Recreation - Wilderness 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.
PROTECT YOURSELF
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
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 that 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
For a PDF of this information, please click here.
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