How to Use a SteriPEN Pre-Filter in the Wilderness

How to Use a SteriPEN Pre-Filter

When you’re hiking in the wilderness, it is always a smart idea to filter or treat water from streams and lakes. Even at high elevations, there is the threat of bacteria, protozoa, and viruses that can make you sick!

Related content:
Hiking 101: Water Treatment
Hiking Lady Gear Reviews: Steripen Classic, Steripen Adventurer Opti
Does the SteriPEN pre-filter keep the Nalgene threads bacteria free?
Video: How to Use a Steripen to Treat Water

I am a long-time user of the SteriPEN UV-light based treatment, due to its reliability, size, and weight. Plus, unlike pump based filters, it also kills viruses, in addition to bacteria and protozoa. A Hiking Lady reader asked about the SteriPEN pre-filter, and to demonstrate how it works I filmed this short video:


  1. Mike says:

    I can’t find any videos or instructions as to why the SteriPEN Pre-Filter has the reversible bayoneted filter. Why would anyone want or need to reverse it?

  2. Hiking Lady says:

    Great comments. If a stream is quite shallow, I usually have better luck filling up by tilting the bottle into the flow of the water. The pre-filter is easily cleaned, so I don’t worry about it getting too gunked up because I just rinse it off when I’m done. I’ve never had an issue of it getting clogged. If a stream is really shallow, I just fill up my Nalgene as much as I can and still do a full SteriPEN treatment on it. I usually take a collapsible water bottle like a Platypus with me…so I will take that clean water, put it into the Platypus, then fill up the Nalgene again (to the extent possible) with stream water. If you have a collapsible bucket you can also use that to help fill up the Nalgene with water you want to treat with the SteriPEN. Happy trails!

  3. scsurvive says:

    You should turn the bottle 180 so that the entrance is opposite the flow of the water. This will reduce the debris and sediment that enters the bottle/filter and help to maintain the filters life.
    Also with a stream that shallow, how do you fill the bottle up? Do you simple put in as much water as you can?

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