View

I neglected to answer this question earlier. Some of you have already found the informatin on the website for the AquaStar Plus that includes references to the EPA document 815-D-03-007. That document has moved around a bit on the EPA site and is not immediately obvious. It can be found at Ultraviolet Dininfection Guidance Manual. Their are other doucments on the EPA site that you might find of interest, in particular, the somewhat older 815-R-99-014.

Edited by kenknight on 09/23/2006 16:39:49 MDT.

Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
User manual on 09/23/2006 16:48:59 MDT Print View

While I agree the manual is a bit terse it is strictly meant to be a user manual and not a discussion of the science behin d the product.

It does tell you how many cycles to use per liters of water and for most instances is sufficient. Would I have liked more, sure. But more can be found on the manufacturer's website. While not ideal it is not a serious flaw.

I would note that the manuals I've seen for the basic pump filters are not that detailed either. Basic instructions on use and that is as far as they go. In fact you could argue that they do not stress enough tht you must keep components separated from each other.

I am not making excuses here, merely pointing out some facts.

David Goodyear
(dmgoody) - MLife

Locale: mid-west
try the steripen's site on 10/03/2006 21:07:57 MDT Print View

I have been using the steripen and find it to satisfactory for my needs. Many of your questions can be answered at their site. They even offer the microbial studies for your review. I was still skeptical so I turned to my wife-who is a microbiologist- and she reminded me that UV light is used extensively in the lab to sterilize their working areas. OK I have to trust her after all we have been married for 22 years and if she wanted to do me in it would have been sooner.

The UV light can't hurt you through the bottle, it is even reflected back where the water meets the air.

The only limitation that I have found was if you travel in groups of 4 or more. I found that mechanical filtration was faster for the increased volume of water we needed. You do need to be careful about using turbid water. Since the filter uses light, cloudy water will not give you an adequate dose. The temperature limitations as far as I have read relate to the batteries and electronics not the water. I would suggest placing the entire unit in your coat pocket before use if the temp is low.
I found that using a nalgene bottle with a pre filter and dumping the treated water into a soft-sided canteen worked well.

I just found out about the aquastar and it is lighter than the steripen (mainly because of using button batteries-instead of AA), but I'm happy with my choice. I feel more confident after reading the extensive testing and safety features on their web-site.

I hope this helps.


Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
EPA article on UV Disinfection on 01/14/2007 15:29:08 MST Print View

The article that I noted in a prior message that discusses UVC disinfecant technology is no longer a "draft" article. As such it's URL has changed to to this link.

Roger B
(rogerb) - MLife

Locale: Here and there
Re: EPA article on UV Disinfection on 01/14/2007 16:05:52 MST Print View

Thanks Ken, lots of reading there.

I have been happy with the Aquastar and have been tempted by the steripen Adventurer, but after dropping the nalgene bottle (with aquastar attached) on to a hard surface and the aquastar still working I think I will pass on the adventurer.

Certainly UV disinfection means less water carried in the wet NE