you never know who had excess "water" and had to "drain" it up stream from you or in that pool of water to replenish the water level.
James
Yeah, and that is what is difficult in desert environments where the use of the water source is intensified by being small and in washes and canyons that concentrates the potential contaminants.
This is another great article from Backpackinglight.com but you have to be a member to read it. I have cut and pasted some highlights.
Backcountry Water Quality: Technologies, Trends and Paranoia?A close look at ways backcountry users can treat their water: what works, what should concern us, and what is hyperbole.
by Ron Silflow & Ryan Jordan | 2006-09-20
…
Should backcountry water treatment be mandatory?
Some strongly recommend, “Yes.”…
Dr. Dean Center, a physician at the Family Doctor’s Urgent Care Center, Bozeman, MT, and a frequent backcountry user speaks to the issue of water treatment from the stand point of risk assessment. “As a physician, I am much more risk averse than the unique target audience of this article. I think about disease prevention and health all the time. So, personally, I think it’s desirable to treat water. I choose to treat because I can’t reassure myself that it’s safe. …
We asked Dr. Center for his perspective on cases he sees at the Urgent Care Center that may relate to waterborne illness. “Of course it’s always difficult to sort out specific causes of enteric illnesses I see but since I’ve transitioned from a family doctor setting to and urgent care center I’ve seen some significant changes. Most significantly is the increase of Cryptosporidia infections. Whenever Giardia infection is in question, we now automatically screen also for the Cryptosporidia parasite. Cryptosporidia infections can be contracted from fruits, so it’s not limited to water as its source. Giardia, well-known as Beaver-Fever, doesn’t cause a fever. Only 10% of Giardia cases come from water sources. I’ve seen six month old infants with Giardia likely contracted from mother’s milk.
Person to person transmission of Giardia is common. The most widespread environment for Giardia infection is a daycare facility.”…
Should backcountry water treatment be mandatory?
Some say “No.”Andy Skurka is a backcountry extremist who has logged in numerous miles including a 7,712 mile trek in 339 days on the Sea-to-Sea (C2C) network of trails in North America extending from Cape Gaspe, Quebec to the Olympic Peninsula. “I almost never treat my drinking water, and I’ve never been sick due to an illness derived from a water source.”…
In general, the places that Skurka would treat his water include “areas that are swampy, near a beaver pond, where cows run freely, or in remote areas that are frequented by large numbers of people, for example, the Grand Canyon where there are lots of people and only one way for the waste to go.”…Another avid outdoor educator, Thomas R. Welch, MD, professor and chair of the Department of Pediatrics at Upstate Medical University, in an editorial published in Wilderness and Environmental Medicine, (Welch, 2004) reminds us of the 1976 incident which launched the emphasis on water-treatment technologies in reaction to a growing concern about wilderness water quality in general and giardiasis in particular. The outbreak of giardiasis among a group camping in Utah initially implicated waterborne transmission. But in retrospect, with what we now understand three decades later about giardia and the details of this case, the evidence points compellingly to hand-to-mouth transmission…
So, we asked Dr. Welch about his perspective on mandatory water treatment and he said, “The idea that backcountry water treatment is absolutely mandatory is foolish.”
Dr. Welch emphasizes, “Two problems exist with respect to our current approach to backcountry water quality, 1) though there is no question contaminated water can spread illness, this is hardly a concern unless you are talking about developing countries where people live in close proximity and consume untreated water. Even in communities where problems existed, not everybody gets disease. This indicates a definite dose response. 2) New products being marketed are certainly not harmful, however the more we emphasize technology, the more we neglect important things like handwashing.”
When asked if he was willing to say that a person can go to any US backcountry area and not treat/filter/boil their water, Welch says, “My position on the whole matter is that, since there is no real evidence that backcountry waters are a cause enteric illness in users, I rarely treat any water before consumption. As I do with everything I do in the backcountry, however, I assess the environment before taking water to drink. For example, I might treat water coming from a stream or spring whose watershed was a heavily used camping area. This would especially be the case if I were going to be staying there for a while, and consuming the water over a period of time.”
“A special case of the above would be a body of water used for extended rafting or canyoneering trips. Because of the high likelihood of fecal contamination in such settings, and since one would be drinking water from that source exclusively for the duration of his or her trip, I would definitely treat such water before consumption.”…During Dr. Welch’s frequent training sessions for group backcountry users, he illustrates the importance of handwashing by sprinkling a light powder on the hands of one member of the group. This powder is invisible to the eye except when viewed with the aid of UV light. After one day of group interactions on the trail, he pulls out the UV light source and examines the hands of all group members. The result? Inevitably, the tell-tale glow of powder appears on most, if not all group members.
“Certainly this highlights the proposal that most organisms you will be exposed to on the trail will come from hand-to-mouth transmission.”The take home message from Dr. Welch is, “While considering water treatment strategies, don’t neglect personal hygiene. For example, watch who dips their hand in your bag of gorp, and whose water bottle you share sips from. Take a serious look at good handwashing skills using either soap and water or the convenient alcohol-based gels.”
More about Dr. Welch and his expertise in Wilderness Medicine and Outdoor Education can be found at his website
www.adirondoc.com. …
ConclusionBackcountry water treatment technologies are available and effective, but are they mandatory? Ask yourself where you fall on the risk-assessment spectrum. If you are risk averse, you’re probably not reading this article. We discern no evidence that the water treatment technology manufacturers are using paranoia to hype their sales.
Keys to help you decide whether to treat or not treat should include a knowledge of 1) the organisms in backcountry water and their symptoms, 2) your own susceptibility to illness, 3) high vs. low risk water sources along with 4) a warning that despite the treatment of backcountry water, personal hygiene practices must not be ignored.
