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How to Purify Water When You Are Camping or Backpacking

"Outbound" Dan Human has been drinking out of streams, ponds, and puddles for several years on various backpacking and paddling trips.

Scooping water from a stream with a Nalgene.

Scooping water from a stream with a Nalgene.

Water is the only drink for a wise man

— Thoreau

That Stream Looks Clean...

Remember that backpacking trip a couple of weeks ago when you drank directly out of that pristine mountain stream that cascaded through a thousand glistening stones? Now forget that sublime moment and think about where you are now—sitting on the toilet for the past three days. You should have purified your water!

The tricky thing about water is that it doesn't matter how "clean" it looks, you can't see those nasty little microorganisms (unless you pack a microscope).

In this article, we'll review the advantages and disadvantages of the most popular water purification and treatment methods for backpacking and camping. For those of you without an inclination for the wilderness, the ability to purify water is a critical emergency skill that everyone should master. You never know when disaster will strike.

An electron micrograph of giardia.

An electron micrograph of giardia.

In an age when man has forgotten his origins and is blind even to his most essential needs for survival, water along with other resources has become the victim of his indifference.

— Rachel Carson

So, What's in the Water?

Though Mark Twain said, "Water, taken in moderation, cannot hurt anybody." sometimes even one drop of water can make you sick. So what kind of pathogens can you find while backpacking in the wild?

  • Bacteria:

Bacteria are single celled organisms which infect humans through contaminated water sources. E. coli and Salmonella are some of the most common waterborne bacteria.

  • Giardia:

Also known as "Beaver Fever," Giardia is a protozoan and holds the distinction of being the number one parasite in the United States. It's called "Beaver Fever" because the parasite is passed through the feces of mammals. After the 7-10 day incubation period, Giardia causes diarrhea, fatigue, and loss of appetite.

  • Cryptosporidium:

As hearty as they come, "Crypto" is another protozoan you can find in your drinking water. According to the CDC, Crypto is so resilient because it is "protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very tolerant to chlorine disinfection." Though Crypto infections generally resolve themselves after a week or so, the intestinal distress and fevers aren't the most pleasant of times.

  • Viruses:

Generally in North America, waterborne viruses are not an issue for backcountry travel. However in certain areas of the world, especially where sewage treatment is an issue, viruses are a major concern. In a disaster like Hurricane Katrina, where water is contaminated by a myriad of human sources, assume viruses to be present.

  • Chemical:

Mankind's influence on the watershed is greatest in the amount of chemical contamination in nature's water sources. Chemical contamination includes manufacturing and agricultural chemicals. Hint: Never draw water downstream of a farm or factory!

Backpackers hiking in areas with rampant hydrofracking like the Allegheny National Forest must be mindful of the dangerous chemicals used during fracking.

Removing all toxins from water is impossible with most kinds of backcountry purification devices.

Backpacking in Winter?

Winter backpackers deal with a whole other dimension of water treatment and procurement. Check out "Water for Winter Wandering: A Backpacker's Guide to Safe Drinking Water in the Colder Months."

Boiling is an effective means of water purification.

Boiling is an effective means of water purification.

The Old Standard Boiling Water

When municipal water sources fail, townships are placed on "boil water" notices. This method, which only needs a heating source to bring water to a boil, is a must-know for anyone and a great backup method for backpackers.

According to Mountaineering First Aid, "disinfection occurs during the time that water heats from 160 oF to boiling." Therefore bringing water to a rolling boil should neutralize most pathogens, as most would perish well before that.

Advantages of boiling:

  • No special equipment is required besides a pot and a heat source.
  • Effective at treating viruses, bacteria, and protozoans.
  • Great for winter campers melting ice.

Disadvantages of boiling:

  • Very fuel intensive.
  • Process is slow and not easily done midday on the trail.
  • Must wait for water to cool before drinking.
Chemical water purification: Polar Pure, Potable Aqua, Aqua Mira.

Chemical water purification: Polar Pure, Potable Aqua, Aqua Mira.

No taste chemical purification

Expert Tip

Don't add Gatorade or any kind of flavoring to your water until the chemicals have completely disinfected the water.

Chemical Water Treatment

A favorite amongst lightweight backpackers, chemical purification neutralizes many of the pathogens found in water. Before using chemicals, consult your doctor to make sure the methods are compatible with any medical conditions you may have.

Chemical purification is the number one choice of people building their own disaster emergency kits. The low cost and small size are attractive to people preparing for the worst.

Polar Pure (Iodine crystals):

This is one of the most cost effective ways of purifying water. Each bottle costs about $11.00 and treats upward of 2,000 quarts of water. At 3 oz it is a little heavier than potable aqua, but for longer trips, it is fantastic. Many long-distance backpackers on the Appalachian and Pacific Crest Trails favor Polar Pure.

  • Effective against Giardia
  • Effective against viruses
  • Indefinite shelf life with no expiration date.

Aquamira (Chlorine dioxide):

This product is a favorite amongst backpackers, due to a lack of taste; many people (including the company) claim that aquamira actually improves the taste of water. Aquamira works in colder water temperatures, so it is a favorite amongst winter backpackers.

Just add 7 drops from part A and 7 drops from Part B to the cap, let it mull for about 7 minutes. Then add the solution to the water and wait about 30 minutes.

  • Great taste.
  • Lack of EPA testing, limits claims on what aquamira actually treats.
  • EPA testing shows that it kills bacteria for certain.
  • Many users claim it is effective against giardia and cryptosporidum

Potable Aqua (iodine tablets):

This is the lightweight champ among chemical purification. You can purchase it as a one stage treatment or in a two stage pack. The two stage packs contain a taste neutralizer that is added after the iodine kills the nasty critters in the water. Just add 2 tablets to a quart of water and let it sit for about 30 minutes.

  • Taste is described by many as "yucky" without neutralizer.
  • 4 year shelf life until opened.
  • Kills most waterborne pathogens


Backpackers on a budget have used bleach in a small eyedropper for a long time. Just add 4 drops of unscented bleach and wait about 30 minutes.

  • Really bleachy taste
  • Inexpensive
  • Effective against giardia and bacteria


If you don't clean your threads after using chemical water purification, then place your lips on the bottle you just dipped, you are asking for trouble. After waiting the 30 minutes for the chemical to work, loosen the bottle cap about 1/4 turn then shake the bottle so water seeps out onto the threads.

Katadyn Guide water filter.

Katadyn Guide water filter.

Katadyn Hiker Pro

Expert Tip

Even though filters remove particulates in water, they clog your filter much faster. Always pump from the clearest water you can find.

Water Filters

Love gadgets and chunkless water? You should check out the assortment of water filters on the market.

Most pumps filter out contaminants down to about .2 microns which is small enough to eliminate most waterborne nasties like bacteria and protozoans.

Though filters are easy to use, novice and veteran hikers alike misuse them by contaminating the output hose with the inlet hose. Always treat the inlet hose and anything that touched untreated water as hazardous and keep it in a separate bag while transporting.

There are two main types of filters:

  • Membrane or Pleated filters
  • Easy to use and clean, no backflushing.
  • Clog more quickly.
  • Less expensive.
  • Usually more durable.
  • Example: Katadyn Hiker:

    • Capacity 200 gallons
    • Output: 1 quart per minute.
    • Weight 11 oz.
    • Filters bacteria, protozoa, cysts, algae
    • Retail: $79.99
    • Replacement Cartridge Retail: $39.99
  • Depth filters (usually ceramic)
  • Backflushing can clean the filter.
  • More expensive.
  • Ceramic filters are less durable.
  • Greater filtering strength.
  • Example: MSR Miniworks EX Microfilter
    • Capacity: Up to 400 gallons
    • Output: 1 quart per minute
    • Weight: 14.6 oz.
    • Filters bacteria, protozoa, cysts, algae
    • Retail: $89.99
    • Replacement Cartridge Retail: $39.99
Pumping water with the Katadyn Hiker.

Pumping water with the Katadyn Hiker.

Filters like the Frontier Sport and quick and easy to use.

Filters like the Frontier Sport and quick and easy to use.

Scoop and Go Bottle Filters

This is the most simple and easiest filter to use. Just scoop and go! These water filters are ideal for fastpackers and Search and Rescue team members who don't have time for traditional purification methods.

With the exception of the hinge on the cap, there are no moving parts. The filter, which filters out most Giardia and Crypto, nestles tightly in the top of the bottle. Just fill up the bottle, screw on the top, tip over, suck and squeeze.

  • The cartridge from the Aquamira Frontier Sport lasts about 100 gallons
  • The bottle fits easily in most bike water bottle cages.
  • This system is not ideal for group water purification.
  • It can be difficult to "gulp" water with this kind of filter.
The Steripen Adventurer UV light pen.

The Steripen Adventurer UV light pen.

Steripen UV water purifiers

UV Light SteriPEN

Looking for a lightweight and quick way to make your water safe to drink with no taste? Try a UV light lamp. These battery-powered wonders use ultraviolet light to disrupt the DNA of bacteria, parasites, and viruses. The light renders water pathogens harmless in just a couple of minutes.

SteriPEN is the major manufacturer of UV lamps for purifying water while backpacking. This company produces multiple UV lights from solar rechargeable models to even a hand crank version.

Frequently Asked Questions About Using UV Light Pens

This sounds complicated, steripens must be hard to use?

Not at all, actually. To use the Adventurer model, just fill up a quart of water, push the button on the pen and wait till it blinks. While blinking, submerge the pen in the water and stir for about a minute until the light turns off.

Sounds easy, how can you screw this up?

You'd be surprised. Most people after dipping their nalgene in a pool of water and sterilizing it with a UV pen, fail to wipe off the water droplets. Once you touch your lips to the threads, whammo, you just made yourself sick.

Wipe off any water droplets, use a water dipper, or use a steripen pre-filter to avoid that problem.

How long do the batteries last?

The batteries on the SteriPEN Adventurer will last about 100 water treatments; the lamp itself will last about 8,000 water purification treatments.

Purifying water with a SteriPen.

Purifying water with a SteriPen.

What is the Best Water Purification Method?

So, which method for purifying water is the best for your next backpacking trip? As you can see, there are advantages and disadvantages to each method and nothing is absolutely perfect.

Personally, when I'm hiking by myself I either use Aqua Mira or a SteriPEN UV light. However, when I'm out canoeing or backpacking with a group, I always filter the water first with a Katadyn Hiker. Sometimes, if the water source is extra questionable, I'll treat the filtered water with my SteriPEN.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2012 Dan Human


princess on November 22, 2012:

water is life. we need to take care of it.

water is life ..

we are water..

if water is healthy..

we will be healthy.......................................

Dan Human (author) from Niagara Falls, NY on October 21, 2012:

As long as you keep the filter clean and dry, your Katadyn Pro should last for years to come. You never know when you'll need it. Just throw an extra plastic bag in the case, in the event you have to keep the hoses separate.

I have used improvised pre-filters around the acorn water-intake before. It does keep some of the silt out of the device; however, it does slow the intake down a little bit. A handkerchief would work well though - just secure it with a heavy rubber band.

Thanks for the comment John-Rose!

John-Rose from USA on October 21, 2012:

I got one of the Katadyn hiker Pro filters years ago for emergencies, but never used it. I actually just pulled it out the other night to do my annual inspection and everything looks like new. I never thought about keeping the two hoses separate.

If I had to filter out super dirty water with it do you think a handkerchief wrapped around the end would help keep any muck from clogging the filter?

Dan Human (author) from Niagara Falls, NY on April 18, 2012:

I'm sure you'll like your MSR filter, it is certainly nice to have unchunky water. Just remember to backflush your filter every so often.

Thanks for commenting Adventure Colorad!

Adventure Colorad from Denver,CO on April 18, 2012:

Very well written Dan! I've used boiling to purify my water for years. I recently piked up an MSR purifier, but I haven't had a chance to use it very much. Nothing ruins a trip to the mountains like bad water!

Dan Human (author) from Niagara Falls, NY on April 06, 2012:

Though I've never contracted the big G myself, I've seen others afflicted with it. I guess that is why I tend to be a little careful when it comes to purifying water. Thanks AurelioLeo

AurelioLeo on April 06, 2012:

Giardia is the worse. I have seen first hand what happens when you drink water that wasn't properly purified. thanks Outbound Dan great hub.

Dan Human (author) from Niagara Falls, NY on April 05, 2012:

I found a couple muskrat den holes up the creek from where I filmed this, so there was probably Giardia in the water. I won't mention the pollution or soil run-off upstream either.

I learned the hard way about cleaning your threads when I was in the Army, well me and 90% of the task force...

Thanks for stopping by and leaving a comment jenubouka!

jenubouka on April 05, 2012:

Awesome, great information for those who may assume that river water is "clean." It is not, and some have found this out the hard way. I never even though to clean the threads of a water bottle as well, this is an incredible tip to remember when using these methods. Great article.

Dan Human (author) from Niagara Falls, NY on April 03, 2012:

Glad you liked it valleyforge84, thanks for stopping by!

valleyforge84 on April 03, 2012:

Fantastic! I Love It! I'm always looking for new ways to survive!! voted up!