
Filtering stream water or fresh water is medically unnecessary - curtis
https://slate.com/technology/2018/02/filtering-stream-water-or-fresh-water-is-medically-unnecessary.html
======
benjohnson
Don't follow his advice: All it takes is a rotting animal carcass or infected
human poop near your water source to render water unfit for consumption.

Explosive diarrhea and crippling intestinal craps would be a disaster when
your miles away from civilization.

Millions of people in the third world die from infected water sources - my
church spends millions to help them setup small water filter factories (and
setup the economy around it) and it's estimated that $250 in funding helps
save one person.

~~~
hyperbovine
The article nails the phenomenon on the head -- the "outdoor community" tends
towards wealthy and educated -- but then completely whiffs on the obvious
deduction. Viz., getting sick from waterborne pathogens carries an opportunity
cost that is far higher than the price of a filter. I've had such an illness
-- from using a malfunctioning filter in a place where it was really
necessary, no less -- and it suuuucks. I'd happily pay $100-200 to not have to
deal with that again.

~~~
beamatronic
How could you have protected against a malfunctioning filter?

~~~
yjftsjthsd-h
Multiple filters in series, ideally varying manufacturers?

~~~
AstralStorm
You mean more manual labour filtering presumably filtered water again?

These filters are rarely electric and typically hand operated and partly
chemical. (Electric filters tend to fail when you really need them.) Or just
heat and apply UV light to water.

~~~
yjftsjthsd-h
That's exactly what I mean:) The stated problem was getting sick when a filter
didn't do its job. The question was how to avoid being infected when a filter
(silently) fails. My answer is redundancy. This is more expensive in time,
money, and effort, but does mean that a malfunctioning filter doesn't mean you
get infected.

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zekevermillion
Anecdotally, I've had gallons of water from lakes in Northern MN while
camping, and it was delicious. On the other hand, also anecdotal, one of my
ancestors in Germany is said to have died from infection after drinking from a
pond in Germany. More recently, a family friend became seriously ill after
drinking from a mountain stream -- they think it may have been due to a dead
animal upstream from the location. The rule-of-thumb I was told is to take
water from the middle of the lake, and not near or downstream from any streams
that might feed into it. I wonder if this article is perhaps understating the
risk, or maybe giving people ideas that could lead them to engage in
potentially life-threatening behavior, particularly if they are not
experienced in back country survival. Yes it is often OK to drink from fresh
water sources, but it is not a myth that people get very sick and/or die from
it.

------
jly
Water filtration may be mostly unnecessary, but water purification
(elimination of gut-crunching pathogens) is another story. If you're in a true
survival situation, taking a chance on drinking water that could have
dangerous pathogens is probably not worth the risk. Every water source is
different and carries a different risk profile (how far upstream, where the
water is sourced, etc).

You don't need to buy anything to purify water. Oddly this article did not
discuss the simplest method of all - just boil it. A steel, non-insulated
water bottle works fine.

~~~
dwyerm
You don't even have to boil it, technically. Most pathogens die at a much
lower temperature, given enough time.

For what it is worth, our backwoods trip had us looking for clear, running
water that had a small amount of green stuff growing in it, on the theory that
if it wasn't killing greenery, then it wasn't killing you. Then, a treatment
with off the shelf iodine tablets. No filtering needed. The iodine added an
unpleasant taste, but I thought that was better than the gut-crunching
alternative.

[http://www.who.int/water_sanitation_health/dwq/Boiling_water...](http://www.who.int/water_sanitation_health/dwq/Boiling_water_01_15.pdf)

------
JoeAltmaier
I've met a backpacking couple who never filter. They fill their water bag from
any deep source (lake or river) by swimming out, diving deep and filling the
bag there. Because they believe most organisms live in the top few inches.
Worked for them; a decade of backpacking all over the world.

On the other hand, one of our Scout leaders got giardia at Boundary Waters,
due to incorrect filtration habits. So the article claiming no correlation
exists may be an exaggeration.

~~~
semi-extrinsic
In Norway, where statistics show about 80%(!) of the population go hiking in
the mountains at least once a year, almost nobody uses a filtration device.
And we don't all get sick. Official advice is that drinking from streams is
fine when you're not downstream from human habitation or livestock grazing
areas.

~~~
mmagin
Or these relatively cold streams harbor few parasites evolved to thrive at
human body temperatures -- I would not carry this practice to warmer areas of
the world.

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soyiuz
The article vastly overstates it's conclusions to dangerous effects. A cursory
search of medical literature finds plentiful epidemiological evidence. Cases
of water borne sickness are not infrequently reported all over the country.
One cannot rely on visual clues alone to confirm absence of human or
agricultural activity nearby. Worse yet, backcountry hikers may quickly find
themselves in a life-threatening situation even after a mild injury or
persistent symptom, like diarrhea. A twisted ankle is no big deal in the city,
but a serious medical emergency when you are on top of a mountain.

One does not have to buy the hype of big filter---just boil your water or use
iodine to stay safe.

------
rrrazdan
As someone who got Hepatitis A from drinking from a mountain stream in deep
Himalayas ( however deep you go in India you always have someone above you
shitting in the water), I always carry an Iodine tablet with me now.

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tbranyen
Water filtration straws are cheap and easy to use. There is no reason for the
risk, especially not while out in the wilderness.

~~~
nxsynonym
Agreed. Filtration systems are cheap, and even if you don't have one with you
it's pretty easy to boil water to be sure.

In the extreme case that you can't boil the water, try collect rain water or
water closest to an in-ground source (top of a stream where it comes out of
the ground or a natural spring).

The biggest risk factor imo (outside of personal hygiene) is not knowing what
lies further upstream. Only takes one dead animal to make you have a real bad
time.

------
Someone
…most of the time.

 _" The idea that most wilderness water sources are inherently unsafe is
baseless dogma"_ may be true, but if you only need to hit one sometimes unsafe
source at the wrong time to be in trouble.

------
macNchz
I’ve been a big outdoors person all my life and regularly go backpacking and
drink mountain stream and spring water. I’m also a big advocate of being
realistic about risks and not sweating stuff that’s scary but extremely
unlikely.

That said, I know people personally who have had giardiasis. It’s awful. On a
typical backpacking trip I’ll get water from from a bunch of different sources
along the way, often not knowing what’s upstream. A few seconds of stirring my
water with a lightweight UV sterilizer pen which I bought for $60 years ago is
relatively low cost insurance against a risk which is hard to assess in the
moment.

My understanding is that much of the research on giardia et al has been in a
few specific wilderness areas, and widespread sampling studies of many water
sources are fairly few, so using what little research does exist to inform my
decision to drink directly from a random mountain stream seems dubious.

------
shadowtree
Someone tell Nikolay Przhevalsky that his cause of death was not linked to
drinking from a stream:
[https://en.wikipedia.org/wiki/Nikolay_Przhevalsky](https://en.wikipedia.org/wiki/Nikolay_Przhevalsky)

Just need a dead animal a bit upstream and you get a lot of goodies.

~~~
throwaway2048
a filter wouldn't have helped any, they dont protect against bacteria.

~~~
tzs
Bacterial removal depends on the size of the filter. Microfilters remove many
bacteria, including Campylobacter, Salmonella, Shigella, and E. coli.

Ultrafilters do most bacteria (and many viruses).

See [https://www.cdc.gov/healthywater/drinking/home-water-
treatme...](https://www.cdc.gov/healthywater/drinking/home-water-
treatment/household_water_treatment.html)

Lifestraw, for example, does 99.9999% of bacteria. See
[http://www.lifestraw.com/faqs/](http://www.lifestraw.com/faqs/)

------
M_Bakhtiari
Someone tell these guys it's cool, they can ditch their straws:

[http://www.slate.com/articles/health_and_science/medical_exa...](http://www.slate.com/articles/health_and_science/medical_examiner/2015/03/guinea_worm_eradication_nylon_filters_and_caring_about_others_bring_a_public.html)

~~~
LastMuel
The article specifically states that it concerns areas not trafficked by
humans and pack animals.

The people in your linked article would likely still need to take additional
precautions.

~~~
M_Bakhtiari
I'm mainly complaining about the American world view of everyone on the
internet being other Americans within the borders of the United States. Take
eBay for instance, with the majority of American sellers flat out refusing to
ship internationally, even to western Europe.

I get that they don't want to sell me yellowcake, but I don't see the harm in
sending me a few obsolete computers from the 1980s.

~~~
floren
They refuse because it's a pain in the ass to ship internationally and there
are probably plenty of buyers in the US.

~~~
M_Bakhtiari
Wherein lies the pain of shipping internationally from the US?

Whenever I've shipped stuff, whether through the regular postal system or the
big name couriers, they don't seem to care where in the world the recipient
is, other than that different places call for different rates, which I suppose
is fair. And eBay accounts for this too.

------
MikeBVaughn
OTOH, I'm perfectly okay paying REI $40 once every few years to not verify
this.

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MaxBarraclough
> To be clear, there’s no question that Giardia lamblia, Cryptosporidium
> parvum, and various strains of fecal coliform bacteria—the waterborne
> pathogens responsible for giardiasis, cryptosporidiosis, and other
> diseases—can infect humans, with potentially serious health consequences.
> Yet research to date has failed to demonstrate any significant link between
> wilderness water consumption and infection with these threats.

So what vectors are there for those threats, if not unfiltered 'wilderness
water'?

~~~
arethuza
I've wandered the Scottish Highlands for many years camping and using bothies
never filtered water - mind you I mostly consume coffee or tea so maybe the
small amount of boiling killed off any beasties. Mind you - I am fairly
careful about where I get the water (check for any dead animals upstream,
don't take water from anywhere that is obviously frequented by animals or
people).

Meanwhile, my wife got a nasty case of cryptosporidium - GP suspected it was
from a swimming pool!

~~~
DarronWyke
Boiling is what did it. Boiling is the most sure-fire way to disinfect water.

~~~
AstralStorm
Unless contaminated chemically, e.g. by heavy metals. Most portable filters do
not protect against these though.

~~~
DarronWyke
Most portable filters will, actually. They've got fine enough filters to catch
protocysts; they'll easily catch any metal contamination. What they don't get
are smaller bacteria and virii, which is where secondary purification in the
form of boiling or purification tablets is necessary.

------
PacketPaul
Anecdotally evidence: I've been backpacking for 25 plus years and am an avid
filter user. But I have met dozens of people who do not, almost all on the AT
(where I backpack the most). In the 90's it was quite common to find thru-
hikers not using a filter. I have never met anyone who got sick from
unfiltered water.

Will this change my behavior. Probably not. But I will stop treating my
contaminated side of the filter like it it covered with ebola.

~~~
robotresearcher
You should avoid that contamination. The raw water does contain bacteria, just
in low enough doses for your immune system to handle it. You have deliberately
concentrated days worth of bugs in a small spot, so it’s likely to be nasty.

~~~
yourapostasy
Would UV light help mitigate that small spot's infectiousness?

After reading this thread, I'm writing to MSR about whether treating their
Guardian filter with my ozone generator in a small box to 1 ppm for half an
hour after I get back would void their support. I don't touch it now, but I'd
rather kill the bugs than leaving them to desiccate in storage.

------
lolsal
What does the phrase 'medically unnecessary' really even mean? Does it mean
'not necessary to filter your water except in those cases where it is
necessary to filter your water'?

I think the article is saying the risk of a problem is low, so it's not
necessary to filter. That's a silly statement to me and seems totally
subjective, not objective. I'll decide how averse I am to risk, given the
costs involved.

~~~
AstralStorm
1 in 20 is not low odds at all. Ask any D&D player.

~~~
lolsal
Are you sincerely arguing that a 5% chance of something happening is not a low
chance? Either way I don't really feel like arguing about relative chance.

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rhombocombus
If I see it come out of the ground I have zero issues drinking unfiltered
water. With a filter I prefer streams first, lakes second, and ponds last in
terms of preference. I have made exceptions at high altitude and drunk from
streams without a filter, but the idea of crippling diarrhea 20 miles from
anything is frightening, and boiling water isn't always convenient on long
trail days.

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jeffdavis
Most of the time, Russian Roulette is perfectly safe. But sometimes it's very
dangerous.

------
mod
There's a rebuttal that was posted a few days after this, here's the HN link:
[https://news.ycombinator.com/item?id=16320964](https://news.ycombinator.com/item?id=16320964)

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hashkb
So I'm addicted to the flavor of iodine tablets for nothing?

------
curtis
The recommendation for survival situations is to purify, treat, or boil your
water if you possibly can. If you can't, then you should consider drinking
water without processing, the theory being that it's better to get sick with
something that probably won't kill you in 3 days rather than die of
dehydration in the next 12 hours. The calculus changes quite a bit if the
unprocessed water likely won't even make you sick.

~~~
AstralStorm
Depends on the situation. Generally in temperate climate you wouldn't dies off
dehydration in 12h of even quite strenuous work. A day is typically survivable
and you would have quite a range to reach something potable or appropriate
hardware.

Now, if you went on a trip in sunny climate, you're in luck as UV can be used
to disinfect most containers. Does not take too long.

In very cold climates frozen rainfall (snow, ice) is an excellent source of
water if you can melt it.

The highest risk is tropics, as high temperature, humidity and lack of
sunlight make obtaining potable water or purifying it difficult, so unless you
know which watery plants to eat you might be in serious trouble.

