If you hike or backpack in areas that have large amounts of decaying vegetation, like the forests of North America, you’re going to come across natural water sources that have a sickly red, orange, or yellow color. The tea-like coloring is caused by tannins that have leached out of the trees, grasses, and leafy plants, and into the local water supply. This coloring is harmless and the water can be filtered or purified by regular means for human consumption. While it’s aesthetically displeasing and may impart a slight bitterness to the water, tannins do not pose a health or medical issue.
Some water filters can partially remove tannins from the water, particularly those with an activated carbon component like the Katadyn Hiker Pro, which can make the water more palatable. The MSR MiniWorks Ceramic Filter can also remove tannins, but must be brushed (cleaned) occasionally to restore its normal flow rate. However, tannins will reduce the lifetime of most hollow fiber filters such as the Sawyer Squeeze, the HydroBlu VersaFlow, and the Katadyn BeFree unless they are backflushed more frequently.
More Frequently Asked Questions
- Ultraviolet Water Purification 101
- Cold Weather Water Treatment and Purification
- How Much Water Do You Need for Day hiking?
- How to Prevent your Water Filter from Freezing in Cold Weather
- Hiking and Backpacking Hydration Systems: Pros and Cons
I’ve been wondering about this for years. Thanks for the answer. It seemed to be more common in New York and New Jersey on the AT, but I’ve occasionally run into it in New England. Adding an electrolyte mix would help mask the flavor.
I was hiking the SHT in Minnesota a couple years ago. After a heavy rain all of the rivers looked like flowing root beer. The water looked funny, but was completely fine to drink. Good article to provide some clarity on this topic.
I just think if it as “free wilderness red wine” :)
One issue with treating tannic water might be with chlorine disinfectants (apparently less so with ClO2 based ones). As the water is quite full of dissolved organics (hence the colour) and chlorine reacts with these organics to form trihalomethanes and many other long-term harmful disinfection by-products, I’d not do that regularly – the water might come out clearer, but it would be full of DBPs, which are a long-term risk.
All of the fresh water I came across in Tasmania was brown with tannins and clean enough to drink without filtering.
Great article, thank you!
Make sure you know the coloration is from tannins. In most of In any region that is heavily mined, you will run into water affected by acid mine drainage.
EXCELLENT POINT! THANKS!
Thank you for this Philip ! We have a lot of this in the water in PA.
Back in the colonial days, they figured out that water from Lake Drummond (VA) could be taken on ocean voyages without getting foul. Lake Drummond is tannic, due to it being a shallow depression in a huge bed of peat. Possibly caused by a long-burning underground peat fire thousands of years ago.
Great post, thank-you.
I have the Kat. Hiker Pro and a Kat Be-Free. I even have the old Katadyn ceramic that I bought in the eighties.
Tannins can be a bit toxic after about a month on the trail. You *might* get a case of the “scoots” from it, but, generally do not hesitate to drink it.
Be aware that iodine is deactivated by tannins, so iodine-based disinfectors like Potable Aqua may not work
Have never heard this before. Source? Not suggesting I don’t believe you but did a quick google search and couldn’t find anything related to this either.