Water Purification

Under Construction

Water in third world countries and taken from streams or lakes my have microorganisms which can cause diarrhea (Dysentery) and or Flatulence (gas). It is caused by a sudden intestinal infection. It may be called gastroenteritis, Montezuma's Revenge, Turista, or the GI Trots. Water sterilization is an important skill for backpackers.

Backcountry Hiking: The Giardia parasites and E. coli bacteria are considered to be the main problems. Viruses are infrequent.
In the 60's and early 70' most Sierra Nevada hikers, including myself, drank water directly from lakes and streams with no problems. In the middle 70s stories of giardia dangers started making the rounds.
Studies in the 90's and early 2000's showed the incidence of giardia was still very low.

In "Giardia Lamblia and Giardiasis With Particular Attention to the Sierra Nevada" , published in the Yosemite Association News Letter #4, March 18, 2002, Robert L. Rockwell, PhD, says,

"Given the casual approach to personal hygiene that characterizes most backpacking treks, hand washing is likely to be a much more useful preventative strategy than water disinfection!"

The only time I ever got sick from the water was when the septic system at Gold Coast Lodge at Squaw Valley overflowed contaminating Squaw Creek and the water at the lodge below. That's when I switched from drinking scotch and water to beer and rusty nails.

Developing Countries: Bacteria and viruses such as Hepatitis and parasites are all common.

See more information below.

Water Treatments for Potable (drinking) water

Boiling:
According to the Wilderness Medical Society, "Water temperatures above 160° F (70° C) kill all pathogens within 30 minutes and above 185° F (85° C) within a few minutes. So in the time it takes for the water to reach the boiling point (212° F or 100° C) from 160° F (70° C), all pathogens will be killed, even at high altitude."
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Boiling Temperature
Sea Level 212° F      10,000    194°
5,000'    203         15,000    184
7,500'    198         20,000    175
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See: How Long Do You Need To Boil Water at Survival Topics
and OA Guide to Water Purification
Pros: No taste, no pump, no chemicals
Cons: Time consuming, requires fuel and stove.
Iodine:
Products: Potable Aqua Plus tablets ($7), Polar Pure ($10)
Pros: Cheap, lightweight, easy to use
Cons: Bad taste, crypto will still get you, thyroid problems
Chlorine dioxide and Silver ions:
Products: Potable Aqua and Micropur MP1 (Katadyn), McNett's Aquamira
Destroys viruses and bacteria in 15 min., Giardia in 30 min. and Cryptosporidium (parasite) in 4 hrs.
Sodium Chlorite (NaClO₂) reacts with Citric Acid to produce Chlorine Dioxide (ClO₂)
Pros: Kills everything, simple, inexpensive, little to no flavor
Kills bacteria and viruses in 15 min. and cysts (giardia and crypto) in 30 min. with clean warm (68°F) water. Cons: Undissolved tablets and drops are extremely toxic
Getting the powder on your hand and rubbing your eyes can result in a trip to the hospital. Takes 4 hrs. to kill Crypto in cold or dirty water.
Use gloves or wash powder off immediately. Whatever you don't touch your eyes after handling these tablets.

Silver ions are attracted to bacteria by polar absorption. After penetrating the cell membrane, the ions damage the bacteria's DNA, thus preventing further multiplication.
Since it is slow acting (hours to treat) but doesn't gas off like chlorine, it is better suited for preventing bacterial growth in previously treated water that will be stored for long periods of time than it is for backpacker use.
Katadyn Micropur Forte uses silver ions and chlorine.
Use:
Shake the water container. Then turn your water container upside down and loosen the cap to bleed water over the threads. If your container is clear keep it out of the sun.
Dirty water or water < 40° F should be treated for 4 hours for Crypto.
However Crypto is in such low concentration that most people say 30 min. is enough. See notes below
See Using Micropur at Philmont Boy Scouts and Backcountry.com
Filters and Purifiers:
Purifier pumps water thru a unit like a filter, but uses electrostatic attraction to remove viruses.
Products: Many filters, First Need Deluxe Purifier ($95)
Pros: No taste, removes sediment, tried-and-true technique
Removes Giardia, Cryptosporidium and all bacteria and microorganisms.
Cons: Bulky, lots of squatting, easily clogged with sediment, expensive filter replacements, simple filters don't remove viruses because they are too small.
See MSR vs Katadyn below.
Katadyn MyBottle with virus filter:
This is a 3-layer filter system, which adsorbs viruses and minute particles on the basis of electrokinetic in-depth filtration. This is possible due to the differences in the electric charges of the materials.
$60 at REI See MyBottle Factsheet
UV light:
Products: SteriPEN from Hydro-Photon ($149), AquaStar Deluxe from Meridian Design ($99)
Pros: Fast, no flavor, kills viruses
Cons: Expensive, bulb durability concerns, battery-powered
Turbid water reduces effectiveness, so I carry a few coffee filters to filter out suspended solids.
UV disrupts the reproductive process of DNA, however according to wikipedia, if the neutered microbes is exposed to visible light (specifically, wavelengths of light over 330-500 nm) for any significant period of time, a process known as photoreactivation can take place, whereby there becomes a possibility for repairing the damage in the bacteria's reproduction DNA.
How to Treat Water With Solar Power | eHow.com:
Put clear water into clear or light blue tinged soda bottles, glass jars or sturdy plastic bags and lay them on their sides where they will get midday sunlight for six hours.
Electrified Brine
Products: MIOX from MSR ($130)
Pros: Little to no flavor, can treat large volumes of water
Cons: Expensive, requires disposable "testing strips"

Source: Liquidate the Bugs in the May, 2006 AMC Outdoors magazine.

Dish Washing

Bleach:
Set out 3 buckets:
- Wash pot: contains hot water with a few drops of biodegradable soap.
  Some say to strain the dishwater, put the scraps in a bag to cary out and broadcast what remains, others say to bury it.
- Hot-rinse pot: clear, hot water.
  You may need tongs to avoid burning your fingers.
- Cold-rinse pot: cold water with 3 drops of bleach for 2 quarts (1/2 gal).
Note: ChlorineÕs effect increases with time, so dipping a plate in chlorine and then rinsing in plain water is less effective than dipping in chlorine and letting it dry.
Air Drying:
Air drying for 8 hours will also work.

See: How to Clean Camp Kitchen Gear Properly | Trails.com
How to Clean Dishes on a Camping Trip - wikiHow

Products

MSR vs Katadyn:

As of the summer of 2011 the Katadyn Hiker Pro was the most popular, although MSR Miniworks still had it's adherants.
Filters for the Katadyn Hiker Pro are $50 and for the MSR Miniworks are $40.

The Katadyn has a pleated glass-fiber element that has a little better flow and is easier to pump, but only filters 0.3 micron particles. It is also lighter 11 vs 16 oz.
The MSR had a ceramic cartridge which filters particles down to 0.2 microns, but the ceramic cartridge could break if dropped.
I didn't find any evidence of problems with either the 0.3 micron limit (e-coli are 0.3 micron and Cryptosporidium and Giardia are larger) the Katadyn or broken cartridges with the MSR.
Both will get hard to pump after heavy use. The handle on my Hike Pro broke when someone pushed it too hard after sharing with 15 people for 3 days.

The Platypus® GravityWorks™ Filter was also recommended by a PCT thru hiker. If filters particles to 0.2 microns. It comes with 2 - 4 liter bags (1 for dirty and one for clean water) which it fills in 2.5 min. (1.6 l/min) Filters are $13

The Katadyn Basecamp is a similar gravity feed filter.
I holds 2.5 gal. (9.5 liters) which it will filter in 15 min. (0.6 l/min). It uses the same filter as the Hiker Pro.

Water systems for surface water are health devices, not camping accessories. They must work in a variety of conditions. Beware of products that are well suited for certain conditions but advertised to work in all conditions. Most travelers need a product that performs well in a variety of water conditions.Your health is our concern Ð please choose your personal drinking water system carefully. Source: Katadyn

See:
Chart at MoonTrail.com
Katadyn Hiker Pro vs. MSR Miniworks water filters? at SurvivalistBoards.com
Katadyn Hiker vs MSR Sweetwater Guardian at TrailSpace.com

The Katadyn Hiker Pro;
After 3 days with 14 people using it from what appeared to be clear water from a lake it got hard to pump. The fine mesh filter protector screen was clean but the filter cartridge was brown.

How to get your water:
Water from a lake may be better than from a stream because the natural UV radiation from the sun will kill microbes. Collecting from the output of the lake is the best place.

Collect water just below the surface to avoid floating debris and sediment at the bottom.
It's easier to use a water bottle to scoop water and put it in a collapsible bucket and filter from there rather than filtering directly from the lake or stream.

I cary some coffee filters to filter dirty water before using any of the above purification methods. pouring thru a bandana works also.

More Information on the risk:
In "Giardia Lamblia and Giardiasis With Particular Attention to the Sierra Nevada" , published in the Yosemite Association News Letter #4, March 18, 2002, Robert L. Rockwell, PhD, says,

"Ask the average outdoors person about Giardia lamblia or giardiasis, and they have certainly heard about it. Almost always, however, they are considerably misinformed about both the organism's prevalence in wilderness water, and the seriousness of the disease if contracted.
With the advent of the Internet, the amount of information one can easily find on the subject is voluminous. Unfortunately, most of it is flawed in important aspects.
Our wilderness managers are in a position to educate the outdoor public about the real culprit in the Giardia lamblia story: inadequate human hygiene. When they acknowledge that Sierra Nevada water has fewer Giardia cysts than, for example, the municipal water supply of the city of San Francisco, maybe they will turn their attention to it.
"Given the casual approach to personal hygiene that characterizes most backpacking treks, hand washing is likely to be a much more useful preventative strategy than water disinfection!"

In "Giardiasis as a Threat to Backpackers in the United States" published in Wilderness and Environmental Medicine, 1999 Thomas R. Welch, MD., & Timothy P. Welch, say,

"Forty-eight of the 50 state health departments in the United States responded to a questionnaire about giardiasis in their jurisdictions. The agencies had reports of 34,348 cases during 1991 and studied 80 outbreaks in the same period. Nineteen of these outbreaks were attributed to consumption of contaminated drinking water; only two outbreaks were reported among individuals identified as campers or backpackers. Only two departments considered water-associated giardiasis to ba a problem for backpackers in their jurisdiction, and neither had any data to support this concern."

Chris Townsend has a good section on water safety in The Backpackers Handbook. He says,
"In 2002 he went on a five-week hike in the High Sierra, never treating any water and didn't get sick."

According to the May 2006 ACM Outdoors: "No study has ever been done on back-country water quality in the Northeast. While most experts agree that the vast majority of sources are probably safe, the consequences of acquiring an intestinal infection are not worth the risk."

An article "Microbiology" in the Dec. 2003 Backpacker states:
An American Water study of treatment plants in 14 US states and one Canadian province in 1991 found:

Giardia          17% of samples
Cryptosporidium  27%
Standards have been raised since then.

A 2003 American Water study of six watersheds found:

Giardia          23%
Cryptosporidium   4%

However levels of cryptosporidium were so low your chance of ingesting an infectious dose is approximately 1 in 5,000.
Studies showed that it took an average of 132 Cryto cysts to cause a problem.
You'd need to dring gallons to get that much.
However if your imune system is compromised because of Chemotherapy, AIDS or other reasons you should be more careful.

A UC Davis Medical School report, "Backcountry Water Quality Tests Are Good News For Campers" in December 2004, published in Wilderness and Environmental Medicine, Vol. 15, Issue 4 says:

"Except for some heavily used areas, streams and lakes in the high country of the Sierra Nevada are generally clean and fresh. UC Davis physician Robert Derlet and pathology researcher James Carlson present data gathered from nearly 100 locations throughout the Sierra Nevada during the summer of 2003, including Yosemite, Sequoia and Kings Canyon national parks. Their goal was to analyze wilderness water quality for the presence of harmful bacteria such as E. coli, which is typically an indicator of contamination from human or animal waste.
Running counter to popular belief, the two researchers downplay the risk of picking up Giardia in backcountry drinking water. In the Sierra Nevada, E. coli and other pathogenic bacteria may pose a greater risk than Giardia for causing waterborne illnesses in people.
Derlet has mostly found low levels of E. coli, primarily in regions below cattle grazing tracts and popular campgrounds
They quote a 1993 study "Cyst acquisition rate for Giardia lamblia in backcountry travelers to Desolation Wilderness, Lake Tahoe." by Zell SC and Sorenson SK. J Wilderness Med. 1993;4:147-154.
What's impressive is that more than half of our water sampling sites had no water quality problems whatsoever," said Derlet, a professor of emergency medicine at the UC Davis School of Medicine and an avid backpacker with 30 years of experience hiking in California's high Sierra. "People still should use water filters or purification techniques like boiling drinking water in the backcountry."
...
Lakes are typically 'cleaner' than creeks, possibly because the ultraviolet rays of sunlight work better at killing off bacteria in calm waters of a lake than in the tumbling flows of a stream; Bacteria readings appear higher at the beginning of spring runoff rather than later in the summer when water levels are lower and water quality is thought to be poorer;
Valley air pollution could be contributing to water quality problems in the Sierra Nevada.

The time between being infected and developing symptoms is 7 - 14 days. The acute phase lasts 2 - 4 weeks.

last updated 15 Aug 2012