I've been hiking, camping hunting and fishing in the Washington Cascades since 1957, and I contracted giardiasis wheh I was about 17. Sick as a dog for three months until it was diagnosed. Antibiotics put it down in about four more weeks.

I now either filter or boil any water I drink. At altitudes over 3000 feet water doesn't get quite as hot, so I always boil water for about five minutes, longer simply wastes fuel. A good filter works better, but is slow. I use a siphon system that filters about 1/2 gallon an hour.

Giardia Lamblia cysts are too small to see and quite comfortably survive freezing for very long periods (500 years and more) but succumb to boiling in minutes. Clarity and speed of water flow are irrelevant, as is aeration. Gamble if you will, but if you ever get the real thing expect to be very ill for a long time.

Diagnosis is tricky and treatment slow. The symptoms are like having severe stomach flu for weeks on end, with fever, severe muscle aches, nausea, vomiting and bad stomach cramping. It is not fun, trust me.

Nordicthug