Safe Drinking Water

 

North Kaibab Trail approaching Cottonwood Campground along Bright Angel Creek.

 

While traveling in the backcountry, river running, or hiking, you may need to use water from the Colorado River, side streams, pools, springs, or other natural water sources. There may have been a time when it was safe to use such sources without treatment, but that is no longer the case. Any untreated water has the potential to cause illness if it is not properly disinfected.

In addition to bacteria, viruses, and parasites, some waterways within Grand Canyon National Park contain naturally occurring cyanobacteria. While not all cyanobacteria produce toxins, some can release harmful cyanotoxins under certain conditions. Visitors should understand these risks and follow safe water collection and treatment practices.

 

Filtering water from the Colorado River. Wash your hands before collecting water. It does no good to treat your drinking water if you recontaminate it during collection.

Disinfection Procedures

Wash your hands before collecting water. It does no good to treat your drinking water if you recontaminate it during collection.

Silt particles inhibit effective disinfection. If the water is muddy or cloudy, allow sediment to settle undisturbed for several hours. Alternatively, add a small amount of a clearing agent such as alum (aluminum sulfate). The suggested dosage is 1/5 teaspoon per gallon. Mix vigorously and allow the water to sit for five minutes, stirring twice. Once the silt has settled, carefully pour the clear water into another container or draw water from the top.

Filter the clear water through a minimum absolute 1-micron filter or one labeled as meeting ANSI/NSF International Standard 53 for "Cyst Removal."

Filtration alone is not sufficient to guarantee safe drinking water. After filtering, disinfect the water by adding two drops of household bleach or five drops of tincture of iodine per gallon of water. Allow the water to sit for at least 30 minutes before drinking. Very cold water should sit longer. You may also follow the manufacturer's instructions for commercially prepared water treatment products.

OR

Bring the Cleared Water to a Roiling Boil for One Full Minute

• At elevations above 6500 feet (2000 meters), such as on the canyon rims, increase the boiling time to three minutes.

• Treated water must be stored in clean and sanitized containers.

• More information from the CDC on safe drinking water is available here >

 

Cyanobacteria sample identified in the inner canyon

NPS Photo

Cyanobacteria in Grand Canyon

Cyanobacteria are naturally occurring microorganisms found in freshwater around the world. Some cyanobacteria can produce toxins that may be harmful to people and animals if consumed.

At Grand Canyon, some types of cyanobacteria grow on rocks and sediment along the bottoms of streams and waterways, forming mats that may appear dark green, brown, black, or blue-green. While cyanobacteria have been identified in Grand Canyon waterways such as Bright Angel Creek and in the Phantom Ranch area, park hydrologists are continuing to study when and where toxins are produced and what environmental factors influence their occurrence.

Water Collection and Cyanobacteria

The greatest potential risk for backcountry visitors is collecting or filtering water directly from areas where cyanobacterial mats are present. When these mats are disturbed, toxins may be released into the surrounding water.

It is important to understand that standard backpacking water filters are designed to remove bacteria, protozoa, and sediment, but they do not remove dissolved cyanotoxins to safe drinking levels. Similarly, boiling water or chemical disinfection methods such as bleach or iodine will not remove cyanotoxins that are already dissolved in the water.

Reduce Your Risk

When collecting water in the backcountry:

• Avoid collecting water directly from or immediately adjacent to visible cyanobacterial mats.
• Do not disturb cyanobacterial mats while collecting water.
• If possible, collect water from areas where visible cyanobacterial growth is absent.
• Follow all posted advisories and guidance regarding water sources.
• Check current park alerts and advisories before your trip.

 

Consequences

Everyone has preferences and beliefs that may affect personal decisions. If you are participating in a commercial river trip or guided backcountry hike, guides are required to follow established drinking water treatment procedures. If you are hiking or boating on a private trip, the National Park Service strongly encourages you to follow these same practices.

While some waterborne illnesses may be mild, individual responses to disease-causing organisms vary. Likewise, the health effects of cyanotoxins depend on the type and amount of toxin present and the level of exposure. Following safe water collection practices helps reduce your risk of illness.

Contacts

If you have questions regarding drinking water, or if you have become ill while traveling in the Grand Canyon backcountry, please contact: Park Sanitarian [phone] or Backcountry Information Center [phone].

Check the Backcountry Updates and Closures webpage for current information on trail conditions and situations affecting the backcountry (including drinking water availability in the Corridor).

 

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The information on this page is also available as a PDF file and can be viewed with Adobe Acrobat. PDF files retain the look and feel of the original document (including typography, page layout, and graphics).

PDF file - Safe Drinking Water

 

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Additional backcountry info can be found on the following webpages.

Backcountry Permit Regulations Hiking Tips Hiking FAQs Trail Courtesy

Day Hiking Guided Hikes Summer Hiking Winter Hiking Weather Dangers

Trails / Use Areas Distances Private Stock Food Storage Safe Water Updates / Closures

 

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