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Steripen The Magic Flashlight

Reviewing: Steripen Adventurer  |  Rating:
Joan Young By Joan Young on
Badge: Editor | Level: 34 | Outdoors & Recreation Expertise:
Image for Steripen- The Magic Flashlight

We recently switched from a filter (see Sweetwater Guardian) to the UV light Steripen for water purification while hiking. It is really easy to use, but takes another level of trust to feel confident about it.

The Steripen is a small, handheld device to purify water in the field for backpacking, or even more serious expeditions. It uses the reliable technology of sending ultra-violet light through the water which kills microbes.

There are various models, but the one we chose is named the Adventurer. It is a small glass wand, enclosed in a hard rubber casing, and powered by a battery. We had some reservations about the glass wand, but we’ve been careful and it hasn’t broken.

It can treat either a quart of water at a time, or a half-quart (a pint). You press the switch on the side and an indicator light blinks (hold the button different lengths of time for the amount of water you want to treat). Then you immerse the wand in the water till contacts on the sides complete an electrical circuit and stir. A light inside the wand will begin to glow. Continue stirring until the light goes out, which takes 1.5 minutes for a quart. If the indicator light turns green after the wand stops glowing the water is safe. If the indicator light is red, you need to repeat the treatment.

You do have to use a container that has a wide enough mouth to accommodate the Steripen and give you room to stir. We thought we might use a quart Nalgene Bottle, but I didn’t think the mouth was really large enough, and although the bottle was translucent it was hard to tell when the wand was glowing through its colored sides. Instead I went to the grocery store and found a clear plastic, wide-mouth Miracle Whip jar. This turned out to be really perfect. We collected the “raw” water in this jar, treated it and then poured it into the containers we use to drink from. Afterwards, the Steripen, a cloth to dry it off, and a few coffee filters all fit inside the Miracle Whip Jar, providing further protection. You can treat water in a metal pan, so you don’t have to have a plastic jar if you don’t want.

The Steripen comes with a soft neoprene case in addition to the rather hard snap-off rubber tip protector.

It seems so silly to sit on a rock or log and stir a jar of water with a glowing light! We nicknamed it the “Magic Flashlight.” But for ease of use it’s sure hard to beat!

Here are the drawbacks:

It is not a filter of any kind. If the water has suspended particulate matter it will still have it after treatment. In other words, cloudy or muddy water will still be cloudy or muddy. We carry coffee filters to pre-filter if the water doesn’t look clear! It’s the various particulates that give water a “wild” taste.

It takes batteries, and not a standard size. It uses two CR 123, which are shorter and fatter than a AA battery. These are also pretty expensive, and didn’t seem to last as long as I thought they should. We treated all the water for four people for five days with one set of batteries, but it died on the third quart after that. So if you are on a long trip, be sure you have enough batteries, which of course add extra weight.

It requires a level of trust in technology that may be difficult for some people. At least with a filter you have the sense that you are doing something... moving water through some medium that removes “stuff.” With the Steripen it doesn’t really feel like anything is happening.

The tip of the hard case snaps off with some difficulty. I think we are just a little extra nervous about that glass wand, but it seems like it would be all too easy to snap it against a rock and break the wand. Of course even with a filter something might break. In any case the final back-up plan is always to boil your water before using.

Here are the real positives:

It is very compact and lightweight. With the neoprene case and batteries it weighs just 4.6 ounces. With everything we added, its own cleaning cloth, coffee filters, and the Miracle Whip jar the total package weighs 8.5 ounces. This is about half the weight of the entire water filtering package we used to carry. Shaving ounces off the load is really important to backpackers!

Ultra-violet light treatment is known to be very effective in killing microbes. You don’t have to worry about whether the filter is still catching the small guys. It would be used more for municipal water supplies, but it’s difficult to treat large quantities of water because the UV light can’t penetrate a great depth of water.


We have been very happy with the Steripen. We treated enough water daily for four people for two weeks, and it didn’t take any more time than filtering that amount of water would have required. For one or two people it seems really quick. Just be sure you have extra batteries. On one solo hike I had to boil water for three days because the batteries went dead!