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  #1  
Old 02-05-2011, 11:27 PM
sweeteviljesus sweeteviljesus is offline
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Is rainwater safe to drink?

I would not expect fresh rainwater to have any biological impurities, but what about chemical impurities? Have decades worth of antipollution measures made that a moot point?

Thanks,
Rob
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  #2  
Old 02-06-2011, 12:23 AM
madmonk28 madmonk28 is offline
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There are a lot of variables including how it was collected. Has it landed on a roof and flowed through a gutter to a collection point? Weather conditions can have an impact as well. I am by no means an expert, but I've worked on water sanitation projects in the developing world and it is usually recomended that rain water be used for irrigation and washing, not drinking. If you are going to drink it, you should boil it first.
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Old 02-06-2011, 12:51 AM
brocks brocks is offline
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Google "acid rain."
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Old 02-06-2011, 01:21 AM
friedo friedo is online now
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Originally Posted by brocks View Post
Google "acid rain."
Acid rain is pretty unusual these days (unless you live in or near China), and in any case it's pretty harmless to drink in small quantities. The worst acid rain has a pH of about 2.5 -- which is about the same as a Coke.

It might not taste very good, though.
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Old 02-06-2011, 03:34 AM
LouisB LouisB is offline
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In the small Texas town where I grew up, nearly everyone had a "rain barrel" under the downspout of their gutter system. Women used rain water for their house plants and for washing their hair. Other than that, I don't remember any specific use; when the barrel was full, it was tipped over and emptied. I don't recall anyone ever using it as drinking water.
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Old 02-06-2011, 05:21 AM
penultima thule penultima thule is offline
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Originally Posted by madmonk28 View Post
I am by no means an expert, but I've worked on water sanitation projects in the developing world and it is usually recomended that rain water be used for irrigation and washing, not drinking. If you are going to drink it, you should boil it first.
I find this "rainwater is a life threat" notion a bit unlikely.

I can't see what bio-hazard there is going to be in freshly collected rainwater that necessitates boiling (presuming the container itself is not the source of contamination). The water gets into the atmosphere via evapouration, which is effectively boiling. What algae, protozoa, bacteria is going to contaminate the water up in the clouds?

Coming from the Australian bush, usually you had the option of the rainwater collected of the homestead and maybe one of bore, channel or river water.
Rain water collected of a galvanised iron roof, collected in a concrete tank, or a concrete lined corrogated iron tank, or more recently a plastic tank. Good water, and never needed to be boiled. You drank rainwater and possibly washed clothes in it, using the other (usually muddy or high in minerals) for the garden, toilet and other general puposes.

We'd use rainwater collected in glazed earthenware as distilled water to top up car/tractor batteries.
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Old 02-06-2011, 06:11 AM
psychonaut psychonaut is offline
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Originally Posted by penultima thule View Post
I can't see what bio-hazard there is going to be in freshly collected rainwater that necessitates boiling (presuming the container itself is not the source of contamination). The water gets into the atmosphere via evapouration, which is effectively boiling. What algae, protozoa, bacteria is going to contaminate the water up in the clouds?
Lots. The atmosphere is full of organisms, including bacteria, pollen, algae, fungi, insects, and viruses. There's an entire branch of biology devoted to its study. Some of the atmospheric biota is involved in the transmission of human disease, including through airborne water.
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Old 02-06-2011, 06:17 AM
Wallenstein Wallenstein is offline
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I think it's also the "freshly-collected" bit that causes problems.

As soon as the water sits in one place for a length of time it'll start to go stangnant, and could grow all sorts of algae etc.
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Old 02-06-2011, 07:08 AM
penultima thule penultima thule is offline
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Lots. The atmosphere is full of organisms, including bacteria, pollen, algae, fungi, insects, and viruses.
Yes, and we breathe that "cocktail" all the time generally without ill effect, not withstanding instances of hypersensitivity, hayfever and asthmatics etc.

I'm disputing the need to boil rainwater, presuming the container doesn't introduce contamination. It's not some developing world issue. I reckon there'd be a large slab of the North American farm sector who live on it, without the need to routinely boil it. That applies on this side of the puddle. Appropriately stored, It would be better quality than any supply sourced from surface water, be that river or lake.

And if water sits in a puddle on the ground, or a container long enough to become stagnant, that's not rainwater, and the nutrients and algae more likely to have been introduced since it fell.

At home our main water supply was a 250kl (66,000 US gallons) tank. Keep the leaves, dust and wildlife out of it and it supplied potable water for over 40 years. Nothing unusual from our perspective.
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Old 02-06-2011, 10:10 AM
Dunkelheit Dunkelheit is online now
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Originally Posted by sweeteviljesus View Post
I would not expect fresh rainwater to have any biological impurities, but what about chemical impurities? Have decades worth of antipollution measures made that a moot point?

Thanks,
Rob
Depends on where it's falling, IMO. I wouldn't use urban rainwater directly for drinking as it's probably got a fair amount of pollution in it, from falling through all the dust and combustion products and "NOx, SOx and VOCs" that are in the air from automobile exhaust, industrial emissions, wood/coal smoke, evaporation of volatile substances, and other sources. Antipollution measures have helped reduce, but have not eliminated such things, particularly in urban areas. One thing there is definitely much less of in the atmosphere now is lead, due to the replacement of leaded gasoline with unleaded, but once upon a time not that long ago, it would be a real concern for drinking and even gardening with urban rainwater. That said, water collected from the sky is still a lot cleaner than that which is running off of ground-level surfaces such as roads and pavements, or sitting in/on the ground having various pollutants dumped into it.

It also depends on how you're collecting it, what type of surface it's running off of, and what might have been deposited on said surface since the last rain. Many rainwater collection systems include a "first water" or "foul flush" disposal stage that either filters, rejects or withholds the first bucketful or so to avoid collecting the chemical-laden dust, bird waste, insects, and other pollution that has been deposited on whatever surface it's running off of (roof, etc). This water can be diverted to use as lawn irrigation or other purposes where the water doesn't have to be so clean as for washing and drinking.

Then too, there can be a brick or bag of some mineral substance (limestone, shell, marble chips, etc) to make the water alkaline in the the reservoir, that helps to prevent certain kinds of chemical impurities (acids, salts, heavy metals, etc) by adsorption or neutralisation or precipitation or whatnot. Rainwater is slightly acid to begin with from the carbon dioxide, nitrogen, etc in the air and my Permaculture Design Manual says that "washing and shower water can be soft (acid) but the water we drink is best made alkaline for the sake of health."

Indeed, washing water works best if it is soft, which is why rainwater has been used for so long for washing clothing and hair -- it helps to rinse out the alkaline soap residue, which was what made clothes dingy and hair heavy and flat before the advent of commercial detergents and shampoos. So it's probably best to have separate rainwater storage tanks for washing and drinking water, so that each has the best properties for the purpose. The collection surface can be the same, just leave the alkalinizing material out of the wash-water tank.

A couple of good diagrams included here:
Wateraid International Sustainable Technologies

A good look at rainwater collection:
Permaculture water harvesting write-up

Another page with extensive information, photos, diagrams, and references:
http://www.appropedia.org/Original:Rainwater_harvesting

My Permaculture Design Manual also has a couple of good diagrams that show some collection and storage systems that can be built at home, but I haven't been able to find them online yet.
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  #11  
Old 02-06-2011, 11:24 AM
Chronos Chronos is offline
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Acid rain is pretty unusual these days (unless you live in or near China), and in any case it's pretty harmless to drink in small quantities. The worst acid rain has a pH of about 2.5 -- which is about the same as a Coke.
pH doesn't tell the whole story, though, and almost all acids that strong will cause chemical burns. Coke specifically won't, but it's the exception, not the rule, and I certainly wouldn't want to drink a pH 2.5 aqueous solution of sulfuric acid (which is pretty much what acid rain is). That said, though, acid rain is, as you say, awfully rare in the western world nowadays.
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  #12  
Old 02-06-2011, 01:12 PM
Harmonious Discord Harmonious Discord is offline
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You can drink rain water safely. Collect it without contaminating it. Have you heard of a kid dying from eating snow or the people that melt it for drinking and cooking?
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  #13  
Old 02-06-2011, 01:51 PM
aceplace57 aceplace57 is offline
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My grandparent had a wooden cistern to collect water. They drank it for over thirty years. It stood beside the house. Their well water had too much iron to use for anything except laundry and showers.

Today, people use plastic cisterns.

Last edited by aceplace57; 02-06-2011 at 01:54 PM..
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  #14  
Old 02-06-2011, 03:27 PM
LouisB LouisB is offline
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On further reflection, when I first lived in Florida back in the 1960s there were still many houses with above ground cisterns; the easily accessible ground water smelled and tasted like rotten eggs. Those above ground cisterns relied entirely on rainwater and that water was used for everything in daily life, including cooking and eating. Way back then, water from springs, creeks and rivers could be used for cooking and drinking (drinking it was chancy) but that sure as hell ain't safe now.
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Old 02-06-2011, 06:34 PM
Leo Bloom Leo Bloom is offline
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Old 02-06-2011, 07:33 PM
Johanna Johanna is offline
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Malaysia's largest mosque, the Blue Mosque in Shah Alam, has a gargantuan dome made of aluminum covered with vitreous tile. It was built with channels to collect rainwater into storage tanks. The rainwater collected off the dome is used not for drinking, but for ablutions (which includes gargling, however). It's actually very ecological, since Muslims use vast amounts of water, and this would reduce the demand on the city's water supply considerably.
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Old 02-07-2011, 01:16 AM
Hennessy Hennessy is offline
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Plenty of other animal life survive off rain-water, correct? Surely (becky?) were not the exception.
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Old 02-07-2011, 02:16 AM
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I just wanted to re-emphasize Jeneva's point about flushing the "first water". Rainwater itself may be clean where you live, but if your locale has wet and dry seasons like most places, it can be several weeks or even months between rains. During that time, a lot of stuff can collect on your roof (or whatever collector surface you use) -- air pollution, animal and plant matter, bacteria, chemicals leeching out from the roof itself, etc. You don't want to drink that.

Whether the rainwater is drinkable depends on factors that vary from place to place and maybe even from month to month. And really, this is the same reason you use water filters when you go camping: 90% of the time you'll be fine without it, but 5% of the time you might get a bad stomachache and then 0.1% of the time you may end up somewhat dead. Is it worth it to you? Only you can answer that. If you want to be safe(r), boil the water, get it tested on a regular basis, install a filtration system, or do all the above. Appropedia also lists a few lower-cost or lower-tech water filtration methods that you can use in conjunction with the rainwater catchment, or if your area is hot enough, there's also solar distillation.

@ Jeneva: It's neat that you've heard of Appropedia (or did it just come up on Google?). I work with one of the guys who started it... neat to see it getting mentioned here

Quote:
Originally Posted by Hennessy
Plenty of other animal life survive off rain-water, correct? Surely (becky?) were not the exception.
Maybe this is a whoosh, but plenty of animal life survives off things that would kill us. Clean North American rainwater probably wouldn't kill us, but contaminated water in general can certainly cause anything between mild discomfort to mass deaths in less-developed nations.

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Originally Posted by Johanna
It's actually very ecological, since Muslims use vast amounts of water, and this would reduce the demand on the city's water supply considerably.
How do Muslims use more water than any other religion?
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Old 02-07-2011, 06:50 AM
Johanna Johanna is offline
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How do Muslims use more water than any other religion?
They have to pray five times a day, and before they can pray they have to splash water on their faces, arms, feet. After sex they have to have a whole body bath before praying. Any time going to the bathroom involves cleanup with water too. Islam is just a watery lifestyle.
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Old 02-07-2011, 07:40 AM
psychonaut psychonaut is offline
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They have to pray five times a day, and before they can pray they have to splash water on their faces, arms, feet. After sex they have to have a whole body bath before praying. Any time going to the bathroom involves cleanup with water too. Islam is just a watery lifestyle.
Judaism (and, to a lesser extent, Christianity) are also rife with superstitious ablutions. As with Islam, however, the degree of compliance varies from sect to sect and individual to individual.
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Old 02-07-2011, 08:03 AM
Turek Turek is offline
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Plenty of other animal life survive off rain-water, correct? Surely (becky?) were not the exception.
And vultures can eat rotten meat. But, personally, I'll pass.
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Old 02-07-2011, 08:22 AM
Dunkelheit Dunkelheit is online now
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I love the idea of solar stills. I would include a large sheet of transparent plastic in any survival kit I made up, mainly for that purpose. You can collect clean water just by digging a pit, putting fresh non-poisonous greenery in it and covering it with clear plastic, with a small rock or something in the middle to form a point for the condensation to run off into a container. Include a long tube that can sit in the container and emerge from under the plastic, and you don't even need to dismantle it to drink the water. ;-)

Quote:
@ Jeneva: It's neat that you've heard of Appropedia (or did it just come up on Google?). I work with one of the guys who started it... neat to see it getting mentioned here
I had actually never heard of it until I was Googling for good examples. It seems like a great project, I'll definitely give it a closer look. I'm always keen to find good resources for this sort of thing, bit of a passion of mine really.

Quote:
Maybe this is a whoosh, but plenty of animal life survives off things that would kill us. Clean North American rainwater probably wouldn't kill us, but contaminated water in general can certainly cause anything between mild discomfort to mass deaths in less-developed nations.
Yes, it seems that a lot of other animals, especially those which are commonly carrion-eaters, can tolerate a broader range and higher volume of biological contaminants than we can. Whether they're any less susceptible than us to chemical contamination, well, I wouldn't bet the farm on that one. Some, like amphibians, are noticeably more sensitive than us to certain chemicals. And we don't really have any records on the number of wild animals regularly killed or sickened by contaminated water, do we?

Last edited by Dunkelheit; 02-07-2011 at 08:23 AM..
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Old 02-07-2011, 09:27 AM
robby robby is offline
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Acid rain is pretty unusual these days (unless you live in or near China), and in any case it's pretty harmless to drink in small quantities. The worst acid rain has a pH of about 2.5 -- which is about the same as a Coke.

It might not taste very good, though.
The most acidic rain measured in the U.S. has a pH of about 4.3, with more typical values for acid rain ranging between 4.5 and 5.0. This acidity comes from sulfuric acid and nitric acid that result from sulfur dioxide and nitrogen oxides present in the emissions from power plants, vehicles, and factories.

Note that while pure water has a pH of 7.0, even clean, uncontaminated rainwater has a pH of approximately 5.6. This is because of the presence of CO2 in the atmosphere (which dissolves in rain to produce a weak solution of carbonic acid).

Note that a solution with a pH of 2.5 is 100 times more acidic than a solution with a pH of 4.5. While classic Coca Cola does have a pH of about 2.5, it is much more acidic than typical acid rain. Typical acid rain has an acidity somewhere between orange juice and black coffee.

That being said, acid rain does cause enormous damage to ecosystems. It's not that unusual, either, but the Clean Air Act and other environmental regulations has helped in this respect, and it's certainly not as bad as used to be.

Cite. Another cite.

To address the OP, rainwater is perfectly safe to drink. I might prefer not to drink rainwater immediately downwind of an industrial smokestack, though, out of an abundance of caution, but even then it would likely not be harmful.
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Old 02-07-2011, 09:35 AM
Bam Boo Gut Bam Boo Gut is offline
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We catch it off the roof here in the West Indies and drink it after storing it in plastic tanks or underground cisterns. People usually have a filter on their cistern water and obviously cisterns need to be drained and cleaned from time to time as do the tanks.
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Old 02-07-2011, 12:48 PM
purplehorseshoe purplehorseshoe is offline
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We had no water over the weekend (burst pipes) and collected freshly-fallen snow to melt for flushing the toilets. The snow was pristine-looking: artic white, fluffy, gorgeous.

The water that melted from it once we microwaved it? Yuck. It was reddish. Definitely not for drinking without further purification. (Fine to poop and pee in, though.) I'm in an urban area - YMMV if you're away from civilization and attendant pollution.

Last edited by purplehorseshoe; 02-07-2011 at 12:49 PM.. Reason: clarified geography
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Old 02-07-2011, 01:17 PM
robby robby is offline
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...To address the OP, rainwater is perfectly safe to drink. I might prefer not to drink rainwater immediately downwind of an industrial smokestack, though, out of an abundance of caution, but even then it would likely not be harmful.
I should clarify that precipitation collected directly in a clean container is safe.

Rainwater running over the ground or a roof first may not be safe to drink. Snow may not be, either, depending on how long it's been on the ground.

Last edited by robby; 02-07-2011 at 01:18 PM..
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Old 02-07-2011, 01:22 PM
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They have to pray five times a day, and before they can pray they have to splash water on their faces, arms, feet. After sex they have to have a whole body bath before praying. Any time going to the bathroom involves cleanup with water too. Islam is just a watery lifestyle.
Is this really a significant amount of water? Splashing aside, don't most people use water after going to the bathroom and take baths after sex?

"Islam is just a watery lifestyle" -- that's just hilarious
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Old 02-07-2011, 10:45 PM
Johanna Johanna is offline
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Technically, you could do the entire ablution with just half a pint of water. You're actually supposed to use water sparingly like that. But the average modern Muslim is likely to leave the tap running the whole while and easily blow a gallon per person each time.
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Old 02-08-2011, 01:06 AM
Hennessy Hennessy is offline
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Good thing this question has nothing to do with rotten meat, I wouldn't know how to answer... Food is food and water is water which btw, we need to live. I'm sure if it came down to it my survival instincts would look around for a needle and pop my air tight bubble and then it would knock me to the ground and drag me to the closest puddle and force me to drink it while I'm "trying" to scream for help. I should be thankful though because I just lived a little longer thanks to that dreadful rainwater. But there is always a catch, live now die later. Wait a minute, that's the catch for everything I do. You almost had me convinced vulture watcher, I was about to quit hunting with Dick Chaney.
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Old 02-08-2011, 01:12 AM
Chronos Chronos is offline
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Quoth Jeneva:
Quote:
And we don't really have any records on the number of wild animals regularly killed or sickened by contaminated water, do we?
This is something that I've brought up before, too: If there's something that kills, say, 5% of the population of some wild animal, the population is probably going to be able to keep up with it, and it won't really have a big effect on the numbers in the long run. But if something kills 5% of the humans that are involved with it, we'd consider that a huge tragedy, and be militant about taking steps against it. By the standards of survival of the species, it's still not all that big a deal, but we tend not to think of human lives in just those terms.
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Old 02-08-2011, 01:28 AM
fifty-six fifty-six is offline
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Rainwater is awesome. I prefer it to tap. I don't have to haul it and it possably has less chemicals in it than tap.
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Old 02-08-2011, 01:49 AM
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Good thing this question has nothing to do with rotten meat, I wouldn't know how to answer... Food is food and water is water which btw, we need to live. I'm sure if it came down to it my survival instincts would look around for a needle and pop my air tight bubble and then it would knock me to the ground and drag me to the closest puddle and force me to drink it while I'm "trying" to scream for help. I should be thankful though because I just lived a little longer thanks to that dreadful rainwater. But there is always a catch, live now die later. Wait a minute, that's the catch for everything I do. You almost had me convinced vulture watcher, I was about to quit hunting with Dick Chaney.
I gotta ask... have you been drinking much rainwater lately?
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Old 02-08-2011, 08:49 AM
Dunkelheit Dunkelheit is online now
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This is something that I've brought up before, too: If there's something that kills, say, 5% of the population of some wild animal, the population is probably going to be able to keep up with it, and it won't really have a big effect on the numbers in the long run. But if something kills 5% of the humans that are involved with it, we'd consider that a huge tragedy, and be militant about taking steps against it. By the standards of survival of the species, it's still not all that big a deal, but we tend not to think of human lives in just those terms.
Well, quite.

Last edited by Dunkelheit; 02-08-2011 at 08:51 AM..
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Old 02-08-2011, 09:49 AM
Polycarp Polycarp is offline
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Acid rain is pretty unusual these days (unless you live in or near China), and in any case it's pretty harmless to drink in small quantities. The worst acid rain has a pH of about 2.5 -- which is about the same as a Coke.

It might not taste very good, though.
I need to jump in on this one. Take a look at a map of New York State that shows the counties. Then look east of Lake Ontario. You'll see an area where Oswego and Lewis Counties have a common border. Make a sinuously-straight line hugging the northern half of that border in a roughly north-south alignment along the east, Lewis County side. That is a stream called Prince Brook, part of the Salmon River watershed. This is in the area of the U.S. which gets the highest snowfall east of the Rockies.

The reason I single out Prince Brook is that it is fed largely by snowmelt, being a rather unimpressive trickle during late summer and fall, though with heavy flows in the spring. And during the height of the concern over acid rain, before air pollution retrofits were demanded on Midwestern factories, power plants, etc., Prince Brook had a spring-runoff pH of 1. That's equivalent to table vinegar. Granted, this is an extreme -- that's why I picked up on it, because it was an extreme, to illustrate how bad acid precipitation could get.

Last edited by Polycarp; 02-08-2011 at 09:50 AM..
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Old 02-08-2011, 02:47 PM
Chronos Chronos is offline
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A pH of 1 is far stronger than table vinegar. In fact, Coke is significantly stronger than vinegar. The only things you'll find in your kitchen with a lower pH than Coke are cleaning supplies.
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  #36  
Old 02-08-2011, 05:14 PM
ZenBeam ZenBeam is offline
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Polycarp, can you find a cite for the pH of 1? I'd believe that if it was due to some kind of mining leftovers, but for snowmelt, I'm just not seeing it.
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  #37  
Old 06-26-2011, 05:04 AM
shijinn shijinn is offline
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what if you live in Japan?
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Old 06-26-2011, 05:48 AM
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A pre-school somewhere in Auckland a couple of years ago wanted to install rain-water collection tanks for the school's use, but where forbidden to do so, IIRC. I heard this at a local community board meeting, when experts were reporting about zinc contamination in our local streams -- from unpainted and unsealed galvanised iron roofs. Aside from bird droppings and the like, zinc (if using a galvanised iron roof as the collection source) might be the only other major concern about rainwater.

Out in rural areas here and the off-shore islands, rainwater is a necessity where there's no reticulation. Haven't heard of any community dying in droves due to using it.
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Old 06-26-2011, 06:25 AM
kanicbird kanicbird is offline
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In Hatti rainwater is usually collected off gutter systems to use as household potable water including drinking.

In wilderness situations rain water is usually considered safer then some water sources such as lakes. IMHO taste wise rain water is a bit lacking over ground water or a flowing stream source.
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Old 06-26-2011, 10:13 AM
coremelt coremelt is offline
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I own some land in Tasmania in Australia. So far I have no road, power, water or house, it's just land. But all my neighbours have water tanks that collect the rain water from the roof. An 80,000 litre tank is enough to last through the summer for all water, showers and everything and it's not that big.

So the answer is yes
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Old 06-27-2011, 04:34 AM
constanze constanze is offline
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Originally Posted by madmonk28 View Post
If you are going to drink it, you should boil it first.
I'm a bit surprised at this: I thought that with scarcity of heating fuel, and the tests done on plastic bottle UV sterilisation*, this method would be taught to people in 3rd world?

* They tested putting a clear plastic bottle, like the 1.5 l soda comes in, filling it with contaminated water (from an open slum river for example) and laying it in the sun for 4 hours, and the UV in the sun light had made it safe to drink.
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Old 06-27-2011, 06:04 AM
Polycarp Polycarp is offline
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Quote:
Originally Posted by ZenBeam View Post
Polycarp, can you find a cite for the pH of 1? I'd believe that if it was due to some kind of mining leftovers, but for snowmelt, I'm just not seeing it.
Well, I realize this response is only 4.5 months late, but here goes: The figure comes from field work conducted by a college environmental studies program in the mid-1970s. I don't at this late date recall whether it was Cornell, Syracuse U., or SUNY CESF. It was cited in a position paper on the effects of acid rain in the Tug Hill area prepared by the NYS Tug Hill Commission. That paper, unfortunately, seems to be no longer listed as publicly available, but there will be copies in at least those three schools' libraries and the state library. I'd hoped to chase down the datum for you back when you asked, but got sidetracked and apparently never answered. Not the greatest cite in the world, but the best I can do.
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Old 06-27-2011, 08:45 AM
Hari Seldon Hari Seldon is offline
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If I can breath it, I can drink it.
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Old 06-27-2011, 09:31 AM
madmonk28 madmonk28 is offline
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Quote:
Originally Posted by constanze View Post
I'm a bit surprised at this: I thought that with scarcity of heating fuel, and the tests done on plastic bottle UV sterilisation*, this method would be taught to people in 3rd world?

* They tested putting a clear plastic bottle, like the 1.5 l soda comes in, filling it with contaminated water (from an open slum river for example) and laying it in the sun for 4 hours, and the UV in the sun light had made it safe to drink.
In Indonesia, where I set up the water collection points, heating fuel scarcity wasn't an issue. Again, I'm not an expert, I was just the manager making sure the project got done. Our funder, UNICEF, required that we put signs up and conduct trainings for the community informing them that they should boil the collected rain water prior to drinking, this likely had to do with the fact that it would sit for long periods and collect debris, mosquito eggs, etc.
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