Backcountry Water Treatment 101

Backcountry Water Treatment 101

Why does this concern me?
The further away from developed cities and regions one gets the higher
the probability that there are contaminants in water sources.
There are 3 primary types of Pathogens we are trying to avoid:
Protozoa – Cryptosporidium and Giardia. Hard outer cyst
protects against some chemicals. Relatively large (1-20 microns)
and easy to filter out.
Bacteria – E. Coli, Salmonella, Campylobacter, Shigella.
Midsized pathogens between .1 and 10 microns.
Viruses – Hepatitis A, Rotavirus, and norovirus. These are
too small to be filtered out, between .005 and .1 microns. A
concern for underdeveloped countries and overcrowded areas
(human waste). These need to be removed or neutralized. Not
usually a concern in US and Canada.
 1 micron = 1 millionth of a meter. < This period is 50 microns
 As few as 10 microorganisms can cause symptoms.


Filtration – physically straining out protozoan cysts and

bacteria through a filter element. This is accomplished by “size
exclusion” but only effective down to .4 microns (viruses are too small).

Purification – this method is effective against all 3 types
pathogens and can be done by chemical or UV treatment.

Factors to Consider
Filter vs. Purifier – know what you are trying to avoid and
basic methods of avoiding it.

Types of Filters and Purifiers – effort required varies, as
does the wait time before water is ready.

Know best practices – follow basic hygiene and usage guidelines.

Tips and Best Practices
- Separate and clearly designate dirty and clean containers
- Pay close attention to directions (cross contamination)
- Seek out the cleanest water possible (murky sources)
- Keep your hands clean
- Gather water from the surface
- Keep camp, toilet, dishwashing station areas at least
200ft. from water source.

All devices used to treat water (other than chemical) will have an
internal element or cartridge. Filter components utilize microscopic
pores that catch debris, protozoa, and bacteria. Many filters and
purifiers will use an “activated carbon” element that is effective at
removing unpleasant taste (leaf tannins) and reduces contaminants like
pesticides and industrial chemicals.
Pre-Filter – a pre-filter removes large particles before they reach
the main filter/purifying element. Although natural particles pose no
health risk they can affect the ease of the process, frequency of
maintenance, and the lifespan of the element. A pre-filter is a great
accessory when dealing with murky water (leaf debris, mud, silt,
Improves treatment process and flow rate as well as improving
effectiveness of chemical treatment
Essential prior to UV treatment of unclean water

Types of Filters
-Pump Filters:

Pros: precise output, access to shallow sources, element is replaceable.

Cons: pumping sucks, field cleaning required, heavier and bulkier than other options.

-Gravity Filters:

Pros: gravity does all the work, large output, element is replaceable.

Cons: hanging can be tricky, slower process, shallow source can be a challenge, field cleaning required.

Bottle Filters/Purifiers:
Pros: easy & quick, element is replaceable, lighter & cheaper
Cons: quantity is limited to bottle size, field cleaning required

Squeeze Filters:
Pros: easy & quick, element is replaceable, can double as a gravity or straw style, lighter, smaller, and cheaper.
Cons: quantity is limited to vessel size, field cleaning required.

Straw Style:
Pros: quick & easy, lighter, cheaper
Cons: must be at water source, 1 person option, cleaning, and not all elements are replaceable.

Types of Purifiers
UV Purifier: disrupts DNA so the pathogen cannot reproduce,
therefore not cause illness. Pre-filter is highly recommended.

Pros: easy & quick process, no element cleaning
Cons: batteries, water quality impairs treatment, pre-
filtration required, and multiple treatments for large groups.

Chemical Purification– this treatment method is effective
against all pathogens and usually iodine or chlorine based. Can be drops,
pills, or gadgets that mix base chemicals.

Pros: easy use, very inexpensive, small and very light, great backup method.
Cons: wait time (up to 4 hours), taste (iodine), Iodine is not
effective against Cryptosporidium and a concern for pregnant women
and those with thyroid issues.

Boiling – combats everything. Bring to rolling boil for 1 minute, 3
minutes if above 6,500 ft.
Pros: water quality not a factor, readily available backup
Cons: time and effort, wait time (cooling), need extra fuel.

Common Filters and Purifiers

Filters: MSR MIniWorks
MSR Trail Shot
Sawyer Sqweeze
Sawyer Mini
Katadyn Hiker
Katadyn Vario
Katadyn Hiker Pro
Katadyn BeFree
Platapus Gravity Filter