Removing chemicals

SittingBull

Russell Coight
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For removing pathogens such as Giardia and Cryptosporidium we can sterilise water by boiling for example. Unfortunately this process does not remove any synthetic chemicals which may be present in the environment due to agricultural or industrial activities. I know these can be removed by modern filtration devices, however I was wondering if there are any other low tech methods to removing chemicals from drinking water?

Do you think a simple sand/charcoal/grass etc improvised filter will do an OK job, or does the charcoal need to be activated?

Also, does anybody know about any common chemicals which may be present in the bush?

Cheers,
SB
 

Wentworth

Bear Mears
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Hi SB, I understand that the activated carbon core that some filters have, start to release the chems back into the water one they reach capacity. I think they're better suited for removing the manky taste from some water, rather than dealing with agricultural runoff. There's one manufacturer in the UK that claims their filter gets rid of all the chems, but is still be skeptical.
When we're out, we check where the water flows from on the topo, to avoid urban runoff. I'm sure a charcoal in sock filter would make the water better, but still not enough to the point where is he comfortable drinking it.
Good topic!
 

Aussie123

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I'm no expert, but I'm not aware of any low-tech methods to reliable remove chemical contaminants.

The terms activated charcoal and activated carbon are often used interchangeably and mean the same thing (unless you want to get very specific)

Normal charcoal from a fire is never going to be as effective as activated carbon (charcoal) made industrially, it has a massive surface area which makes it several orders of magnitude more effective than charcoal.

Carbon will generally adsorb organic contaminants like oils and Benzene, Toluene, some pesticides etc; it is not as effective with inorganic compounds like lead, mercury etc
I'm sure someone can say more about this ?

The problem with any homemade filter is that you can't measure how effective it is. Even if you get hold all the materials you want, can you be sure who effective it is and how do you know when it stops working ?
I think home made filters etc are fine, and depending on the water source and what actual contaminants are present, there is no reason why they won't work, but I would not like to rely exclusively on one if I had another choice available, or if I was not sure about the water quality ....


What chemicals would expect to find in the bush ?
Depends where you are !
Agricultural runoff - fertilizers and herbicides
Animal treatments - drenches, worming medicines ...
Industrial waste - the obvious runoff from active industries, but also contaminants from old mines including arsenic and mercury
Human waste - houses, or camping upstream
Runoff - from roads, forestry clearing, logging, or from other man made facilities
 

Qually

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I am not aware of any easy methods of extracting chemicals from water. I do think that it is a very important thing to talk about, especially for new bush crafters/campers. The good and bad sites for chemical pollutant issues and how to avoid them. Maybe a separate thread for best practise.
 

SittingBull

Russell Coight
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Thanks for the great responses guys.

From the basic google research I've done myself it was clear that there was no easy answer. That's why I thought I'd ask here.

You've all given me a lot to think about. I suppose its basically a matter of avoiding contaminated areas. I find it so frustrating that some areas have been polluted but I suppose thats the price we pay for all the creature comforts of modern society.
 

Aussie123

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Not usually practical but you could distill the water.

I just found this.
......
Distilling will work well for sea water, (as in the video).

Distilling won't necessarily remove all contaminants (particularly some of the organic compounds).

Think about it this way ... if you has a river which was contaminated with C2H6O and you distilled a bucket of it, you'd end up with a cup of C2H6O, not a cup of H20 !
(Just KISS for purposed of explanation - OK ?)

C2H6O is alcohol and if you distill a mix of water and alcohol, you will get an alcohol concentrate - that's how spirits are made !

The same principal applies to other organic (and some inorganic contaminants) like some pesticides / fertilizers. By distilling them, you may end up with concentrated contaminants, rather than water.

My point here is that you need to know the contaminant in order to know how to remove it.

I know that "most" of the streams I use are from relatively clean sources, so boiling is sufficient to sterilize any "bugs" and make it suitable to drink.

If the water source is from an agricultural, or industrial area .... its tricky !
 

Havamal

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This topic is right up my alley. I’m a hydrogeologist and specialise in the design and construction of water treatment systems.

Whilst the scientist in me could talk about water treatment for the next week I will keep it pretty basic. The following ideas are a summary of what I’ve learnt in the last 15 years on the job and also from 25 years of treating water in the bush.

I will leave specific brands of gear for a later post…This one is just about the science.


Objective: To make water safe to drink
Produce water as palatable as possible
Keep weight to a minimum
Adopt a water treatment method that is reasonably quick

Preamble:

“Fast and Light” is really the essence of bushcraft. We want to use our skills and knowledge rather than carrying bulking technology. I see people all the time carrying 5 litres of water when bushwalking because they weren’t sure what the water situation was like. That’s 5kg. I would never carry more than 2 litres and generally its less than 1 litre. Why? Because I know how to find water and make that water safe and palatable. 4kg less on my back makes me move faster with less energy used. Travelling light I can maintain 6km/hr verses the heavy pack bearing bushwalker with 5 litres of water who averages 3km/hr. This means that If I move for 2 hrs and cover 12km I could then stop for 3 more hours to rest, fetch water and treat it and still be in the same position as the weighed down bushwalker.

My point is that we are crafty people….so lets get our water craft squared away.

There are three types of treatment available to us
1. Heat
2. Chemical treatment
3. Filtration

No one method will make any water both safe to drink and palatable in every situation. Boiling is pretty good as is chlorine or iodine treatment but it will not remove sediment or taste and may even make the taste worse.

So it comes down to figuring out the water quality and treating accordingly. Let one methods weakness be covered by another’s strength.

Note: While in this post I’m really talking about short term (1 – 14 days) of water treatment the principles apply to long term subsistence. In an off grid life style then water boiling is a key daily task and filtration can be done using both sand and charcoal media which can be found in the bush and resupplied as required.
 

Havamal

Les Stroud
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Heat
So we all know that if you boil your water you can drink it. Pathogens start dying at around 70 degrees C and at 100 degrees C (boiling at sea level) everything is dead. The old rule of 3 minutes rolling boil is good however most micro organisms die during the path from 70 to 90 degrees. The rolling boil at 100 degrees C just finishes off the stubborn few. So I go with a moderate heat with a progressing temperature range to boiling, followed by 1 minute rolling boil and its done.

Outcome: Safe drinking water that will not make you sick. Depending on the source it may still smell and/or taste bad and may be full of dirt and detritus. No matter the taste the water is safe.


Chemical Dosing
Generally the two types of chemical treatment – iodine and chlorine.

Chlorine works better on E Coli than iodine
Iodine works on Giardia but Chlorine does not.

The fact that chlorine doesn’t work on Giardia has always been the deciding factor for me. Iodine wins.

Outcome: Safe drinking water that will not make you sick. Depending on the source it may still smell and/or taste bad and may be full of dirt and detritus. No matter the taste the water is safe. The advantage of chemical treatment is that while it is working on the water you can be moving to your next stop rather than tending to a fire.


Filtration
Micro organisms are all different sizes. But no matter what the manufacturer says there is no hand operated filter that will remove all micro organisms. The small ones are so small that they can pass through the filter media.

Filtration should be seen as a way of improving the look and taste of water. Boiling or chemical treatment renders the water safe to drink but if you cant stomach the taste or smell it’s pretty pointless.

Fibre, ceramic or activated carbon?
Filters use different filter media. Fibre and ceramic (and sand in larger units) will take out solids but not chemicals, taste and odour, but activated carbon will. Best solution is a two stage filter that has ceramic or fibre filtration followed by activated carbon. The added benefit of the activated carbon is that it will remove excess water treatment chemical like chlorine and iodine. It also removed volatile organic compounds (VOCs). The water will be gin clear and taste like Evian.

pH and dissolved heavy metals will be unchanged by filtration. The only way to manipulate these is via the addition of acids and alkalis.


So that’s it. Water Treatment 101. I’ve made a small printable table below. Select the water type (clear or dirty) and the availability of fuel (ample or limited) and it will suggest the best treatment sequence.
 

Wentworth

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Hi Havamal. Thanks for the info.
Do you have any studies about the chlorine being ineffective against giardia? Aquatabs website claim that it is effective, though they don't specify whether in the oocyst stage.
 

n5750547

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What do you guys recon of the Sawyer water filters? I know they won't take out chemicals but people in the states seem to rate them highly.
 

Aussie123

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I have one, but have not used it extensively (its relatively new).

The filter seems to do a good job and the specifications are very impressive;
however I find it a bit awkward to fill the soft pouches which come with it - so I've used a small PET water bottle (500ml disposable type), which seems to work for me.

I know some people have devised some cunning methods to get the water through them, but for me the PET bottle (or the pouch) is the best / simplest so far.
 

n5750547

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I have one, but have not used it extensively (its relatively new).

The filter seems to do a good job and the specifications are very impressive;
however I find it a bit awkward to fill the soft pouches which come with it - so I've used a small PET water bottle (500ml disposable type), which seems to work for me.

I know some people have devised some cunning methods to get the water through them, but for me the PET bottle (or the pouch) is the best / simplest so far.
I ordered the Sawyer Squeeze which came with a 64, 32 and 16 oz bag (from Survival Supplies Australia who I would highly reccomend) and I probably wouldn't bother with any but the 64 bag. The others are a bit fiddly for how much they can hold. I used it yesterday and today so and I think it worked but I guess I will know for sure in a few days if I'm still feeling ok
 

TasMonk

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This is a very good question! I know that down here in Tassie there are scores of contaminated waterways in the bush. The last total I heard specified 70, if I remember correctly, known to be contaminated. The majority of this contamination comes from old mining sites, some of them unused in a hundred years. The mine sites themselves are completely grown over and forgotten by all but a tiny few. Yet still the chemical contaminants from the mines' active phase are appearing in the water. Unfortunately I haven't yet tracked down a list or map specifying which waterways are testing positive for contaminants so I always wonder a bit what I might be drinking.
 

Hairyman

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With an improvised carbon filter, maximise the contact time, batch your water to be treated in a billy and add as much crushed
charcoal as you can, mix and leave for ten minutes plus, then strain. Flow through improvised filters are probably too
quick to remove much toxins.
Common toxins encountered in surface waters are those from various cyanobacteria (blue-green algae).
Treatment to remove these include good contact time with activated carbon and ( mainly for stock) treatment with
higher doses of chlorine. Just boiling doesn't remove these toxins.
The more steps in treatment you use the more risk is reduced.
 
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