In this video presentation, we dive into a critical topic to raise awareness about the increasing problem of cyanobacteria, or blue-green algae, in backcountry water sources. Cyanobacteria (also known as blue-green algae) cause toxic algae blooms (a.k.a. hazardous algae blooms, HAB) because of the presence of cyanotoxins. Cyanotoxins are harmful to humans and mammals (especially dogs) and can cause various symptoms, including skin rashes, eye/ear/nose/throat damage, liver damage, and neurological damage. As these harmful organisms become more common, outdoor enthusiasts need to understand their risks, how to identify contaminated water, and the most effective treatment methods to ensure safe hydration in the wilderness. This presentation provides valuable insights and practical advice to help you stay informed and safe on your adventures.
This module is part of our comprehensive online course, Water Treatment and Backpacking Hygiene. Explore the full course to deepen your understanding of water safety, effective treatment methods, and best practices for maintaining hygiene in the wild.
Learn state of the art best practices for water treatment safety and backcountry hygiene in this comprehensive online course. In Water Treatment and Backpacking Hygiene, you’ll learn the science behind various water treatment methods, how and when to use them, water treatment best practices, and information about health and hygiene on the trail and in camp. Targeted primarily to multi-day backpackers, expedition runners, long-distance hikers, institutional education students, working field professionals, and thru-hikers to ensure your safety and success in the wilderness. In this course, we also offer expert guidance on selecting appropriate water treatment systems, hygiene supplies, and more.
Gear Resources
In this video module, we discussed the use of two-stage filtration (hollow fiber membrane, followed by activated carbon) as a promising method for removing cyanobacteria and cyanotoxins from backcountry water sources. Currently, we recommend Hydroblu two-stage filtration systems for this purpose:
Inline hollow-fiber water filter with 0.1 micron pore size and 99.9999% bacteria removal, dual 28 mm threaded ends for bottle, inline, gravity, or straw use, rated up to 100,000 gallons and weighing about 2 oz (57 g).
The Activated Carbon module is made up of mixture of activated carbon and ion-exchange microbeads. Activated carbon adsorbs chemicals and heavy metals, and improves the taste and color of the contaminated water. The ion-exchange microbeads are an organic polymer substrate. These beads are porous, providing a large surface area for removing pollution, poisonous, and heavy metal iron from the water. The ion-exchange replaces these negative ions with innocuous ions, such as sodium and potassium. Additionally, this combination will remove unhealthy organic compounds such as chlorine, pesticides, herbicides, petroleum products, and cyanotoxins.
Discover more in Backpacking Light’s Water Treatment and Backpacking Hygiene Gear and Supply Resource Guide.
Related Content
- Gear Guides: Water Treatment and Backpacking Hygiene: Recommended Gear and Supplies
- Tips & Tricks: Using Alum to Clarify Muddy Water on Trips
- Webinar: Aquamira
Discussion
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Companion forum thread to: Cyanobacteria and Cyanotoxins in Backcountry Water Sources
In this video presentation, we dive into a critical topic to raise awareness about the increasing problem of cyanobacteria, or blue-green algae, in backcountry water sources.
Seeing the water sources on the Arizona trail or the CDT – lots of places where your only option is a cow pond, a tank full of algae, etc. Suggestions?
Well done presentation. Toxic algae has become a problem at Isle Royale National Park as well. Some of the inland lakes on the island will suffer from toxic algae blooms and the NPS has to issue “do not drink” advisories for visitors.
For first aid, charcoal is easy to make in most places below tree line. Can that help? How much do we need to eat?
Prevention is better, of course. I’m just thinking about what to do when things go wrong?
Bill: while charcoal is easy to make, and wouldn’t hurt you, what you really want is *activated* charcoal which has been heated in high-temperature steam or nitrogen to drive organics off the surfaces of former cell walls. Then the tremendous surface area of those microscopic structures can adsorb (with a “d” – a surface process) organic molecules from the air or out of water.
If you wanted to use DIY charcoal, the fresher the better.
But you’d have to administer it pretty quickly – before most of the toxics had been absorbing in the GI tract.
So in a pinch, charcoal would be far better to treat the water before drinking than as first aid after you noticed symptoms.
Thanks for that explanation, David.
Avoidance has work so far, and that remains solidly Plan A.
I suppose that some water really needs to be distilled to make it safe. If fuel is abundant (firewood), then it isn’t all that hard to do. Maybe that’s a good reason to carry a pot, a lid, and a smaller cup. Not that I’ve ever needed to do that — I just feel better knowing that I can. :)
I wonder if stillsuits feel clammy? Probably. Sigh.
Just got back from a Wind River trip. Due to high temps and drought, algal growth was significant. There were posted warnings at the Big Sandy TH about several lakes being contaminated with cyanobacterial toxins, and I assume this list was incomplete.
Reading through this thread, I see that there are several educated guesses that are reasonable but wrong. I went to the scientific literature to see what it could add to the discussion. Here’s the gist:
(Cerasino and Sarmaso, 2012, Jablonska et al 2024)
Bottom line – Ryan’s advice in the video is good: filter the bacteria to remove intracellular toxins, then remove extracellular toxins with charcoal adsorption.
EPA summary is here
The wrong but reasonable guesses I was referring to were actually in this older thread. Sorry for the confusion.
What is really like to see is someone take several water sample from the cyanobateria water. 1 sample as control, a 2nd sample running it through just a filter and 3rd running it through a filter followed by activated charcoal.
Send all 3 to a lab and get test results.
If I’m dire for water I’d do the filter and charcoal but having suffered from Giardia, I’m highly skeptical it’s still safe to drink.
So, given that this stuff can be invisible to the naked eye, how do we do risk assessment? Almost none of the alpine lakes in Washington even have data. Is it time to drop my preferred Aquamira solution? I’ve never had an issue but Ryan’s presentation of Alzheimer’s risk to exposure is a little unnerving.
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