Hydro-Photon Steri-Pen

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By now, you're probably at least familiar with the Steri-Pen, which uses ultraviolet light to purify water. Not only does it kill bacteria, including giardia and cryptosporidium, but it destroys viruses, as well. After using the product over several months, and in many environments, we were sold on the technology (none of us have fallen victim to waterborne illness). We did have concerns over its functionality in the field, but the manufacturer, Hydro-Photon, has addressed some of the issues, which we'll get to in a second.

First, we're pleased with the overall design of the Steri-Pen. With the weight and bulk of a medium-size flashlight, the 7-ounce device is easy to use and operates on two AA batteries. Consumers today love convenience, and in many respects, the Steri-Pen functions more efficiently than a traditional pump system. To operate the pen, you push a button to arm it, dip the pen in a container and stir. When the pen is dipped in water, a liquid sensor automatically turns on a lamp that emits ultraviolet light to purify the water. After stirring for less than a minute, a green light indicates that the water is purified.

The pen has a couple of great benefits. First, it won't make your water taste funny, as iodine will. Second the Steri-Pen process goes much more quickly than purifying with a pump. But our initial tests brought to light a certain problem.

When Hydro-Photon first introduced the product, it directed users to treat only 16 ounces at a time. But this proved a difficult task in the field. As most people would do, we first tried to use a standard Nalgene bottle to measure out the 16 ounces. After all, this is typically the only measuring device we carry into the backcountry. Plus, we needed to treat the water in a container before pouring it into hydration bladders. Unfortunately, the bottle mouth on the Nalgene was too small, so we couldn't lower the pen far enough to submerge the lamp and still hold the pen.

Hydro-Photon originally designed the pen for the travel market, and assumed folks would be stirring liquid in a cup. Faced with the water-bottle conundrum, the company did more tests, and realized that you could effectively purify 32 ounces of water by treating it twice. The company says its new literature points this out.

Although not a problem with the unit, you do have to remember that this thing works on batteries. While our Steri-Pen never failed in cold temperatures, freezing conditions could potentially affect the battery performance adversely. Battery life, as long as you start each trip with new batteries, is fine for most users. On one trip, we tested the pen for a solid week in the backcountry before having to change the batteries.

Our major concern is that the unit can only be used with clear water as instructed by the manual: "Steri-Pen is intended for use in clear water. Steri-Pen should not be used in discolored water or water containing particulate matter. Discolored or dirty water should be filtered until free of discoloration and particulates prior to treatment with Steri-Pen." We noticed that over the course of several trips throughout the country, we were likely to cover stretches of terrain where we were forced to treat silty water -- especially common in the south and southwest and in water from snowmelt or glacier runoff. This meant we had to take the time to let water settle or pre-filter the water -- as if we were also going to tote along a filter for those moments.

Despite a few backcountry limitations, the Steri-Pen is a useful tool, especially for travel, and it could light the way to the next evolution of water-treatment systems.

SNEWS Rating: 3.5 hands clapping (1 to 5 hands clapping possible, with 5 clapping hands representing functional and design perfection)

Suggested retail: $199

For more information: 888-826-6234 or www.hydro-photon.com

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