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  • Use the prefilter to provide clear water, which in turn can be purified using the SteriPEN™ Water Purifer or other purification methods
  • Prefilter screen has a square aperture equal to 17 square microns
  • Replacement cartridges available
  • Please note: Prefilter will not fit the SteriPEN Adventurer or Traveler but can still be used as a basic pre-filter


View all SteriPEN Water Filter Accessories

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Best Use Backpacking
Rated 4 out of 5 by from Very useful addition for steripen Completes the Steripen package - filters out the bigger chunks ( bark, needles, sand , mosquito larvae etc..) - great for the squeamish or those not comfortable with floaties in their water. The Steripen is MUCH easier to use (like it was hard before?) with the prefilter cap & it resolved the fears I had about lingering contamination on the rim of the treated water bottle. Hint: It took me a few tries to figure it out, but you pull up on the blue thing in the middle ( like a water bottle top)and let it vent above the water while you submerge the rest of the filter under the surface. This makes the fill rate go way up - 30 seconds or so tops. I love this thing & love my Steripen.
Date published: 2008-05-29
Rated 5 out of 5 by from ALWAYS Pre-Filter First! Off-Road Safety Academy If like me, you need to source dirty water containing lots of particulate matter ("Crud"), it is a necessity to pre-filter the water prior to applying any type of water disinfection treatment. Nobody likes "crunchy" Crud in his or her naturally sourced drinking water. Yuck! With the SteriPEN Pre-Filter, your removal of Crud is EASY. With this ingenious device, you can easily source water from a tap, lake, pond, or stream. SteriPEN's Pre-Filter also makes it incredibly easy to use your SteriPEN to disable the genetic code of all the bad Critters that can be found in wilderness water sources. Simply remove the small pre-filter from it's bottle cap and place your SteriPEN down into the water. Many models of SteriPENs will seal against the bottle top's opening. This allows you to turn the bottle upside down and shake it during UV treatment. There you have it… No Crud and complete disinfection. With SteriPEN's Pre-Filter and use of any model SteriPEN, you have a genuine water disinfection "system" that is small, convenient, and trust worthy. Review by Bob Wohlers, Owner of Off-Road Safety Academy, at
Date published: 2015-08-01
Rated 1 out of 5 by from so good it stops water from entering the bottle! I bought this to keep out floaters and swimmers (a lady's stocking works pretty well also). We often collect pot hole water in the Canyonlands and it can be full of living stuff like little shrimp and bugs. I took this prefilter out and it worked well in March on a 6 nigtht backpack. I took it back for a 8 day trip in April and it totally failed! Water would simply not flow into the bottle regardless of what I did, submerged it, half submerged it. I tried everything. I can blow through the filter from the outside in or the inside out but water won't go through it! I cleaned the filter with a soft brush and soap...still won't work. Weird and disappointing.
Date published: 2016-05-20
Rated 4 out of 5 by from Works really well! I found this product to be an essential part of using my Steripen. It took a little while for me to get used to it, but now that I have the hang of it things are a lot easier. This product fixed the problem of the threads of your bottle being contaminated. Otherwise you really need to make sure that you wipe down the threads before drinking the water. I did not find the filter to be bulky, but if you are really concerned about weight a coffee filter would do the job. I discovered that you can "store" the filter right on the bottle (took me a while to figure that out) by taking the little filter out and turning it around and then putting the lid to your Nalgene on top of the filter. (0n an empty bottle so you don't contaminate clean water). It is apparently designed to do this because it has threads on both ends of the pre-filter. I also found that if I submerged the entire pre-filter (with the air vent open) the water filled much faster than if I tried to let it pour in the sides. While backpacking during spring runoff and very muddy water flowing out of the mountains, this product was nice to have. Otherwise my water was pretty mucky and gross, albeit sanitized. The pre-filter also made the process of sterilizing the water really easy because you keep the prefilter on and just stick the Steripen right into it and turn it upside down to shake it.
Date published: 2008-07-17
Rated 2 out of 5 by from Not worth the extra ounce and a half? I hike in an area where water (if it exists) can be muddy, and after purchasing this product I tried it out on some muddy river water. After pre-filtering the water was still opaque from suspended sediment. In hindsight I'm not surprised: this pre-filter has a 40 micron screen, which means that clay (less than 2 microns across) and much silt (2-63 microns across) will go right through. If you take this on a hike, expect it to remove only obvious stuff, not fine sediments. BTW, I also tested a paper coffee filter and my bandanna as pre-filters, using the same batch of river water. The paper coffee filter removed slightly more sediment than this product -- to be expected, since the pores in such filters are about 20 microns across. The bandanna removed the most sediment -- not sure why. Both the paper coffee filter and the bandanna slowed down as more sediment was trapped, and the SteriPEN pre-filter was much faster to use. If you want to fill a water bottle quickly, as the first step toward purification, perhaps this product makes sense. For me, a dedicated pre-filter isn't worth taking along if it can't deal effectively with suspended sediment. I carry a bandanna on my hikes anyway, so that's what I'll use if I want to pre-filter water. But mostly I'll live with some trail water having a serious chocolate tinge.
Date published: 2015-09-14
Rated 3 out of 5 by from Not necessary I have brought it on a few long trips. I used it twice. I find this device to be bulky and unnecessary. Bring a few coffee filters or use a shirt if things are that bad. Otherwise, enjoy a small piece of fiber in your water. Relax... you're outdoors.
Date published: 2008-06-29
Rated 3 out of 5 by from Leaks We use these on our annual kayaking trips and although they do a good job filtering your water it leaks back out of the filter when you go to take a swig out of it so water pours down your chin or top. A bit annoying.
Date published: 2016-08-15
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How long does the filter last?  Do I need to buy replacements or do I just clean by rinsing in the opposite direction?

Asked by: Robotuner
SteriPEN does not really put a finite time frame on the Bottle Prefilter. With regular cleanings it should last a long time. Replacement filter cartridges can also be purchased separately at the link below:
Answered by: REIservice
Date published: 2015-09-20

Does the steriPEN water bottle prefilter fit a 16 ounce Nalgene bottle or a 32 ounce bottle?

Asked by: Neon65
This prefilter fits the wide mouth 32 oz. Nalgene bottles.
Answered by: REIservice
Date published: 2015-09-20
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