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  • This updated version of the Classic has a new LED display, a more ergonomic design and the ability to accept alkaline, lithium and NiMH batteries (sold separately)
  • Ultraviolet (UV-C) light rays safely sterilize clear water by destroying 99.99% of protozoa (including giardia and cryptosporidia), bacteria and even viruses
  • To purify your water, just press a button and gently agitate the water with a quick stir
  • If clear water is not available, no worries—the SteriPEN prefilter clears particulates and debris from water
  • Using the SteriPEN Prefilter: remove filter cartridge, insert Classic 3 into the PreFilter center, turn bottle upside down and gently rock back and forth to agitate
  • Prefilter fits Nalgene® and other water bottles with 63mm wide-mouth openings; pour source water through filter, and clean water enters bottle
  • SteriPEN Classic 3 Water Purifier purifies 16 fl. oz. of water (cold or warm) in less than a minute or 32 fl. oz. in a minute and a half
  • Small size fits most containers—use it in cups, mugs, water bottles and canteens
  • SteriPEN turns itself off once ultraviolet treatment is complete; can be used up to 8,000 times!
  • With 1 set of AA alkaline batteries, the Classic 3 purifies up to 50 liters of water; with 1 set of AA lithium batteries, the Classic 3 purifies up to 150 liters of water
  • Includes SteriPEN Classic 3 Water Purifier, prefilter and instruction manuals; batteries sold separately
  • Certified by the Water Quality Association to meet U.S. Environmental Protection Agency standards for microbiological water purifiers
  • SteriPEN Premium Lamp Life Pledge lets you register your purchase to receive a replacement SteriPEN after 8,000 uses; find details at


View all SteriPEN Ultraviolet Water Purifiers

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Best Use Backpacking
Filter Type Ultraviolet
Filter Medium Ultraviolet light
Removes/Destroys Protozoa, Bacteria, and Viruses
Pump Force Not applicable
Pump Strokes Per Liter Not applicable
Output 32 oz. per 90 seconds
Housing Material Not applicable
BPA Free Yes
Field Cleanable Yes
Dimensions 7.3 x 1.7 x 1.7 inches
Weight Without batteries: 3 ounces
Rated 5 out of 5 by from Great for backpacking and international travel We used the Classic 3 on a recent trip to Peru that involved travel to cities, small towns and two backpacking trips. The device was so convenient and kept us from having to purchase endless plastic bottles of water. We even used it in restaurants and on the train (as discreetly as possible). We have another, lighter model for backpacking but we like the Classic 3 for international travel because the AA batteries can be found anywhere. We used rechargeable batteries and brought a small charger, which worked great.
Date published: 2015-08-03
Rated 4 out of 5 by from This works well unless it gets wet I found this so easy to use I almost swooned! However, after 3 days the battery case got wet and that was the end of my sterilized water. The directions do say to keep the pins dry but you apparently have to be more careful of moisture than I was. Note that it was raining, that complicated the matter. So I recommend it but with the note that you better take a backup.
Date published: 2014-08-23
Rated 5 out of 5 by from Solid solution Have an earlier version of the Steripen and like it a lot PRO: + FAST: your water is ready in a minute + COMFORTABLE: you can purify the water at your cooksite or other location - no more balancing on the bank of a stream while you pump + DURABLE: no moving parts CON/ Considerations: - ELECTRIC: producing UV light with sufficient intensity to scramble microbe DNA requires a lot of "juice". I find I'm okay with fresh lithium AA batteries for several days (haven't tapped them out), but if you go alkaline, you'll need replacements. With NiMH you'll need a solar cell or other means to recharge. - UNREPAIRABLE in the bush: In theory, the glass lamp is delicate and could be cracked/ruined, but it's capped when not in use so it doesn't seem to me to be much of an exposure. I travel with a small amount of Iodine and asorbic acid (to knock out the metallic Iiodine taste after it has done it's job) as a failsafe. - VOLUME: You can treat a liter at a time. Some gravity-driven or squeeze-pressure driven systems can hold larger volumes of untreated water, but Steripen also works very quickly, so 1 liter in a minute still beats pump-action solutions. You SHOULD have a spare "dirty" water vessel (like a disposible gatorade bottle) for fetching water to pour into your bottle to treat if you want to be totally sure you don't have any untreated water on the rim/threads of your bottle.
Date published: 2014-05-31
Rated 5 out of 5 by from Stop Water Bottle Waste I have had the same Steripen for the last 7years, and it goes with me whenever I travel outside of the U.S. or just into the backwoods. I am very happy to say that I have not fallen ill while using it either, and it has been put the test in Nepal, East Africa, and Mexico. When I have friends tell me they are going abroad I tell them this is the one thing they have to buy! Stop plastic waste and drink the water.
Date published: 2015-04-07
Rated 5 out of 5 by from Best water purifying solution Fantastic product, easily the best I've used for it's purpose. The battery life has greatly exceeded my expectations (I use commonly found rechargeable NiMH). Both the pen and filter are simple to use, quick, and reliable with a wide mouth water bottle.
Date published: 2014-07-30
Rated 5 out of 5 by from Great for the Smokies I just recently bought this to replace a unit I bought more than 10 years ago and bulb life finally gave out. Glad this one has a much longer bulb life and glad to know if it fails I can get a replacement. Most of my trips are fishing, hiking, and backpacking in the Great Smoky Mountains. There the water is clear to the point that it is almost like distilled water and killing giardia is the only reason to filter. I don't use the prefilter for this reason, but love that I can just take one cheap disposable water bottle and refill and sterilize whenever I need more water. Lightweight, easy to do once you figure it out, and has proven reliable through years of heavy use
Date published: 2016-10-05
Rated 5 out of 5 by from Easy and light I have quite a bit of experience with pump and filter systems, and definitely prefer this device. It's light and much simpler and easier to use than systems with a lot of tubes and filters and pumping into some reservoir. I use only in very clear mountain water. I would be less confident with more turbid water supplies.
Date published: 2014-07-25
Rated 4 out of 5 by from Critical That Pins Are Dry It took me 4 years to really read the directions. Usage was very intermittent and frustrating until I carefully dried the two sensor pins between each use. It now works perfectly and customer service was great in trying to fix the two pens I purchased. They really didn't need fixing and it would have been better if customer service had asked me if I had carefully dried the pins before each use. Great device when used properly.
Date published: 2015-08-17
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What's the difference between Steripen Classic and Classic 3?  What does the LED window show?

Asked by: Dan the Birder
The biggest difference between the older model, Classic, and the Classic 3 is the number of liters you can treat with a set of batteries. Classic 3 has improved circuitry which allows effective use of alkaline batteries. With the Classic, only lithium batteries were recommended. With Classic 3 you can treat about 50 liters using alkaline or 150 liters using lithium. Other improvements were added - like the cap is easier to remove and the casing is more watertight. The LED indicators tell you the status of the treatment and the batteries and warn you when you have 100 treatments left (out of 8,000 treatments provided). If you register it at, they'll give you a new SteriPEN if you use all 8,000 treatments.
Answered by: J M
Date published: 2017-03-11

Looking into bike-packing, would this work for multi-day and extended trips?

Asked by: Dancinghiker
Many of bikepackers choose SteriPEN for their water purification needs because of its small size, ease of use, and fast operation. If you check out packing lists online, it's the choice they are including in their packs. SteriPEN was also recently featured in a packing list in Bikepackers Magazine. 
Answered by: SteriPEN
Date published: 2017-02-18

Can one use a SteriPen to safely sanitize a water bladder?

Asked by: jacquelineandtyler
When I travelled in South America through Quito, Peru and Chili, I used the USB rechargeable version of Steripen, and supplied water for 4 people for two months using a platypus 3 liter bladder. No-one got sick from it. It was clear, pre filtered water, and I'd run the Steripen twice while occasional swirling the water, attempting to ensure all of the water was exposedto the light. Worked great for me in this way.
Answered by: Benevolent Wind
Date published: 2017-02-10

I am going to be traveling to Mexico. I have a sore spot for "aguas" which are different flavored juice type drinks that are sold by venders. Would the steripen work for this type of drink or any drink that is more than water?

Asked by: Mlowe
​This purifier is designed to work only on water.
Answered by: REIservice
Date published: 2017-03-07

How many batteries does it take? In other words, how many in a set? If it can use AA or AAA size, how many of each? I don't think the specs state.

Asked by: Peter on the Trail
The Classic SteriPEN requires 4 AA batteries to operate.
Answered by: REIservice
Date published: 2016-11-28

How do I purify multiple, successive bottles of water? Does the Steripen need to be dried, reset or otherwise?

Asked by: KarenMG
To treat multiple bottle of water with the Classic 3 Water Purifier you do not need to dry or reset the device. Simply dip it in the next container of water, push the power button to turn the light on again and stir the water gently.
Answered by: REIservice
Date published: 2016-12-09
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