Is the Water Safe to Drink?
We hope your visits to your National Forests will be enjoyable, and they will be if you avoid hazards that may be encountered in the great outdoors.
A Hidden Hazard
One hidden hazard you should know about is a disease that may be contracted from drinking untreated “natural” water. The disease is an intestinal disorder called GIARDIASIS (gee-ar-dye-a-sis). It can cause you severe discomfort.
The disease is caused by a microscopic organism, Giardia Lamblia. The cystic form of giardia may be found in mountain streams and lakes. These natural waters may be clear, cold and free running. They can look, smell, and taste good. You may see wildlife drinking without hesitation from these sources. All of these indicators sometimes lead people to mistakenly assume that natural waters are safe to drink. Giardia may or may not be present, but there is no way to tell by looking at the water.
Disease-Symptoms and Treatment
Although giardiasis can be incapacitating, it is not usually life threatening. After ingestion by humans, giardia normally attach themselves to the small intestine. Disease symptoms usually include diarrhea, increased gas, loss of appetite, abdominal cramps, and bloating. Weight loss may occur from nausea and loss of appetite. These discomforts may first appear a few days to a few week after ingestion of giardia, and may last up to 6 weeks.
Most people are unaware that they have been infected and have often returned home from vacations before the onset of symptoms, but if you have drunk untreated water you should suspect giardiasis and so inform your doctor.
With proper diagnosis the disease is curable with medication prescribed by a physician. If you think you might not remember the word “giardiasis”, save this brochure to show to your doctor.
There are several ways for you to treat raw water to make it safe to drink. The most certain treatment to destroy giardia is to boil water for at least 1 minute. Boiling also will destroy other organisms causing waterborne disease. At high altitudes (above 10,000 feet), you should maintain the boil for 3 to 5 minutes for an added margin of safety.
Chemical disinfectants such as iodine or chlorine tablets or drops are not yet considered as reliable as heat in killing giardia, although these products work well against most waterborne bacteria and viruses that cause disease. The amount of iodine or chlorine necessary to kill giardia depends on water temperature, PH, turbidity, and contact time between the chemical and the parasite.
Until current research determines the right amount of chemical and duration of contact time that will work against giardia under a variety of water conditions, chemicals cannot be recommended for routine disinfections of water for giardia. In an emergency where chemical disinfection is necessary, use an iodine-based product, since iodine is often more effective than chlorine. If possible, filter or strain the water first, and then allow the iodine to work at least 30 minutes before you drink the water. If the water is cold or cloudy, wait at least an hour, or use more iodine.
Alerts & Warnings
- Sierra NFSafety Advisory: Road and Recreation Facilities Closure Extended
- Bass Lake Ranger District plans to initiate winter/spring prescribed burning
- High Sierra Ranger District plans fall/winter/spring prescribed fire projects
- High Sierra Ranger District will be changing hours of operation
- Recreation Fee Program Accomplishment Highlights 2021
- Public Meeting Creek Fire Ecological Restoration Project Video
- Seasonal Visitors Center Closure