Backcountry Water Treatment Options

While recent research has concluded that backcountry water sources (especially those at higher elevations) are cleaner than once thought, it is impossible to tell which water sources may be contaminated. Rather than risk serious intestinal discomfort there are many water treatment options available, but which is best? Choosing a water treatment system for backpacking can be a confusing and time consuming process. Below we review the options available and discuss the various pros and cons of each to help you decide.

Pump Filtration:

There are many different pump filtration systems out there. Most work by placing one end in the water you wish to filter and the other in a storage container and then manually pumping the water through the filter. Pump filters utilize a variety of filtration media including ceramic, fiberglass, silica, etc. Membrane filters use thin sheets of material with fine pores; they are relatively easy to clean but clog easily. Depth filters use thick layers of porous media; they can be harder to clean and if the media is cracked the filter is ineffective. Micron size (a measurement of the pore size in the filter media) varies by filter so make sure to select a filter with a micron size that is effective at straining most protozoa and bacteria.

Pros:

• effective against protozoa and bacteria
• strains out particulates
• relatively fast

Cons:

• not effective against viruses
• moving parts require maintenance
• can become clogged
• pumping too fast may reduce effectiveness of filters
• weight (varies by system)

Gravity Filters:

Gravity filters work by letting gravity push the water through the filter for you. Generally you fill a large bag with water and hang it from an obliging tree or rock. Some gravity filters come with storage (water filters into another compartment) while some do not.

Pros:

• lightweight
• easy to use
• few moving parts
• little maintenance required
• effective against protozoa, bacteria, & cryptosporidium
• relatively fast
• good for treating water for large groups
• strains out particulates

Cons:

• cost 
• does not work against viruses
• puncturing the bag or letting the filter freeze can ruin the system

Filtration Straws:


Straw type filtration systems work by filtering water as you sip. They are available with or without storage bottles.

Pros:

• lightweight
• inexpensive 
• easy to use
• effective against protozoa and bacteria
• little maintenance required
• strains out particulates

Cons:

• does not work against viruses
• for immediate consumption only
• must be replaced if it becomes clogged

UV purifiers: 

UV systems purify water by exposing microorganisms to UV light for around 90 seconds. The light inactivates microorganisms by disrupting their DNA.

Pros:

• lightweight
• effective against protozoa, bacteria, viruses & cryptosporidium
• does not change the taste of the water
• good for small bottles of water
• relatively fast

Cons:

• requires batteries
• bulb has a limited life
• effectiveness is lowered by cloudy water
• does not strain out particulates

Chemical Treatment: 

Iodine and Chlorine dioxide provide a lightweight option that is useful for treating large amounts of water. Typically tablets are dissolved in water; treatment usually takes between fifteen and thirty minutes depending on the chemicals used. When using chemical treatment it is important to follow the directions on the bottle.

Pros:

• lightweight & compact
• inexpensive 
• iodine is effective against protozoa, bacteria & viruses 
• chlorine dioxide is effective against protozoa, bacteria, viruses & moderately effective against cryptosporidium 
• useful for treating large amounts of water at one time
• great as a backup water treatment option

Cons:

• water may have a slight taste after treatment
• tablets/chemicals may become ineffective after their expiration dates
• cold water (less than ~60F (16C) decreases the effectiveness of the treatment and requires longer treatment time
• some people are allergic to iodine or shouldn't use it due to medical conditions
• does not strain out particulates 

Boiling:

Bringing your water temperature up to 212F (100C) is one of the simplest water treatment options.

Pros:

• very effective at killing all microorganisms

Cons:

• slow
• requires fuel & a fire
• not suitable for large amounts of water
• higher altitudes requires additional boiling time as water boils at a lower temperature 
• does not strain out particulates

More information:

A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use (CDC)

Backcountry Water Purification (National Park Service)

Backcountry Water Quality Q&A (REI)

Wildland Recreation: Ecology and Management

Hydration

Everyone knows that staying hydrated while participating in outdoor activities is important. We all think that thirst will trigger us to drink enough, but this isn’t always reliable. Depending upon level of activity, weather, altitude and our own fitness level, it’s possible to lose fluid so quickly that our thirst mechanism can’t keep up.

We lose fluid in two ways, sensibly (meaning we are aware of it) and insensibly (we aren’t). Normal sensible losses include elimination (peeing), and sweating. In dry climates, our sweat might evaporate so quickly that we aren’t aware of how much we are sweating. Insensibly, we lose fluid through breathing, and also through our skin (in addition to sweat glands). Normal respiration (when at rest) can lose about two liters of water a day by evaporation from the lungs, and skin “respires” too, losing about ½ liter per day.

On a normal day, we lose about four liters of fluid which we usually replace with consuming our drinks of choice and with meals. This amount can be dramatically increased by illness (vomiting or diarrhea).

The most common cause of increased fluid loss is through exertion. When we are active, we increase the amount of fluid we lose, and depending upon the humidity and the altitude, we can lose even more. The lower the humidity, and the higher the altitude, the more fluid is lost through respiration. During heavy exertion, we can lose between one to three liters of fluid per hour which can quickly put us in a deficit that is hard to make up if we aren’t drinking constantly.

The symptoms of mild dehydration include headache, dry lips and mouth, decreased urine output, fatigue, and even dizziness. Thirst may or may not be present. The effects of these symptoms are decreased coordination, and impairment of judgment. Dehydration can worsen symptoms of other conditions including diabetes, and increase the likelihood of other heat-related problems such as heat exhaustion and heat stroke.

When engaging in outdoor activity, especially in a very cold or hot environment, and more so at altitude, don’t wait until you are thirsty to drink. Try to drink a liter an hour, and to eat frequent snacks to replace needed electrolytes.

Learn more about dehydration: http://www.youtube.com/watch?v=q3bjUu_ONjc#t=214