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What about toxic chemicals in the water?
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Dimeo Train
(dimeo) - F
What about toxic chemicals in the water? on 07/31/2012 15:58:04 MDT Print View

Anyone have some thoughts, opinions, or some well researched information about the risks of toxic chemicals in natural water sources?

Water filters for backpacking don't remove chemical toxins, only the larger sized threats like bacteria and cysts. Having a water filter doesn't mean it's perfectly safe to use. Up till now, for some reason, I figured that if I had a water filter that removed bacteria I could use it to drink whenever I needed to get more water. BPL philosophy gets you thinking about avoiding the weight of carrying clean drinking water. But recently I've started asking all kinds of questions:

Should I only drink the water I carry from tested municipal sources?

How high are the risks of drinking water that is 'unsafe'?

What 'best' practices should backpackers follow to prevent drinking from chemically polluted water sources?

How remote from civilization should a water source be for it to be considered 'safe' from being contaminated by toxic chemicals?

I don't often see discussion on backpacking forums about the risks of toxic chemicals in water sources, let alone the FAQ guide. For the most part, it seems that most backpackers only appear concerned with eliminating the risks from bacteria and cysts (and sometime about BPA in bottles). Often people support claims with questionable proof, claiming "I've not gotten sick yet".

I was curious about the possibility that carcinogenic chemicals might be in the water sources where I was planning to backpack long distance. So I started looking into it more and educate myself. Locally there are trails that run several 100 miles along rivers, as well as near to urban environments. At first I had thought I might be able to use my 0.2 micron filter system so that I didn't have to carry the heavy weight of too much water on me. I've seen videos and read about hikers who only carry a liter or two, planning to filter more water at the next source. I figured that this is what I should do as well. I've also read about AT through hikers who are drinking from water sources only an hour from cities like D.C.

I contacted local and regional government environmental agencies to inquire about this. I wanted to have a better idea just how polluted the local river water is. They only said there is "a level of unknown risk", and they advise to only drink from treated and tested municipal water sources. As far as they know, the rivers and lakes along the trails were not regularly tested for any specific industrial chemicals. They said they just don't have enough manpower and funding. They said that water sources are 'recovering' from over a hundred years of heavy industrial abuse. Even if they are tested a few times a year, it's possible that by the time I'm out there filtering drinking water from the river someone can have dumped illegal waste into the water.

There are articles in the news often about pollution. Pipelines are suddenly discovered to be leaking thousands of barrels of carcinogenic gas and oil into the groundwater. It recently happened in a local provincial park, and the pipeline company estimates that 90,000 liters of gasoline leaked into the soil. The area is surrounded by farmland as well. Much of agriculture uses pesticides and fertilizers and these toxins run off and concentrate into the streams.

Then what if I carry enough water with me while I'm near cities? How remote from the city is considered 'safe' to filter water from a stream? Over a hundred miles north of the Minnesota border in the Ontario wilderness there was mercury poisoning of inhabitants and contamination of river water because of the paper and pulp industry back in the '70s. And apparently mercury doesn't just break down and disappear. Mercury concentrations in 1975 ranged as high as 5.98 parts per million. Guidelines for the safe consumption of fish is 0.2 ppm. A 1999 report from the government of Canada revealed 17,671 indigenous people had blood-mercury levels ranging from 20-699 ppb (parts per billion).

In other remote locations the mining operations pollute large amounts of fresh water producing an effluent of acids, sulphides, toxic heavy metals and more. According to the EPA the Appalachian valley waterways are affected by pollution from mining. And what about fracking? (If it sounds obscene, that's because it is.) Across the continent, oil and gas wells have been injecting chemicals into the ground and contaminating ground water. The industry claims it doesn't pollute, and the EPA studies have found benzene in ground water, which is known to cause cancer and other health problems. (An interesting article:

Here's an interesting list by the EPA of Drinking Water Contaminants ( For many it shows a goal level of zero parts per million for guidelines of what is considered 'safe'.

So aside from educating yourself, and only drinking from municipal water sources what should you do?

After hours of 'looking into it', I'm still facing a level of unknown risk if I drinking filtered water from a river when backpacking light. Just how high is that risk? Who knows? Anyone?

Your thoughts, comments, and questions on this topic are always appreciated.

Edited by dimeo on 07/31/2012 16:14:57 MDT.

Sarah Kirkconnell
(sarbar) - F

Locale: In the shadow of Mt. Rainier
Re: What about toxic chemicals in the water? on 07/31/2012 16:50:42 MDT Print View

In the US, just know where you are hiking and the history of the water. For example there are old mining areas where the water isn't safe due to trailings. But overall the water is quite safe. Tap water isn't always safe either, just saying. You have to know the source. I had a boyfriend years ago who lived next to a superfund cleanup by a Navy base, his water reeked of jet fuel. On the other hand I have stood at the headwaters of the local river (it is on the PCT near Snoqualmie Pass) and not been afraid to drink it unfiltered.....

IMO you can only worry so much.

Joe Clement
(skinewmexico) - MLife

Locale: Southwest
What about toxic chemicals in the water? on 07/31/2012 17:10:52 MDT Print View should be epa-connects-fracking-with-water-contamination-by-violating-their-own-test-protocols-in-a-study-that-won't-survive-peer-review-but-got-the-desired-scary-outcome.

Sarbars right, you're worrying way too much.

Ben H.
(bzhayes) - F

Locale: So. California
what an exhausting post... on 07/31/2012 17:43:00 MDT Print View

Can I or anyone tell you exactly the risk of drinking any water? No... and that include municipal water supplies

Oh... by the way, municipal water supplies have no way of removing those same chemicals, and they are pumping million gallons every day. Here in LA much of the water we drink comes from open water sources. When I was up in the mountains I could see the water bubbling out of the ground before it flowed down the mountain. It is ridiculous to think there was considerable industrial waste in it, because there was no industry... there wasn't even any roads.

You talked about water 1 hour from a municipality. Where does that municipality get its water? My municipality gets its water from that same stream, but they wait until it flows past housing and industry and countless places to be polluted. Then they put it into an open aquaduct that flows for hundreds of miles.

It is a good idea to know where your water comes from... but you should also have the same concern about your tap water.

drowning in spam
(leaftye) - F

Locale: SoCal
Re: What about toxic chemicals in the water? on 07/31/2012 17:59:29 MDT Print View

The PCT has at least one water source that's known to be contaminated with uranium. I still drink from it because the consequences of not drinking is higher than of drinking contaminated water.

Since you mentioned mercury, read about the Lewis & Clark expedition. Those guys put incredible amounts of mercury into their bodies. Some of those guys lived long lives. Yeah, it had some effects, but I wouldn't stress about consuming a relatively teenie tiny infinitesimal amount of mercury.

So what do I do? I know where my water sources are, try to know about the quality of water there, and plan accordingly. Sometimes I can and do carry enough water to skip an undesirable water source, but I doubt I'll ever choose to die of thirst rather than consume water with chemicals in it.

In any case, water goes downhill, hikers usually hike at higher elevations, and people usually live at lower elevations. With rare exception, water is going to pick up more and more chemicals as it goes downhill.

Hiking Malto
(gg-man) - F
Which one on 07/31/2012 19:01:26 MDT Print View

Wht water source on the PCT is contanminated by uranium. I need to know if I'm dying. Well, I guess I know I am, but anyway.

Walter Carrington
(Snowleopard) - M

Locale: Mass.
Industrial pollution. on 07/31/2012 19:06:38 MDT Print View

Most rivers in southern New England were terribly polluted with industrial chemicals and sewage until environmental laws started taking effect. I lived next to the Naugatuck River in Connecticut in the 1950s and I would never ever drink water from that river -- it had an eerie beauty, with purples, blues and greens. This area was industrialized from the early 1800s. I imagine the damage from sewage is gone, but I'm sure there is still a witch's brew of toxic chemicals in the stream bottom. The same would be true of all medium size streams in CT, MA, RI and most in VT and NH. Possibly the large rivers (Conn. River, Hudson River, etc.) dilute it enough to be safe. The same would be true of NY, NJ, and PA, at least those that pass through areas that were industrial in the last 250 years. Some of the pollutants will take forever to wash out.

The Housatonic River next to the AT in CT and MA would be an example. The current concern is PCBs from a GE factory in, I think, Pittsfield, MA. There was iron mining and steel furnaces close to the AT in CT and MA, and at least one lead mine not too far (Litchfield, CT).

Smaller streams away from the valley bottoms are more likely to be safe, but this is not a certainty. Generally, I would drink from brooks or small streams that haven't gone through old industrial towns.

There are many bucolic towns in New England that were industrial many years ago, especially valley towns. Hill top towns in New England tended to be more farming than industry. Mining did occur in New England, generally on a small scale and I have no idea how that effects water safety here.

You would need to know the industrial history of an area to guess if a stream is actually safe.

chris Nelson

Locale: San Francisco
Re: Industrial pollution. on 07/31/2012 19:58:40 MDT Print View

It is actually a very interesting topic and discussion. Sometimes I get worried about these kind things. While i'm up in the wilderness I have to think we are drinking pretty good water and I don't really worry about it. In our day to day lives we breath and ingest a lot of nasty things. Just take a look at some of your favorite local diners and dive bars. Some of those beer lines from the keg to the tap probably have not been cleaned in years if not decades!! If I worried about all the potential risks of everything in my environment I would go crazy.

But I guess you never know what is up stream...

Andrew McAlister
(mcalista) - F
Risk is overblown on 07/31/2012 20:33:42 MDT Print View

An "unknown level of risk" is CYA-speak for "We haven't tested it", rather than "it's #$%^ing close to chugging liquid mecury".

Eugene makes a good point about drinking from side brooks and streams, rather than valley bottoms. Oily stains in pools, or persistent surface foam below rapids are warning signs. Frogs are supposed to be sensitive to chemicals - if you can hear frogs, it is probably chemically safe (but doesn't mean it is bacterially safe).

Generally, it should be noticeable if you are hiking in an area where there are (former?) industrial sites. But those areas probably also have municipal supplies nearby.

Mining is the more problematic one, as you can get old mines in what are now 'wilderness' areas, and they aren't always obvious. Small scale and undocumented mines may well have used nasty chemicals (gold mines in particular can be an issue, as cyanide was (and still is) a key chemical for separating gold from associated ores).

It is worth reading trail notes and Park notes of areas you are visiting. Occasionally they will warn of particular known contaminated streams.

Open farm fields are probably much less of an issue (unless pesticide or fertilizer has very recently been applied), but you should avoid drinking immediately downstream of barns, sheds or stock yards, where concentrations can be much higher.

But in general, I think this issue is overblown for hikers. While drinking from a chemically contaminated source might be unsafe if you lived there (due to cumulative exposure), if you are drinking a liter or two and then moving on, the exposure and risk is extremely small.

Mole J
(MoleJ) - F

Locale: UK
Drinksafe filters remove chemicals... on 08/01/2012 02:22:08 MDT Print View

If you want a backpacking filter which does remove chemicals, they are available:

looks like they are trialling a product which removes radiation too.

Edited by MoleJ on 08/01/2012 02:23:03 MDT.

Steve C

Locale: sierra nevada
hear frogs water safe on 08/01/2012 08:37:52 MDT Print View

I used to survey for frogs and other critters on an Air Force base that had ground and surface water contamination due to leaking rocket fuel from cold war area missile silos.
My advice, the presence of frogs most definitely does NOT mean the water is free from contamination.