Canadian Canoe Routes - Technique - Problems

Technique | Problems | Giardia

Hypothermia
Wind and Waves
Thunderstorms
Damage to Canoes
The Accidental Swim
Biting Insects
Pinned Canoes
Getting Lost
Sweepers
Giardia
Poison Ivy
Self-Recovery

Giardia is a microscopic parasite that may or may not be present in any water you drink from natural sources.

Giardia Cyst

Giardia parasites are protected by an outer layer called a 'cyst.' This shell allows giardia to exist outside of the body for relatively long periods of time, and also makes the parasite resistant to chemical water treatment (such as chlorine). Research has shown that cysts can live up to three months in water.

Ingestion of giardia cysts may result in a disease called giardiasis, commonly known as 'beaver fever.' The disease may not manifest itself for 2 - 10 days, but when it does, it's not a pleasant experience. Symptoms include nausea, weight loss, fever and diarrhea.

For the most part, symptoms last a few days, and within a month or two the body can usually rid itself of the parasite using its own natural immune systems. For individuals with weakened immune systems, the disease can last much longer and medical treatment may be required.

Purifying Water

The oldest, simplest and cheapest method for purification is by boiling your drinking water. By the time water reaches a boil, nearly all pathogens will be killed, but the generally accepted guideline is a rolling boil for five minutes.

Chemical treatments such as chlorine or iodine can also be used to purify water, but caution must be taken with the process. For a start, water should be at a temperature of 25°C (75°F), which is a much higher temperature than is found in most lake and river water in Canada. To be safe, water should sit until it reaches that temperature (possibly overnight). Chlorine is an 'iffy' choice - iodine is a much better option, although it has the disadvantage of making the water taste unpleasant. The addition of ascorbic acid (vitamin C) will neutralize this taste.

Prolonged use of iodine can cause thyroid problems, so it should only be used occasionally or as a short-term solution. Pregnant women or people with thyroid problems should not use iodine treatments.

It should be recognized that boiling is a far better option than either chlorine or iodine for water treatment. If boiling is not practical or possible, the following guidelines should be used for chemical disinfection:

Chlorine

Regular bleach (for laundry use) usually has about 4% to 6% available chlorine. Check the chlorine content before using, and add according to the following guidelines:

1% chlorine (10-20 drops / litre)
4% to 6% chlorine (2-4 drops / litre)
7% to 10% chlorine (1-2 drops / litre)

Water should stand after treatment for 30 - 60 minutes. If water is murky or very cold, the treatment time should be lengthened to several hours over even overnight.

Iodine

Regular tincture of iodine (first aid) can be used. A 2% iodine solution should be added to water at a rate of 5-10 drops per litre. If iodine tablets are used, follow the directions on the bottle. Remember that iodine tablets are not stable, and the effectiveness will begin to deteriorate after the bottle has been unsealed.

As with chlorine, the water should stand after treatment for 30-60 minutes, or longer if water is turbid or cold.

Water Filters

Water Filters will efficiently remove giardia and suspended solids from water. They will not remove viruses unless they are also classed as purifiers, which generally use an iodine-impregnated resin to kill the viruses.

Detailed information on water filters can be found on the water filter page in the equipment section of this site.

Water Treatment - What Works, What Doesn't

	Boiling	Water Filter	Water Purifier	Chlorine	Iodine
Giardia	good	good	good	fair	fair
Crypto	good	good	good	fair	fair
Viruses	good	poor	good	good	good

The Bottom Line

Giardia is a reasonably common contaminant, and cryptosporidum less so. The odds of encountering a virus in North American waters are very low.

Although there are never guarantees, most people use a water filter only and never experience a problem. If you're fanatical (or worried) about treatment, then boil your water. It's the simplest and most effective treatment method available.

Cryptosporidium

A protozoan that causes symptoms similar to those of giardia. If you get infected with these ugly critters, expect a bout of cramps, nausea, vomiting, fever and diarrhea. These symptoms appear 2-10 days after infection.

There is no effective treatment for cryptosporidium, but most people will manage to fight it off using their immune system. It can be quite dangerous, and a physician should be consulted for a possible antibiotic or antiparasitic medication, especially for those with weakened immune systems.

Cyclospora

A recent arrival on the water-borne disease scene, cyclospora can cause prolonged (up to six weeks) symptoms including diarrhea and fatigue. It is generally treated with antibiotics.

Viruses

Not commonly found in waterways in North America, but a real possibility when travelling outside of our continent. These nasties can include hepatitis, rotaviruses, and polioviurses. They can be handled by boiling water or treating with iodine. Water purifiers (not simple water filters) will also kill viruses.