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There certainly are a lot of chemicals and devices on the market to provide us with “bug free” drinking water in the outdoors. At a glance, it would seem like these companies are all trying to scare us into buying their product just so we can get a clean drink out in the woods, or after a disaster.

If there are any scare tactics at work in the marketing of these products, don’t let them stop you from getting and using this equipment. These are not baseless fears. There really are some bad things in the water. Here’s a look at four of the most dangerous biological water contaminants in America’s creeks and waterways.


Depending on the location, the parasite Giardia lambia is probably the most common water contaminant to North America’s waterways. This nasty, single-cell freeloader migrates to the small intestine after you consume tainted water. Once there, it causes a medical condition known as giardiasis, and commonly referred to as “beaver fever.” The symptoms of this ailment include mild to severe diarrhea, which often lasts long enough to cause weight loss. In the modern world, these parasites can usually be cured quickly by getting a course of antibiotic like Metronidazole, which is an antibiotic, amebicide, and antiprotozoal drug. Without this drug, these symptoms could kill someone cut off from modern medical care.


Cryptosporidium is another parasite that is common in North American fresh water. This bug was little known for centuries, as the first case of cryptosporidiosis was not diagnosed until 1976. This biological water contaminant is still poorly understood, and it proves very difficult to treat. Some research indicates that cryptosporidium actually lives in the walls of your cells, a place where few medicines tend to linger. With symptoms similar to giardia, these parasites are often confused for one another. But with it being nearly impossible to exterminate, cryptosporidium is the one to worry about. Think of this thing as giardia’s more aggressive cousin, and likely a permanent resident in your body, should you drink even a few of these bugs. This creature typically gives us the most important reason to treat our emergency drinking water.

**Fluke Worms **

Flukes are a group of flat, parasitic worms that inhabit rivers, streams or lakes that contain livestock and wildlife feces. A set of particularly destructive flatworms are called Trematoda. These typically infect a person’s digestive system, but can also migrate to the brain, liver, lungs, and other vital organs. About 20,000 species of flukes are recognized worldwide. In humans, some of these species cause lung infestations that resemble tuberculosis and include fever, chronic cough and chest pain. Other species of fluke will go after a person’s liver, creating bile duct obstruction and liver cirrhosis. While that may not kill you, liver flukes can lead to chronic jaundice and a higher occurrence of liver cancer. If these parasites weren’t unsettling enough, most adult flukes are large enough to be visible to the naked eye. Most range between a 1/16th of an inch to one inch fully grown, but some species have topped out at seven yards long.

Bacteria (Primarily Salmonella and Vibrio cholerae)

Salmonella and Vibrio cholerae are two more forms of life that have the potential to make an outdoor water source deadly. Vibrio cholerae causes cholera, which manifests itself with diarrhea, nausea, vomiting and dehydration. This dehydration can be severe enough to cause a rapid electrolyte imbalance, leading to shock, which could be fatal.

Salmonella is the most frequent source of serious foodborne illness, but it can also be found in the world’s surface water. Salmonella, too, causes diarrhea and vomiting. Fortunately, these two bugs are not as widespread in the United States as they are in other parts of the world. The same can be said of viruses, which are more common in the fresh water of the tropics, Asia and Africa, than in the US.

Now that we are all sufficiently scared to drink the water, it’s a good time to remember that there are a host of pills, liquids and gizmos on the market that kill or filter all of this stuff. And don’t worry: If you get caught without any gear, boiling the water for 8 to 10 minutes will kill all these wiggle-tails too.

Tell us in the comments if you have had any of these bugs, and what damage they did to you. Hope you’re feeling better!