Ingesting Giardia from your filtered water?

I’m no expert on Giardiasis, but I always thought that if you treat water taken from a backcountry stream, you were safe. By “treat” I am referring to filtering, boiling, use of iodine tablets or Aqua-Mira drops, etc.

The most recent publication of "The Catskill Canister" ran a short story about a hiker who had allegedly gotten the parasite Giardia from drinking water filtered from a Catskill stream. I use the word “allegedly” mainly because I am skeptical that this man was infected by the filtered water. Since there are many ways a person can ingest the parasite, including unsanitary “bathroom” habits, it seems highly unlikely to me that his water filter failed. In the story, however, the man states that he “can only surmise that perhaps the filter in the pump was dirty or needed replacement”. My experience with water filters is that they eventually become increasingly difficult to pump water. And that’s always been my cue to replace the filter.

So, can a dirty water filter truly cause a person to get Giardiasis? If so, should the filter be disinfected after every hike? The directions to my Katadyn filter recommends disinfecting only prior to long-term storage. Has anyone ever gotten sick after treating water in the backcountry?

Anything touching containated water can become contaminated. The inlet hoses of the filters should be kept separate from the outlet hoses. If any of the parts of the drinking system (nalgen bottle, opened lid, outlet filters, person hands, etc.) contact the contaminated water or contaminated parts that water may become contaminated.

Often people go to great lengths to filter/purify/separate hoses, 'purify' lids, etc., and then go for a dip in the river. It's hard for me to believe that some water isn't ingested while doing this. But perhaps the biggest culprit may be toilet habits, either during, preceeding, or following the trip?

'Lawn Sale' may have some good comments on this thread. Also, see the previous thread of his on this subject.

Dick

Not really too much to add, but I doubt the Giardiasis came from the water filter unless it was cross contaminated like imarchant mentioned. The only way I can see that happening with a filter is one of the ceramic ones that has been sanded (cleaned) down past the minimum diameter. Otherwise the pore size isn't changeable and will just clog before larger items such as Giardia can get through.

I'm also with rhihn on the contamination from other sources.

Lawn Sale said:

Not really too much to add, but I doubt the Giardiasis came from the water filter unless it was cross contaminated like imarchant mentioned. The only way I can see that happening with a filter is one of the ceramic ones that has been sanded (cleaned) down past the minimum diameter. Otherwise the pore size isn't changeable and will just clog before larger items such as Giardia can get through.

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Don't forget cracking from freezing.

Doug