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Reviews > Water Treatment > Ultraviolet > Meridian Design mUV Treatment Device > Test Report by Jamie DeBenedetto
The mUV (pronounced "move") by Meridian Design, Inc. is a hand-held, floatable, water treatment device that utilizes ultraviolet light to destroy unwanted pathogens in water. According to Meridian Design, Inc. UV-C light is "highly effective" against Bacteria, which includes Cholera, Shigella, E. Coli, Salmonella, and Trachoma; Protozoa like Giardia, Entamoebic, Dysentery, and Cryptosporidium; and Viruses including Hepatitis, Rotavirus, Norovirus, and Enterovirus. The unit only requires 75 seconds per cleaning cycle if less than one liter (34 fl oz) of clear water is being treated and it's above 40 F (5 C). Colder or murky water should be prefiltered and treated longer for an effective cleaning. To conduct a cleaning cycle the UV-C section of the unit needs to be inserted into the container of water and agitated for the duration of the treatment. The entire unit can be dropped into the water but the manufacturer says this is not the most effective way to clean the water. Beyond water treatment, the mUV also comes with a separate white LED lantern mode. The lantern mode is self timed and will run for 13 minutes before shutting itself off. The LED bulb is also used as a way to communicate to the user when the UV-C will start, when it is finished the water treatment cycle and when it is charging. The entire unit works off of a rechargeable Li-ion battery that can be recharged in the field using any single cell battery or via a solar charger (sold separately). (Charging on a D-cell pictured above.) Two small recharge wires, one positive and one negative, are housed inside the head of the device and can be retrieved by unscrewing the top screw cover. The ends of the wires are magnetic so they stick to the metal screw cover and come out as it is removed. Due to the self contained nature of the mUV accessing the recharge wires is really the only aspect of the device the user can address in the field. None of the other parts are accessible or replaceable by the user.
The mUV arrived on Thursday May 10th, 2007 in, as far as I can tell, perfect working order. The UV-C portion of the unit functions properly as does the LED feature. Included with the water treatment device were the user's manual, the tube cover with stretchy retention lead and a small nylon mesh bag that curiously did not fully fit the mUV. I found out after reading the user's guide that this little stuff sack is the prefilter. The user's guide was extremely helpful and answered just about all my questions other than the MSRP for the unit.
As of this writing the mUV is a very new product for Meridian Design, Inc. and as such they do not have any information about the device on their website. Backpackgeartest.org was sent a pdf file of the preliminary sales brochure to share with potential testers, however, so I did have a little sneak peak of the unit before it was shipped to me. The brochure had a picture and some basic details regarding the mUV's features and charging options. Given that limited information the mUV was what I was expecting, although it is much more interesting now that I can hold it.
I'm excited to start using the mUV. I already like how compact and light it is and those points alone are worth giving it a chance to impress me further with its quick water treatment abilities. Clearly much engineering genius went into its design, which is evident in how simple it is to use. The operation procedure is basically, remove the tube cover, turn on the light via a little button on the head, wait for the UV-C to start up, place it in the water and agitate for 75 seconds, return the tube cover and finally, drink the water. The mUV even shuts itself off when the cycle is complete. Whether or not it's really going to be that simple in the outdoors I don't know. It seems too good to be true but I'll have more data to go by once I get into the field with it a few times. I don't want to go as far as saying it is idiot proof, that will no doubt spell disaster on my first field test, but it looks very promising as something that can quickly do the job of making my water safe without too much fuss.
The only two concerns I have at this time are regarding the unit's inability to be repaired in the field and how well it will be able to treat water that is not perfectly clear. I will likely carry some chemical water purification tablets as a back up until I get more time with the mUV.
While playing with, or rather, acquainting myself with the unit at home I discovered it is difficult to see the LED light blinking, or pipping as the manufacturer calls it, when charging the device in direct sunlight. I don't think this will be a big concern as I'm sure I can easily find shade or a darker corner of the woods to set the mUV while it's charging if that becomes necessary while in the field.
I also experimented with a few different bottle types I had around the house. The picture to the right shows the mUV next to a 20 oz (591 ml) cycling style bottle, a standard 32 oz (0.95 L) Nalgene bottle and a 32 oz (0.95 L) collapsible bottle. The device easily fits fully into the wider mouthed cycling and Nalgene bottles but would not go far enough into the collapsible bottle to render a sufficient cleaning. (Pictured below) The larger mouth bottles worked okay but they too had their drawbacks. The mouth of the bottle, while large enough to fit the whole mUV into, isn't large enough to accommodate my fingers while I held the unit in the water and stirred. I found dangling it from the tube cover worked much better. I'm looking forward to trying it with other bottle sizes and with my water bladder as well.
This is the second of three reports; all opinions and observations in this section have been gathered after two months of using this piece of gear.
The Meridian Design mUV has been easy to transport and easy to use. It's small enough to carry in a pocket but for safety I prefer to keep it in my pack. The water I have treated has been a mix of clear to churned up and muddy but with the help of the pre-filter and a bandana I had decent results. The treated water tastes and smells similar to tap water. I have used it with 24 fl oz (0.71 L) and 32 fl oz (0.95 L) recycled plastic water bottles with the 24 fl oz (0.71 L) proving to be the most compatible to the UV tube's diameter.
Outing #1 - Two days of backpacking on a section of the Arizona Trail near Flagstaff, Arizona; elevation around 6,800 ft (2,070 m). This trail had questionable water availability but I carried the mUV as an option just in case we found a supply along the route. Unfortunately, the few sources we encountered were designated only for critters so I did not get a chance to give the little mUV its inaugural break in. I did, however, get a chance to see how it would travel in my pack. The mUV is pretty small so it was easy to find a place to store it. I was worried about how delicate it might be so I wrapped it in one of my bandanas and stored it in the top pocket of my pack where I felt it was least likely to get banged around but was still easy to access if we found water. This worked fine, it was safe and sound as far as I could tell.
Outing #2 - Day hike/canyoneering in Tonto Creek Canyon south of Payson, Arizona; elevation about 3,000 ft (900 m). The water where I chose to fill up was running nicely and quite clear. My best guess of water's temperature is between 65 and 70 F (C). This is based on a reading from my cheepy thermometer. I only needed to treat one bottle on this trip because my hiking companions were a bit skeptical about the UV-C technology and would not allow me to treat their water too.
The mUV was easy to use. It fit perfectly in the used 24 fl oz (0.71 L) Arrowhead water bottle I brought with me, in fact it fit so tightly I was able to turn the bottle upside down and sideways while agitating the water without leakage. As it turns out this was very important. I will discuss why in the Outing #3 section of this report. Despite the clarity of the water I decided to use the pre-filter, mainly because I'm not a fan of chunky water and I wanted to see how well it worked. I placed the filter, which is basically a little mesh ditty bag, over the bottle opening then cinched the draw string tight. I had to hold it on during filling but it seemed to work fine, that is to say I didn't notice a high number of "floaties" in the container afterward. The whole process took less than 3 minutes including getting everything out of my pack. The end result was water that smelled and tasted nearly the same as the tap water in my house.
Outing #3 - Day hike along a forest road in the Coconino National Forest, NW of Payson, Arizona; elevation about 7,000 ft (2,130 m). On a very rainy Saturday I headed out with my little dog Dottie in search of a trail I read about that supposedly leads into a canyon and to a very pretty spring. Perfect for testing the mUV I thought so I brought it along. Long story short, we did find the canyon but not the trail so Dottie and I wandered the woods instead and happened upon a livestock tank of sorts. It was mainly filled with rain water from the recent daily storms we've been getting and the water didn't look too bad. I filled a 32 oz (0.95 L) wide-mouth Aquafina bottle I had with me and stuck in the mUV. The opening on this bottle is too big for the mUV to completely seal and too small for the device to be dropped into, this created a problem. I agitated the water by moving the mUV back and forth and also by slightly swirling and shaking the bottle itself. Without a cover or seal over the opening water was splashing out. With about twenty-five seconds left in the purification cycle the water level was too low to cover the UV tip. The mUV itself performed fine but the bottle choice was not a good one.
Outing #4 - Day hike along West Clear Creek near Camp Verde, Arizona; elevation 3,500 ft (1,070 m). Like the previous hike we had rainy conditions on this trail too. The creek was running very muddy and wasn't the most ideal for testing but after a little pre-filtering with the ditty bag and my bandana it cleared up a bit. Just in case, I ran the UV cycle twice. I went back to using the 24 fl oz (0.71 L) bottle since this seemed to work best and was all I had with me. The picture to the right shows the mUV inserted into this bottle.
Instead of carrying the mUV in my pack this time, I carried it in the cargo pocket on my shorts. I wanted to see if it was small enough to be carried there without bugging me. It rode fine there but in retrospect I wouldn't carry it this way for long periods. It's a little bulky and while it didn't annoy me while walking I would worry about breaking it if I fell or bumped into something along the trail.
After this use I have now run the mUV through the filtration cycle a total of eight times on a single D-Cell battery charge, which I did back in May a few days after receiving the unit. The manufacturer's estimated number of uses per charge is sixteen so I'm about halfway. I will intentionally not charge the unit again so I can test this claim. Moreover, I would like the next charge to be in the field so I can see how practical the process is and how well it works using one of the AA batteries I carry as spares for my camera.
This concludes my Field Report. My Long Term Report will be forthcoming in approximately two months. Please check back then for my final thoughts regarding this piece of gear.
This is the third and final report in this test series; all opinions and observations in this section have been gathered after four months of using this piece of gear.
During the last two months of testing I used the Meridian Design mUV on a couple more day hikes, on two night hikes (for the LED option) and while on a two day women's outdoor retreat. All of these outings took place in either Flagstaff or Prescott, AZ. The water was from either ponds or stock tanks and while I'm not sure of exact temperatures the water was definitely not below the suggested manufacturer range. Air temperatures were in the mid to upper 80's (29 to 31 C) with the elevation at either 7,500 ft (2,300 m) or 5,200 ft (1,600 m) respectively.
The Meridian Design mUV continues to be simple to use and convenient to carry. I'm impressed with how long it runs on one charge. Up to the end of my field report I had very good results using the mUV to purify one bottle of up to 32 fl oz (0.95 L) at a time. During these cycles the mUV was run only once for the seventy-five second cycle then shut off and returned to my pack. The one exception was at West Clear Creek where I ran the cycle twice because the water was muddy. Not long after my field report was written I had the opportunity to treat multiple bottles of water in the same sitting. During this test I was mainly watching to see if the mUV would start to heat up after several consecutive cycles, which it did not. After cycle number two the mUV stopped working. The LED would come on but the UV cycle would not run. I let the device sit for about ten minutes then tried it again. It performed one more cycle then would not run again. Assuming the battery was low I tried the LED mode and shined it around for a second. It was clear the battery was the problem since the light was much dimmer than it had been. I decided a recharged was in order so I set it up with one of the AA batteries I normally carry as a spare for my camera and left it to charge overnight.
In the morning before heading out I tried the unit again and eureka! It worked perfectly cycle after cycle, one right after the other. I ran seven continuous cycles with only a few seconds down time in between to see if the unit would shut off again or get heated. It did not. The good news is, I used the unit eleven times before needing the second charge and that is pretty close to the manufacturers suggested number of cleaning cycles per charge.
Battery Life and Charging
As mentioned above I was able to get eleven cycles out of the mUV and at least three and a half hours of LED light before the unit needed another charge. The first time I charged the unit was right after it arrived way back in May so the mUV has kept its charge for about four months. For the second charge I went with a AA because that's what I had with me. Both times were very simple and took less than thirty seconds to set-up. I think the mUV's ability to charge off of many different battery types is a brilliant idea and makes charging in the field wonderfully convenient.
I have used the mUV's LED function several times for short bursts around camp and my home. I also used it on two night hikes of about an hour and a half each night. When the battery was fully charged the light was definitely bright enough to use for night hiking. Around camp it was good enough that I left my headlamp at home during a two day trip to Prescott.
The only feature I didn't like was the automatic shut off, which wasn't an issue while around camp but was a little annoying on the hikes. In all fairness I assume night hiking is not really the manufacturer's intended purpose for the LED function.
Wanting to give the mUV a diverse test I tried to experiment with as many container types as I own. The easiest containers where the ones that either snugly fit the mUV so the bottle could easily be agitated without water spilling out OR containers with large enough openings so the mUV could be dropped completely into the water. I also found the device worked well with my beer can pot.
The size and convenience can't be beat
It's difficult to find something I don't like about the Meridian Design mUV since by far it is the easiest water treatment device I have used and that includes chemical treatment. Honestly, only two things come to mind that are negative aspects of this device. The LED's automatic shut off function and the unit's lowered effectiveness in murky or colder water. The latter issues are not unique to the mUV but in my opinion make it difficult to completely trust the mUV as my ONLY source of purification while in the backcountry.
This concludes my involvement in this test series. Thank you Meridian Design and Backpackgeartest.org for the opportunity to share my experiences with other outdoor enthusiasts.
- Jamie J. DeBenedetto
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