Backcountry Water Sources

Beaver Pond - White Mountains

When you’re out on a long day hike or a backpacking trip, you will eventually run out of water and need to resupply. When that happens, it helps to understand what’s a good water source and what’s an iffy one.

Water Sources to Avoid

Here are some general rules of thumb that I use across the board, regardless of the water filter or purification system I’m using.

  1. Don’t drink from puddles or other standing sources where there is no inflow and outflow.
  2. Avoid taking water from beaver ponds. Beavers are associated with the spread of giardia.
  3. Don’t refill your water reservoir under a water fall or cascade because it will have more suspended solids in it that can interfere with water purification.
  4. Avoid taking water from a large river that is downstream from a town, industrial or mining activity.
  5. Avoid taking water that’s running down a treadway or water bar because it is also likely to have a lot of sediment in it.
  6. Avoid standing water sources, particularly cattle or horse troughs, that animals drink from.
  7. Avoid drinking a lot of orange or red colored water that has dissolved tannins in it. You’re likely to encounter this in heavily forested areas, in late autumn.
  8. Avoid drinking water from a stream that runs though cultivated fields or animal pastures.

That said, I’ve taken water from each one of these backcountry sources and lived to tell the tale. Still, I try to avoid them.

Stream in the White Mountains

Good Water Sources

While you can’t see what the quality of a water source is, you can hear it, and the sound of trickling water is what I look for when I refill my water reservoir. It doesn’t matter if it’s a larger stream like the one above, or a very small one, trickling it’s way down a slope through a maze of roots and rocks. As long as there’s an steady stream, and none of the other red flags listed above are present, I’m likely to trust it. After that, I’ll purify it before consumption.

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  1. I know you kind of, sort of, said it, but allow me to clarify:



  2. Thanks for the emphasis. Personally, I prefer purification over filtration. Legally this requires extra certification by the EPA Technically, it means you're getting rid of all viruses, bacteria, and protozoans. I'm not saying that filters are inadequate – they're just not adequate for me.

  3. Ok, you do not NEED to purify or treat all water and half the time what comes out of a spout is sketchier than what I find in the backcountry. With that said, if you don't feel comfortable with a source, you should treat it. I'm consistently finding clean sources on my trips, but I'm confident in my identification skills.

  4. Hey Phil…could you expand on the tannis…I was in WV and literally every water source was clear but colored…all were good running sources. I filtered and me still had a yellow hew. I double up with aquamira

  5. That's absolutely true Chris. These are just my preferences. What would you say are your rules of thumb for identifying water sources that you don't feel you need to filter or purify? I assume this is a teachable skill.

  6. Alex has a good post about tannins in water, see… and read the comments. The extra aquamira is unnecessary.

  7. It's definitely teachable but also comes with some practice. Around here, I will only skip treatment if the following conditions are met: 1) I'm taking water right where it comes out of the ground, 2) I'm not near a road and the chance of cows, horses, etc. being on the land above where I am is slim to none, 3) there is plenty of good, green moss growing around the source. If I find something that meets those and there isn't some obvious sign to treat, I drink it straight and enjoy the crisp, fresh taste. I pretty much always treat from rivers and creeks or anywhere else people and domestic animals are likely to have crossed, accessed, etc.

    Obviously you run in to a lot more sources where treatment isn't necessary out West than you do here on the East Coast.

  8. Good stuff Chris. I have been known to drink directly from springs myself.

  9. Giardia is a microscopic parasite that lives in the intestine and is passed in feces. Because the parasite is protected by an outer shell, it can survive outside the body and in the environment for long periods of time, i.e. months.

    That means that if an infected cow, raccoon, horse, hiker or whatever came in contact with that water source some 3-6 months ago, that water could be infected.

    The reality is you can NEVER tell if a source is "clean" unless you have a microscope and know how to properly identify Girardia.

    You can play russian roulette with your health and drink water without treating it. Maybe you'll get it, and maybe you won't. It will have more to do with luck and less with your ability to determine "clean" water with the naked human eye and other factors like moss, color, or flow rate.

    Treating water costs pennies and takes just minutes. Not treating water, and getting sick costs thousands of dollars in missed work, missed fun, and health care costs.

    But hey, if drinking directly from a mountain stream is worth diarrhea, stomach or abdominal cramps, and vomiting for 2 – 6 weeks, then knock yourself out!

    Personally, I've seen too many people succumb to Girardia to ever want to go there myself. They all thought they could "tell" if the water was clean or dirty and they were all wrong.

  10. This post doesn't seem to be based on any scientific evidence of the incidence of pathogens at various water sources. This post seems to be more of "I'll take my water from here if it the feng shui is good."

  11. It not something that's easy to make general and scientific claims about across different water sources, places, and countries. I thought I made it pretty clear that this is what I do. You can call that feng shui if you want. I'm not offended. In fact I rather like that.

  12. Sorry if I was so abrasive, but I would love to see pathogen counts from various water sources to see how useful common sense/folk knowledge really is.

    It's like you could become an ultralight backpacker without ever using a scale to weigh your gear, but it sure does help to use one.

  13. No worries. It was a valid point and I'd love to see the quantitative data too. I love busting myths with science, myself.

  14. Long ago I read that giardia spores tend to sink, so you're better off getting water from a still source, like a lake, rather than a running stream.

    I'm not completely sure of the veracity of this info- anyone else heard this?

  15. I don't like to risk it so I always filter my water. One time in the mid 90s we were hiking on the Appalachian Trail and the only source of water was a barely trickling creek down stream from a beaver pond. The water was somewhat clear but shallow. I have to tell you the Sweetwater Guardian did a great job of filtering the water. It got rid of all the sediment and the water tasted good. And we never got sick. I figure if my filter can handle that it can handle anything. I have never felt the need to purify water with chemicals if I'm using the filter. If I was outside of the US I might but not in it.

  16. "I was in WV and literally every water source was clear but colored"

    If WV = West Virginia, then the coloration you observed is likely the result of iron oxide compounds caused by acidic coal mine drainage. Probably not a health issue since exposure is likely transitory, and iron compounds are not especially toxic.

  17. Some years ago in Grand Teton National Park, the rangers were pushing treating all the water and then one told me he didn't when he was alone. My brother rarely treated the water he got hiking in Montana until… the experience! He treats it now.

    I always have treated my water. I'm very conservative and don't like to gamble. The last two trips to South Rim in Big Bend, Boot Springs wasn't running and I had to get my water from stagnant pools in the creek, surrounded by bear droppings. I filtered the big lumps through a paper towel into my water bottles, dropped in the iodine tablets, waited thirty minutes, then boiled it, then dropped Crystal Light in it to make it palatable. My grandson and I didn't get sick and we actually enjoyed it. Of course, I've found that after a few miles with a pack on my back, any water tastes good.

    I got a filter I learned about on this blog and will use it next time. I'll likely also switch to chlorine dioxide over iodine, although I've never found the iodine taste to be objectionable. It's just that chlorine dioxide kills more stuff if you give it the time.

  18. Great post, I agree with every bit of it. My heuristic is "how much opportunity has something/someone had to crap in this water". Fast running, post rainstorm rivers at 7000 feet? Not much. Meandering water meadow streams just down from a designated campsite? Rather a lot.

    You asked about data. There's a good section in Long Distance Hiking by Roland Mueser:

    Long-Distance Hiking: Lessons from the Appalachian Trail<img src="; width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

    And besides, real men simply strain water through their sock and add a dash of whisky…

  19. Chris – I own that book and took a look at the chapter on water purification. I'd forgotten how well-written it is. Mueser concludes that there isn't much quantitative data to justify water purification based in part on the cost of doing a comprehensive study (100 gallons per source based on a Stats of Maine study).

    What is interesting is the incidence of Giardia carriers in the human population 3-4%.

    He concludes that communal eating (shared gorp bag) and dirty dishes and hangs may be the greatest cause of GI distress – also see Ryan Jordan's recent article on the benefits of hand and cookware washing at

  20. Being a geology major, I can tell you that springs are safe. That water has flowed through hundreds of feet of porous rock. With that said, it can depend if it is in a valley and something toxic spilled. Unfortunately, chemicals and most filters won't filter out pesticides and heavy metals. On my AT thru, I drank directly from mountaintop springs. If I couldn't see the source, it got treated. My treatment? I filtered the water through a t-shirt for suspended solids, then used 2 drops per quart of household bleach, shake, and wait 20 minutes. I used this the whole way and never got sick.

  21. I purify my water with Betadine. I got used to the taste easily, never had a problem.

  22. James Richardson

    Treatment and filters are fine much, probably most of the time. I use AquaMira when on the go. But for certainty, other than dissolved chemicals or elements, at other times, boil it. Technically, it doesn’t have to reach a full boil, but with a full boil you have clear proof.

  23. “Being a geology major, I can tell you that springs are safe.” Sorry, not true. Although someone can usually get by without treating spring water, spring water has also made many people sick. Pathogens have often been found in spring water.

    “Hibler (1988) found Giardia cysts in 19% of springs”

    “In several studies, the consumption of untreated water from a lake, river, or spring and rainwater was significantly associated with cryptosporidiosis.”

    I have gathered most of the relevant scientific studies on backcountry water quality and treatment here:

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