Water Purification Systems for Camping or Backpacking

That mountain lake, river or stream water may look crystal clear and refreshing, but can sometimes contain microscopic waterborne pathogens that don’t play well with humans – none of which are visible to the human eye. Every year campers and backpackers become ill by drinking bad water. According to the Journal of Wilderness Medicine, the incidence of wilderness-acquired diarrhea (WAD) occurs in the range of 3–5% annually. Talk about ruining an otherwise great camping trip. It’s just not worth the risk. Especially with today’s simple and effective water purification systems for camping or backpacking.

How do I know if I need to Purify my Water?

Waterborne pathogens are much too small to be seen by the human eye. So there is really no way for us to visibly determine if the water we’re about to enjoy is safe to drink. But, there can often be clues to help us determine whether or not the water is likely to contain harmful microorganisms.

  • Ask local rangers for known water quality issues in or around the area you intend to camp or trek through.
  • Look for signs of recent rain. This causes rivers and streams to rise and stir up bottom sediment which contains heavier protozoan critters not meant for human consumption.
  • Look for trails shared by both pack animals and humans, especially when trails run along the banks of rivers and streams. Animal defecation is a leading cause of water contamination in wilderness areas.
  • Look for areas where cattle graze or defecate close to a water source. This is even more a concern if it’s near popular or established campsites. According to Robert Derlet, professor at the University of California-Davis School of Medicine who has been testing the water quality in lakes, creeks and streams in California’s Sierra Nevada for nearly 20 years, Giardia infected cattle excrete nearly 100 million Giardia cysts per day, and pack animals excrete about 12 million per day.
  • Look for evidence of sloppy human behavior or a prolonged human visit. Unfortunately, not all campers and backpackers are aware of the risk to the environment when bathing or washing dirty dishes directly in a river or lake. This is really bad practice and is illegal in U.S. National Parks. Substances found in soaps or detergents can provide nutrients that help sustain and expand populations of pathogens.
  • Look for signs of algae or foam in the water source.  Both are signs of high risk water and should be avoided.
  • Beware of any water in or around areas of recent natural disasters such as hurricanes, tornadoes, earthquakes or floods, as physical breaches can allow external contaminants into enclosed water systems.

Waterborne Pathogens that hurt Humans

There are three types of Waterborne pathogens: Protozoan, Bacterial, and Viral. All three can survive in fresh water supplies used by humans around the world. And all three can reek havoc if ingested by normal healthy humans. According to the World Health Organization (WHO), contaminated water accounts for 80% of all diseases contracted during travel. Symptoms can range from nausea, diarrhea, vomiting, or worse. Sadly, for people with compromised immune systems, such as those with AIDS or individuals undergoing immunosuppressive therapy, infection may lead to dehydration and in rare cases, death.


Giardia Lamblia

Giardia Lamblia Protozoa

Protozoan cysts (Cryptosporidium parvum and Giardia lamblia) are the primary protozoan critters attributed to wilderness-acquired diarrhea and are the most common protozoan pathogens found in backcountry water in the United States. Giardia is THE most common cause of non-bacterial diarrhea in North America. But, because they are relatively large in size – 1.0 micron to 300 microns (1 micron = one millionth of a meter) – they can be effectively removed by filtering your water before drinking.


Campylobacter Bacteria

Bacteria occur naturally in water and can thrive in backcountry water. Most aquatic bacteria are not harmful to humans and actually serve an important role in the ecological chain. However, certain infectious bacteria including E. coli, Salmonella, and Campylobacter have been found in wilderness water sources, suggesting animal and human fecal contamination. Smaller than Protozoa – 0.1 micron to 10 microns – these pathogens can be primarily eliminated by filtering, but additional water purification using chemical or Ultraviolet light may be needed to guarantee success.

Hepatitis A Virus

Hepatitis A Virus

Viral pathogens are rare in U.S. backcountry waters. They generally do not do well in the open, exposed, harsh environment of most U.S. wilderness areas. Most experts argue, if camping and backpacking is limited to just the United States, the risk from viral infection is nearly non-existent.  This may not be true for third world countries where poor sanitation and favorable climates exist for viral growth. If camping outside of the United States, strongly consider purifying all water for viral contamination. Viruses are even smaller than bacteria – 0.005 micron to 0.1 micron. Because of their super small size, they cannot be eliminated from water by filtering. Instead, the water must be purified using chemical (halogen) or Ultraviolet methods.

Types of Water Purification Systems for Camping

There are four primary types of water purification methods available for campers, hikers and backpackers: boiling, filtration, ultra violet, and chemical. Let’s take a closer look at each type of purification system.

Boiling – If there is one sure-fire way to guarantee safe drinking water, this is it. At sea level, boiling water for at least 1 minute will kill most harmful pathogens. You will need to add one additional minute for each 1,000 feet of elevation you are at when boiling water. This is because the boiling point of water decreases with elevation. So for example, if camping at 8,000 ft, boil your water for at least 9 minutes. You also need to let the water cool enough to be drinkable. So this method, though reliable, is really slow.

Water filtration – Water filtering alone is generally sufficient to remove protozoan and bacterial pathogens. Water filters alone will NOT remove viruses though, so beware if traveling outside of the U.S. or Canada! Water filters work by passing source water through a ceramic or glass fiber micro-filter which blocks harmful protozoa and bacteria. Many systems incorporate a carbon component as well to aid filtering and improve taste. Nearly all filter systems allow maintenance in the field. There are three types of water filters available for outdoor enthusiasts.

  • Gravity – These moderately priced systems work by filling one bag with source water which is then hung on a tree or pole. Using gravity, the water passes through a tube with an inline filter to a catcher bag of equal volume. Available from small 2-liter sizes to nearly 3-gallon basecamp models, most systems can filter 1 liter of water in about 1 minute – fast, reliable, and lightweight.
  • Pump – These handy devices come in a variety of prices from less than $50.00 to $300.00. They all work by using a built-in hand pump to draw source water into a tube, usually directly from a lake or stream, through the internal filter back out to a small bottle or container. These are super handy when out on the trail and want water without a long wait – though you do have to work for it. Water output rates vary by model, but are generally in the range of 1 to 2.5 liters per minute requiring 40 – 70 manual hand pumps.
  • Squeeze bottle – This least expensive option is great where smaller volumes of water are needed. Operation couldn’t be easier. Simply fill the bottle directly from a lake, stream or river, screw on the top (with built-in filter) and enjoy clean filtered water instantly. Replace filter cartridges as needed. Perfect for day hikes, kayaking or traveling.

Ultra violet systems – For more than 100 years, ultraviolet (UV) light technology has been recognized as an effective method of water treatment on all microbial nasties. It is part of the water purification process used by many municipal water systems in the U.S. and most developed countries. Ultraviolet light prevents microbes from reproducing by modifying their DNA linkages. Although the pathogens remain alive, they are effectively sterile. Unable to multiply once ingested, they can no longer make you become ill.

It was in 1999 that Hydro-Photon, Inc. received its first SteriPEN® patent setting the stage for portable UV water treatment. This company nearly owns the entire market for portable UV water purification systems. They have a diverse and well conceived product line for outdoor enthusiast and travelers alike. And, SteriPEN products have been tested by the Water Quality Association (WQA) certifying that SteriPEN products purify water safely and effectively.

SteriPEN offers five models designed for outdoor use. All are small and lightweight making them easy to pack and carry when you’re hiking or camping. Using small camera style batteries for power, water purification takes just 45 seconds for 1/2 liter of water. They even offer a solar charging case that recharges lithium batteries while providing a handy storage unit. One model use no batteries at all, but instead has a built-in hand crank to power the UV lamp. Operation is super simple with an on board timer. Just set it for 0.5 or 1.0 liter water volume, slowly stir the wand in the source water until the timer tells you to stop and voila – drink up!

Chemical treatments – Chemical purification of water has been in use since the 1940’s. Iodine or Chlorine are the two types of halogen chemicals (a class of non-metallic elements) used for treating water. Both Iodine and Chlorine are effective at killing most waterborne pathogens. However, Iodine is NOT effective against Cryptosporidium cysts. The two biggest drawbacks with using halogens are they require from 30 minutes to 4 hours to work and they add a chemical taste to the water. The chemical taste can be reduced, if not completely eliminated, by the addition of vitamin C or powdered drink mix containing vitamin C. The addition of vitamin C converts chlorine and iodine to chloride and iodide – both tasteless chemicals.

Warning: People suffering from thyroid disease, immune system impairment, or iodine allergy should not use iodine. Pregnant women should not use iodine for longer than one week.

Kits containing chemical water treatment tablets are sold at outdoor recreation and camping supply stores everywhere. Potable Aqua, the most common brand sold, offers both Iodine and Chlorine based products at very reasonable prices. Unopened bottles of Potable Aqua tablets remain effective up to four years if properly stored and around six months once the bottle is opened.

The chart below details the Advantages and Disadvantages of the four primary methods of water treatment commonly used by campers, hikers, and backpackers.

Water Treatment MethodAdvantagesDisadvantages
Boiling• Kills nearly all microorganisms
• Inexpensive
• Does not affect taste of water
• Time consuming, especially at high altitudes
• Must wait for water to cool to drink
• Uses up fuel
• Requires boiling container and bottles
Filtering• Removes protozoan and bacterial pathogens from water
• Can remove bad chemicals and pesticides
• Fast
• Can improve taste of water if using carbon component
• Does NOT remove viruses
• Requires maintenance
• Some units can be a little pricey
• Pump units require manual pumping
Ultraviolet (UV) light• UV light does not alter the taste of water
• destroys over 99.9 percent of bacteria, viruses and protozoan cysts
• Small, lightweight, fast
• Requires power source
• Run the risk of running out of power unless using hand crank model
Chemicals(Halogens)• Small
• Very portable
• Inexpensive
• Limited shelf life
• Iodine does NOT kill cryptosporidium
• Chemicals affect taste of water
• Requires 30 min to 4 hr to work
• Some people cannot take iodine

As mentioned earlier, if you are drinking wilderness water only in the U.S. or Canada, using a water filter alone should be sufficient to make it potable. To be extra safe, or if you must drink questionable water, using a two-stage method is better. Use either chemical tablets (if you have the time) or a water filter followed by UV light treatment. Use the carbon water filter first to physically remove as much of the pathogens and chemicals as possible, then follow it with a UV light treatment to purify what’s left. Not only does the water taste better, but it is absolutely safe to drink from any source.

If you enjoyed this article, you might also want to check out my Complete Guide to Choosing a Tent or my article on Choosing a Sleeping Bag for kids and Adults.