I'm with asmrz. If you have ever had giardia, you will filter your water. I was a tough guy and lived with giardia for many years before I realized the long term effects on my intestines was unacceptable.

I wrote a forum post many years ago about a giardia episode, but it must have been flushed away by some SP forum cleanse. Wonder if Matt could find it in some archive for reposting.

Funny thing about giardia, all the people I know who have had it are very prolific hikers who drank from springs and clear streams.

So, I'm with Chad too and this apart from my general physical attraction to him. Apart from the fact that I've rarely filtered water unless it seems funky (then I use iodine and vitamin C to neutralize the iodine) I read an article years ago in the LA Times outdoor section that highlighted a detailed testing of over 100 water sources throughout the Sierra (streams, rivers, lakes and tarns) over some time that all but one tested completely free of Giardia and even then in an amount that could not get one sick. Then you must consider that not everyone can even get Giardia very easily. Many have a much higher tolerance than others and could be exposed to even higher levels of the parasite with no issue. You should not go to the mountains as the drive to the mountains or the tuna at that Subway in Independence are likely to do you far more harm than the unfiltered water.

... it has little to do with a bacteria like Giardia

Giardia lamblia is a protozoa, not a bacteria.

JHH60 wrote:Giardia isn't the only nasty thing that can be found in contaminated water, so arguing about whether you should treat water based only on whether giardia cysts may be present is a like saying you don't have to wear a condom if you think your sex partner is most likely HIV negative.

+1.

Anyway, everyone should always hike with a protective dress, it is very useful if you get raped by an STI infected bear.

Is the Hanta virus able to be spread through water?

I think there will allways be people who agree or disagree. I think if I were new to this (SP) activity, I would seek information, not attitude. This one, like other posts are for the new people to make up their own minds, it's not for me to provide winning and "gotcha" statements on a public forum.

BTW Last summer Penelope and I had the "privilage" (never again) to walk by the Trail Camp on Whitney. I have never seen so many feces in discarded bags and out of bags and in the open in my outdoor life. The (well intended) feces bags program doesn't work that well if the bags get discarded along the trail. There are other places in our beloved Sierra that look and smell like "Sheet"too. Just too many people, totally different than 40 years ago. The water flowing from these places must be "really good". I would suggest severe caution when pondering how clean the water is in the Sierra, especially some frequently visited places.

Of course some of us never go where other people go, in the Sierra, Tetons, Rockies and other places, so no worries. You decide..

If it's clean flowing water with little human traffic above it I'll drink from the stream, however if I'm in a heavily trafficked lake I'd prefer to use a filter. I just don't fancy the idea of two weeks of green, foamy, explosive diarrhea, no matter how small the risk. I suppose it's the same idea as wearing a seatbelt. I certainly wouldn't begrudge anyone who uses a filter 100% of the time, either.

This is a topic of interest to me. As a veteran of giardia I got in the Sierra, I am back to treating all water. Personally, I usually use Aqua Mira drops.

mrchad9 wrote:...It might also interest her to know that every camper in Tuolume Meadows campground plus all the lodges up there and the ranger station use unfiltered water from the Dana Fork of the Tuolumne River...

Are you sure about that?

The Tuolumne Meadows Water Treatment Facility is located in the Tuolumne Meadows District of the Park. The water plant is a National Park Service (NPS) owned facility and permitted to produce domestic water by the California Department of Health.

asmrz wrote:...After you get it the first time, you will look into this (I guarantee it).

Isn't that the truth!

mrchad9 wrote:...I just haven't seen a single study that shows an unacceptable level of pathogens in any water anywhere in the Sierra, much less the backcountry...

Now, after 10 years of fieldwork and 4,500 miles of backpacking, Derlet knows for sure. What he has learned, after analyzing hundreds of samples dipped from backcountry lakes and streams, is that parts of the high Sierra are not nearly as pristine as they look. Nowhere is the water dirtier, he discovered, than on U.S. Forest Service land, including wilderness areas, where beef cattle and commercial pack stock — horses and mules — graze during the summer. There, bacterial contamination was easily high enough to sicken hikers with Giardia, E. coli and other diseases.

Read more here: http://www.modbee.com/2010/05/08/115893 ... rylink=cpy (I think that's how I got giardia in the High Sierra, drinking from a beautiful brook that had no sign of cattle in the area until I walked farther.)

fedak wrote:There was a study at one point that found that there was less Giardia per volume of water in the top foot of high altitude lakes than there was in the SF tap water..

Sounds like you are paraphrasing the Rockwell paper. San Francisco water is run through a modern treatment plant using UV, chlorine and chloramine and is at least a thousand times safer than mountain water (in regards to waterborne diseases) because of it.

This Rockwell chart is extremely misleading:
~1000 Typical swimming pool contamination Swimming pools are heavily chlorinated at a level that quickly kills giardia. Plus I'm not chugging swimming pool water.
~100 Giardiasis is plausible Plausible? 100% of people got giardia at that level when tested.
~10 Minimum needed to contract giardiasis False. Ingestion of one or more cysts may cause disease http://www.fda.gov/food/foodsafety/food ... 070716.htm
~1 Some wilderness water outside California Yes, and some sources have 20 or more.
0.12 Some San Francisco water The most recent report is 0 to .07 BEFORE it enters the water treatment plant. It would be less than .00007 in tap water.
0.108 Worst Sierra Nevada water. False. That may have been the worst water they tested in the relatively few samples they did 30 years ago, but giardia is commonly found in the Sierra and as such there will always be some pulse contamination where there are spikes in cyst concentrations.

"Several backpackers appear weekly at Centinela Mammoth Hospital in Mammoth Lakes sick enough with giardiasis to need urgent care," said Dr. Jack Bertman, an emergency physician, who noted, "We publicize it a great deal more in Mammoth." http://articles.latimes.com/1988-07-26/ ... re-program

People should make their own risk assessments, of course, but there is a lot of misinformation out there from both sides.

Alaska wrote:This is a topic of interest to me. As a veteran of giardia I got in the Sierra, I am back to treating all water. Personally, I usually use Aqua Mira drops.

mrchad9 wrote:...It might also interest her to know that every camper in Tuolume Meadows campground plus all the lodges up there and the ranger station use unfiltered water from the Dana Fork of the Tuolumne River...

Are you sure about that?

The Tuolumne Meadows Water Treatment Facility is located in the Tuolumne Meadows District of the Park. The water plant is a National Park Service (NPS) owned facility and permitted to produce domestic water by the California Department of Health.

asmrz wrote:...After you get it the first time, you will look into this (I guarantee it).

Isn't that the truth!

mrchad9 wrote:...I just haven't seen a single study that shows an unacceptable level of pathogens in any water anywhere in the Sierra, much less the backcountry...

Now, after 10 years of fieldwork and 4,500 miles of backpacking, Derlet knows for sure. What he has learned, after analyzing hundreds of samples dipped from backcountry lakes and streams, is that parts of the high Sierra are not nearly as pristine as they look. Nowhere is the water dirtier, he discovered, than on U.S. Forest Service land, including wilderness areas, where beef cattle and commercial pack stock — horses and mules — graze during the summer. There, bacterial contamination was easily high enough to sicken hikers with Giardia, E. coli and other diseases.

Read more here: http://www.modbee.com/2010/05/08/115893 ... rylink=cpy (I think that's how I got giardia in the High Sierra, drinking from a beautiful brook that had no sign of cattle in the area until I walked farther.)

fedak wrote:There was a study at one point that found that there was less Giardia per volume of water in the top foot of high altitude lakes than there was in the SF tap water..

Sounds like you are paraphrasing the Rockwell paper. San Francisco water is run through a modern treatment plant using UV, chlorine and chloramine and is at least a thousand times safer than mountain water (in regards to waterborne diseases) because of it.

This Rockwell chart is extremely misleading:
~1000 Typical swimming pool contamination Swimming pools are heavily chlorinated at a level that quickly kills giardia. Plus I'm not chugging swimming pool water.
~100 Giardiasis is plausible Plausible? 100% of people got giardia at that level when tested.
~10 Minimum needed to contract giardiasis False. Ingestion of one or more cysts may cause disease http://www.fda.gov/food/foodsafety/food ... 070716.htm
~1 Some wilderness water outside California Yes, and some sources have 20 or more.
0.12 Some San Francisco water The most recent report is 0 to .07 BEFORE it enters the water treatment plant. It would be less than .00007 in tap water.
0.108 Worst Sierra Nevada water. False. That may have been the worst water they tested in the relatively few samples they did 30 years ago, but giardia is commonly found in the Sierra and as such there will always be some pulse contamination where there are spikes in cyst concentrations.

"Several backpackers appear weekly at Centinela Mammoth Hospital in Mammoth Lakes sick enough with giardiasis to need urgent care," said Dr. Jack Bertman, an emergency physician, who noted, "We publicize it a great deal more in Mammoth." http://articles.latimes.com/1988-07-26/ ... re-program

People should make their own risk assessments, of course, but there is a lot of misinformation out there from both sides.

Shhh.......reason and studies that show the opposite are not allowed here. Let 'em get the runs.......

Well yes some people do get it. Those sensitive should take precautions. And there are a number of ways to get it. In the mountains only a fool drinks water where cows and horsies graze. Actually most coming down with the disease are urban kids and they aren't getting it in the mountains. Snippet from this link:

http://usatoday30.usatoday.com/news/hea ... rvey_N.htm

Harris also conducted 1,001 telephone interviews. Among findings:
•Overall, 92% of people report always washing their hands after using a public bathroom, but only 77% were seen to do so.

So yes indeed a quarter of us that squat down in public restrooms then if no one else is there to watch, walk right out. Same thing shows every time such polls are taken and some places it is much worse.

So one day 25% Billy gets a job at B&B, a burger and burrito shop along US395. The restaurant manager Douglas is a rather considerate small business person and carefully instructs all his employees about the importance of handling food carefully. On the job Billy is always careful handling food and washing his hands out in the kitchen where everyone can see him working...butt when he is alone in the restroom where HE knows no one is watchin, well lets say he does most of the time depending on how he's feeling. And this morning Billy had a tummy ache...Wahhh! So that same lucky day Rupert is driving from LA on his way to the mountains to climb Mount Studly and stops in at the B&B shop. And well Billy just did a you know what and didn't to do you know what, and now he grabbing some lettuce in the kitchen. Later on the scramble up to the staging base of Studly Coulour, Rupert fills his nalgene bottle full of fresh mountain water at the usual willow spring. A couple weeks later back at home Rupert has a problem...

Knew this rather recent report was somewhere so tracked it down. Everything about giardria statistics one ever needs to look at. Of note, we California and Nevada folk are near the lowest on the chart list.

http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6105a2.htm

Just did receive one of these 2 ounce straws from Amazon because yes I do occasionally find myself thirsty about places in the mountains where cows lift their tails...

http://www.amazon.com/Vestergaard-Frand ... ter+filter

Those sensitive should take precautions.
Presumably the only way to determine that is by getting it? We've already seen on this thread how people can go for decades before their luck runs out.

In the mountains only a fool drinks water where cows and horsies graze.
There are numerous accounts including mine, where the area showed no sign of grazing where water was gathered, but in fact stock had been grazing upstream, with the result being a case of giardiasis.

Here's a quote from the CDC:
Giardiasis can be spread by:
•Swallowing Giardia picked up from surfaces (such as bathroom handles, changing tables, diaper pails, or toys) that contain stool from an infected person or animal
•Drinking water or using ice made from water sources where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
•Swallowing water while swimming or playing in water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
•Eating uncooked food that contains Giardia organisms
• Having contact with someone who is ill with giardiasis
•Traveling to countries where giardiasis is common

Note that the number of people from which we can catch giardiasis from plummets in the mountains of the U.S. The risk factors that INCREASE dramatically are the 2nd and 3rd, drinking or swallowing untreated water. High infection rates occur in hikers and backpackers in the United States. Giardiasis is a common infection in active outdoors population because of their exposure to areas inhabited by infected wild animals and ingestion of free flowing water which may contain cysts. http://www.stanford.edu/group/parasites ... diasis.htm

The raw giardia stats before extrapolation will usually dramatically underestimate the true rates. In fact, there are only about 20,000 cases a year reported yet an estimated 1.2 million cases occur annually. For example, in the post above where the physician reported multiple cases of giardiasis per week in Mammoth, California, there were NO cases OFFICIALLY reported in that county, Modoc, for 2008-2010.

A study showed that backpacker's hands were actually cleaner in the field than they were heading into the field. http://www.adirondoc.com/publications/h ... n_2012.pdf

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Here we go again, the big debate about water safety in the wilderness. Having worked in medicine, I can say that giardia is not entirely understood. The presence of giardia in the gut does not confirm an "infection" as many animals including people can have it and not know the difference, and that is partly why even diagnosing giardia can be of a dubious nature. Infectious disease folks generally agree that Individual susceptibility is immune related and dose dependent. Never had a problem myself, and I believe it is true for the vast majority, but it only takes a few bad cases to have everyone scrambling to cover their ass, as does the NPS. Honestly, in today's litigious society, how can you blame them?

One common recurring note I'm reading is that clear running water is safe, and on that I disagree. As noted earlier, there can be far more than girardia lurking in those otherwise pristine looking waters! Streams don't filter, it is that simple. And because the water is turbulent, the sun's UV radiation can't do much to disinfect. Granted, if the water is coming directly out of the ground as with an artesian well, then it is safe as natural water can be (assuming no nearby toxic waste dump has leached into the ground water). One other scenario where I'm confident in water safety is when the source is a mountain lake above 10,500 feet where the surface water is nicely irradiated. Otherwise, I pull out my nifty Steripen and take 90 seconds to treat one liter. Never had giardia (or anything else that can cause one to shed their gut lining) and don't see the harm in a bit of precaution and common sense.

I went almot 10 yrs w/o filtering water, but did eventually get a parasite. And, it wasn't giardia. Also, the symptoms were more mild and built up over time, making it much harder to figure out the cause. Something to think about. Everybody is focused on giardia and think they're going to get something common whose symptoms will be obvious. There are other types of "bugs" you can catch, even if somewhat rare.

These days with all the new fancy filters it just seems a lot easier to filter the water and avoid the 1-2 yrs of gastrointestinal distress.

peninsula wrote:One other scenario where I'm confident in water safety is when the source is a mountain lake above 10,500 feet where the surface water is nicely irradiated.

That's pretty much all I drank from and stil got the parasite I mentioned above. It's possible I didn't even catch it from the mountains, but it sure seems like the most likely spot.