How To Filter Water / Why You Need to Filter Water

Don't be deceived by how crystal clear this water looks. It was refreshing to dunk my feet in this during a 22-mile hike, but there's bird poop, dead bugs, and who knows what else. (And, no I didn't make that happy face, I found it perfectly sitting there, looking back at me. The eyes are dead bugs, by the way.) 

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BACKGROUND
I was once about to embark on a solo backpacking trip in the Bob Marshall Wilderness - affectionately known as "The Bob" by locals - when I came across two older gentlemen moseying around their horse camp at the Benchmark trailhead. The older guy's name was, ironically, Bob. We got to talking and he introduced me to his horses, showed me how to pack for a horse pack trip, and asked me about my decision to venture out solo. You have to imagine this old classic Montanan rancher interacting with random Korean-American girl wandering by herself into a wilderness unfamiliar to most people outside of Montana. It's not where the visitors go; it's where the locals go. I like to believe my presence probably baffled him. Regardless, Bob was incredibly embracing, kind, and supportive.

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The next morning, I was packing up camp and Bob came by to check in. He looked at my water bladder and asked me why I was carrying so much water. (It was probably 2.5L.) I explained why and he proceeded to tell me how he just gets a cup and puts it right up to a spring and drinks straight from it. He's been doing that for over 20 years and he's never had a problem. I was tempted to leave my water bladder, take a cup instead, and chug water straight from a spring too! Who wouldn't want to believe a kind old man? I almost did, until I remembered...

"Oh right, that one time I got GIARDIA and ended up in urgent care hooked up to morphine! And that other time I spent three weeks recovering from an insane case of SALMONELLA and ended up in the E.R. Oh, and that month I spent in southeast Asia with the runs because of G.I. issues."

Yeah, really. I hope that thought scares you a little because water-borne diseases are no joke. I'm the queen of G.I. issues, so please hear me when I say it's horrible. When you're not sure if water is potable (safe to drink), you should always treat it. The absolute best way is to boil it for at least three minutes. But boiling water can be cumbersome and not always feasible. Below are the most common water-borne diseases and ways to treat it. 

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MOST COMMON DISEASES

BEST WAYS TO TREAT WATER

  1. Boiling water
    • This is the most reliable way of eliminating all potential diseases. 
    • Bring water to a rolling boil for at least a 3 minutes to make questionable water, potable. Boiling for 10 minutes will sterilize the water; this is unnecessary for drinking.
    • This is a cumbersome method. I don't know anyone who does this on a regular basis in the backcountry. But it is your safest bet!
  2. Filtration + Disinfection
    • This is the second best option to eliminate water-born diseases.
    • First use a filter to pass the water through a first round of purification. Then use a disinfection method for a second treatment measure.
    • I should probably start doing this since I'm known for contracting serious G.I. issues. 
  3. Filtration only
    • This can be a good option for purifying water, but depending on the device, it may or may not filter all viruses. In North America, it's unlikely that you need to filter out viruses, but nothing's ever for certain.
    • If I had to choose only one or the other as the safer bet, I would choose filtration only over disinfection only because filtering water will catch Crypto.
    • It's pretty fast, but it's heavier and bulkier than a disinfection method.
  4. Disinfection only
    • Iodine, Chlorine, or Chlorine Dioxide
    • Does a good job of killing bacteria, viruses, and (most of the time) giardia. But it's not proven to treat Crypto, which is more likely than viruses in the water.
    • It takes longer than filtration, but it's smaller and lighter.
    • Does most of the job, and tends to be fairly reliable.
    • Katadyn and Potable Aqua make lightweight tablets that treats for Crypto. The only major downfall is that it takes 4 hours to treat water versus the faster 30 minutes. (Listed below)

You can find more info from the CDC here & here.


Examples of filtration systems

Examples of disinfection treatment systems