Water Treatment for Hikers, Vol. 1 – Why we treat our water


One of the most important resources for a hiker is water. Without proper hydration, any hike you have planned is pretty much doomed. Without clean water, any efforts you make to maintain proper hydration are going to end poorly. Bacteria, viruses and parasites can be real problems and can have a real, sometimes life-threatening, impact on your hike.



What do you think was the biggest killer of soldiers during the US Civil War?

According to research done by historians for every 3 soldiers killed in battle, 5 died from disease. The diseases with the biggest death tolls were dysentery and typhoid.  According to records Dysentery was by far the biggest killer. Think about that. In a war where roughly 620,000 Americans soldiers died, approximately 65% died from disease, with dysentery being the biggest culprit. Dysentery is a type of gastroenteritis that results in diarrhea with blood. The diarrhea is so severe that your bowels are being evacuated faster than you can hydrate your body. This is a serious, life threatening situation and medical treatment is a necessity. 

                Dysentery can come from bacterial, viral or parasitic causes, so  let’s examine what lurks in our water that can affect our health. Amng the thing hikers will face, the 4 we will most likely encounter are bacteria, viruses, parasites and chemicals. Of those 4, here in the US we will be LEAST likely to encounter viruses and that will have an impact on how we treat our water as we will discuss later. The 5 most common things found in streams/ponds/lakes are Giardia, Cryptosporidium, E. Coli, Cholera, and Typhoid Fever (Salmonella Typhi).


Bacteria are single celled prokaryotic organisms. Prokaryotes are organisms without a cell nucleus, or any other membrane-bound organelles. What does this mean to you? Nothing. I am just being all sciencey. Bacteria can be beneficial or harmful. In the human body, bacteria are everywhere but since your immune system limits their growth in many systems, they are found in the largest numbers on your skin and in you GI tract. In a milliliter of fresh water, expect to find a million bacterial cells.  Common bacteria that concern hikers are E. Coli, Cholera (Vibrio cholerae), and Typhoid Fever (Salmonella Typhi).


A virus is an infectious agent that only replicates INSIDE the living cells of other organisms. Viruses found in water include but are not limited to Hepatitis, SARS, Polio, and Hand, Foot, and Mouth disease caused by Coxsackievirus or Enterovirus. Much less common in water sources in the United States (actually VERY rare), we aren’t going to really cover them.  Quick story. This past summer (summer of 2017) I was volunteering as a camp nurse for my church’s kids camp. We actually had a couple cases of Hand, foot, and mouth disease among the campers. These were the first cases of the disease I have ever seen in the US, but I suspect they came TO camp with the disease since they presented with symptoms in the first 2 days of camp. We immediately isolated them and sent them home for treatment.


Protozoa and Cysts are single-celled organisms, usually found in food and water that is contaminated by animal waste. Common protozoa encountered by hikers are Giardia Lamblia (giardiasis) and Cryptosporidium parvum (cryptosporidiosis).


Chemicals in water are extremely varied. The most common sources of chemicals in water is industrial or agricultural runoff. So many different varieties of chemicals are pumped into our water that I am not even going to get into them. Let me just say that you should exercise caution when drinking water from a source near any factory or farm, even more so from water that isn’t flowing. High concentrations of chemicals can NOT be reliably removed by either portable filters or purifiers, so again, be VERY cautious.


Below I list the 6 most common contaminants hikers might encounter. We are going to cover general signs, symptoms, and how to treat.


  • Giardiasis – Giardiasis is a parasitic infection caused by a protozoa, Giardia Lamblia. Giardia is one of the most common waterborne pathogens around the world and is transmitted via the fecal-oral route from ingested cysts. Also called Beaver Fever, it is caused by contaminated fecal matter entering a water supply. Unless you are one of the lucky who are asymptomatic, you will experience-
    • Diarrhea
    • Abdominal pain
    • Weight loss secondary to the infection blocking nutrient absorption in the small intestine
    • Less common are vomiting, blood in the stool and fever

Since Giardiasis usually resolves on its own, treatment involves treating the symptoms via hydration. Prevention is a matter of hygiene, to include hand washing and proper water treatment. All traditional water treatment methods are effective vs Giardia


  • Cryptosporidiosis – Cryptosporidiosis is caused by a cyst, Cryptosporidium parvum, that can cause respiratory and gastrointestinal illness. Cryptosporidium is also a very common pathogen. Like Giardia, transmission is generally via a fecal-oral route, but unlike Giardia it can also be transmitted via a respiratory route.
    • Watery diarrhea with or without a persistent cough

Treatment of Cryptosporidiosis is similar to Giardiasis, meaning you treat the symptoms via re-hydration and electrolyte therapy. Prevention is also similar, combining hygiene and proper filtration, but Cryptosporidium is highly resistant to chlorine disinfection, so if going that route make sure you use the proper concentration and that you treat the water for the correct length of time.


  • E. Coli infection – Most strains of Escherichia Coli are non-pathogenic to humans. As a matter of fact, I GUARANTEE you have E. Coli in your GI tract right now. While there are also virulent strains of E. Coli that can cause sever life threatening illnesses, as hikers we focus on strains that cause gastroenteritis. Symptoms include-
    • Nausea, vomiting, and diarrhea.

Treatment once again includes treating of symptoms and in since it is a bacteria, properly prescribed and administered antibiotics will effectively shorten the course of the illness. Since transmission occurs through the fecal-oral route, prevention comes down to proper hygiene, cooking of food, and effective water treatment. All the traditional forms of water treatment are effective.


  • Typhoid Fever – is NOT Typhus. Typhoid fever is cause by Salmonella Typhi, a bacteria. It is generally a 3rd world disease, transmitted via the fecal-oral route in contaminated food and water. Due to poor hygiene, it is a SERIOUS problem in India. INITIAL SYMPTOMS include
    • Fever (primarily a fever that rises in the afternoon), bradycardia (slow pulse), malaise, headache and cough.

Symptoms that occur as time goes by are progressively worse and involve more body systems with serious complications. Typhoid Fever is usually spread via a fecal-oral route, but can be spread by flying insects feeding on feces. Proper hygiene is necessary to prevent Typhoid Fever and all traditional water filtration forms are effective. Prevention is possible via vaccination and treatment includes treating of symptoms and antibiotics.


  • Cholera – cause by some strains of Vibrio cholerae, Cholera is a bacterial infection of the small intestine. Symptoms can range from none to mild, to sever, and can include-
    • Watery diarrhea that lasts a few days
    • Vomiting
    • Cramps

Transmitted via a fecal-oral route through contaminated food and water, with under-cooked seafood being a common source. Prevention includes vaccination, hygiene and water treatment, with all common water treatment forms being effective. Treatment includes treating of symptoms to include re-hydration and electrolytes therapy and antibiotics.


  • Norovirus – I am including Norovirus because of recent outbreaks on the AT. This is the outlier in the group. The general rule of thumb is that viruses aren’t an issue for hikers in the US. Every spring lately, at about the NC/TN line on the AT people are coming down with the virus. The symptoms include…you guessed it, GI issues. So now you have a bunch of people puking and crapping all over the trail, further contaminating the environment and spreading the virus to each other from the Smokies all the way up to Maine. Prevention includes good hygiene and water treatment, BUT since a virus is WAY smaller than the bacteria and cysts that filters are designed for, thus a water filter won’t do squat for a virus unless it is also a purifier or has a chemical purification component. Treatment involves treating the symptoms and giving your body time to heal itself.


In the next installment, I will discuss Water Treatment options.