Water Treatment

No water source along The Colorado Trail should be considered safe to drink from directly, except for water available at campgrounds, picnic areas and the like that is clearly marked as potable. Don’t be fooled by the clear rushing water of a mountain stream or the seeming pureness of a pond high above treeline – animals, both wild and domestic (cattle and sheep are most common), can introduce protozoa and bacterial organisms to water sources even in the most remote areas. 

man treating water by an alpine lake

As a consequence, to avoid ingesting pathogens such as giardia lamblia or cryptosporidium that could ruin your backcountry trip – not to mention endanger your health – you should treat all drinking water by one of four recommended methods: boiling, filtration, chemical disinfectant, or by using an ultraviolet water purifier.

Here is a closer look at each:

  • Boiling is the simplest, if you have adequate fuel, and kills all known pathogens. While there is debate about boil times, a minimum of 5 minutes at a rolling boil is recommended.
  • Iodine disinfectant (or less-effective chlorine) is not as reliable as boiling, but provides some protection against giardia and most bacteria, but not crypto. Very cold water should be left to treat overnight.
  • Filters are popular for backcountry water purification, but check the specifications for individual devices before buying one. A filter with pores larger than 0.2 microns will let bacteria through. A system with an iodine matrix will kill viruses.
  • Ultraviolet water purifiers are relatively new on the scene. These battery-powered devices use UV light rays instead of chemicals to purify water for drinking.

treating water from a stream
In all cases, choose your water sources carefully, away from obvious animal hosts such as beaver and cattle, and take water from as close to the source as possible, such as a spring.

An additional reminder: Always practice Leave No Trace principles to safeguard the water supply for other users, including camping at least 100 feet from any stream, lake or spring.

Short video, “Filtering water on The Colorado Trail with a Sawyer Squeeze” by 2021 thru-hiker.