Storing Drinking-Water in Copper Pots Kills Contaminating Bacteria (2012) | Hacker News Reader

Storing Drinking-Water in Copper Pots Kills Contaminating Bacteria (2012)

ncbi.nlm.nih.gov

160 pointsRed_Tarsius136 comments

Using copper vessels to store water for drinking is somewhat common in parts of India. Seen it in Maharashtra.

Lead vessels were traditionally used (and may still be) to make certain dishes (like rasam, a watery lentil-based sour soup) in South India. No idea about any benefits or the reverse.

Update: Also, I've seen relatives of the previous generation to mine (in India), sometimes eating from silver plates. Not sure, but I think that may have been for some supposed health reason too (seeing sibling comment about silver reminded me of it).

Just as a PSA, lead in any quantity is toxic and particularly so for children. Copper, silver, and gold are in the same family of elements (group 11) and lead is in the carbon family. Very different characteristics.

edit: I should also note (since bringing up families of elements) that - supporting your anecdote - silver has known and studied antimicrobial properties (https://www.ncbi.nlm.nih.gov/pubmed/16766878). Sadly it has been coopted by quacks, so there's also a lot of misinformation out there about it, too.

Thanks for the info. Yes, I've read about leaded petrol and its effects on the brain, more so in children. I even read somewhere a while ago (maybe on HN) that crime had come down somewhat over some decades (in the US?), which was partly attributed (in the article I read) to reduced use of leaded petrol (gasoline).

Interesting about the silver study, and agree about quacks.

Worldwide probably...

http://www.motherjones.com/kevin-drum/2015/01/yep-gasoline-l...

Interestingly, the guy (Thomas Midgley) who thought to add lead to petrol is the same guy who thought of using CFCs for refrigerants.

Wow, what a tragic guy:

"J. R. McNeill, an environmental historian, opined that Midgley "had more impact on the atmosphere than any other single organism in Earth's history."

https://en.m.wikipedia.org/wiki/Thomas_Midgley_Jr.

No kidding about the silver being co-opted by quacks. If "colloidal silver" is taken in any decent quantities, it'll turn you a little blue. This is a libertarian guy who's attempted to run for a couple of different positions in the USA: http://news.bbc.co.uk/media/images/38297000/jpg/_38297733_bl...

I agree, quacks were already there and silver was just what some of them gravitated towards some of the time.

Turns out that non-ionic silver at concentrations of 10 to 30 ppm by weight in otherwise pure water of neutral pH will kill germs quite remarkably. Without the risk of argyria to any degree upon consuming at least a pint a day with regular sun exposure in addition.

As has been known for years, the depicted politician is suffering from consumption of an overdose of silver in general, likely orders of magnitude beyond the level needed for germkilling, and also likely to have been in ionic form. One big slug of poorly-crafted material created according to any number of questionable procedures could be enough to cause this type of permanent discoloration.

Probably not the kind of thing to try at home.

Although it is sometimes suspected that overdoses of ionic silver occurred often enough when cooking or serving acidic foods in sterling kitchenware over the centuries to royalty, that the term "bluebloods" was coined.

Also, there is some possibility the blueness used to represent some dieties in India gives a good idea of what a prototype royal figure might have looked like if too much silver was consumed intentionally or not.

OTOH, a true colloid crafted after decades of professional silver electrochemistry, of known concentration as measured by state-of-the-art laboratory techniques, can be considered almost like a completely different animal.

If I ever meet anyone with the guts to take it to clinical trials, I'll gladly supply the material.

All it takes is one physician single-handedly at the least, as long as nobody is in a hurry, it could be done in spare time like the process was invented, no deadlines. Simply the confidence to know you can accomplish what others do not dream of doing on their own.

> Copper, silver, and gold are in the same family of elements (group 11) and lead is in the carbon family.

By that, I'm guessing you mean in the periodic table. Been a while since I looked at that, should check it out again out of interest.

Yup, a lot of chemical properties are dictated by the number of outermost free ("valence") electrons, and atoms in columns in the periodic table all have the same number of valence electrons, hence similar chemical properties.

The University of Nottingham's School of Chemistry has some great, brief videos on various elements if you're ever interested: https://www.youtube.com/channel/UCtESv1e7ntJaLJYKIO1FoYw

Interesting, will check them, thanks.

Copper, silver, and gold are also toxic in high doses but not in the same extreme way as lead, which should be kept as close to zero as possible.

Gold... toxic?

there was even an episode of house where the cause was gold poisoning.

I'm pretty sure it was silver, not gold.

It gives a person a "gray/purple" skin color that makes them look dead. See: https://en.wikipedia.org/wiki/Argyria

That doesn't necessarily mean that the element is poisonous per se. Many good/healthy substances are poisonous at high levels,e.g.: Vitamin A poisoning [0] Water poisoning [1]

[0] https://en.m.wikipedia.org/wiki/Hypervitaminosis_A [1] https://en.m.wikipedia.org/wiki/Water_intoxication

Yes, empirically, I guess at least gold cannot be too or immediately toxic, since thin gold leaf is sometimes put on sweets as a decoration in India - usually on peda kind of sweets:

https://en.wikipedia.org/wiki/Peda

https://en.wikipedia.org/wiki/Vark

Silver too, according to the above page.

If I recall correctly, gold is extremely unreactive as far as metals go -- I'd imagine that it may just be more-or-less biochemically neutral.

Edit: I may be dead wrong. https://en.wikipedia.org/wiki/Organogold_chemistry

I think you're correct. Pure gold is extremely hard to dissolve or oxidize. There's three common methods, using a mercury amalgam(which is an alloying, so the gold is still unreacted), cyanide, or a mixture of hydrochloric and nitric acid called aqua regia.

According to https://en.wikipedia.org/wiki/Gold#Toxicity, the gold ion is toxic, but there are no chemical processes known to occur in the human body that can solubilize metallic gold.

> Yes, empirically, I guess at least gold cannot be too or immediately toxic

Gold goes out from the body unchanged from how it went in.

An attribute capitalized upon by this product http://incrediblethings.com/food/this-gold-pill-makes-you-po...

Fun fact - tomatos were actually considered poisonous in parts of europe for a long time, since they have high acidity and leach toxins from lead plates http://www.smithsonianmag.com/arts-culture/why-the-tomato-wa...

I find it hard to believe that the Europeans (Italians? English?) would have feared tomatoes because the acidity leached lead from pewter plates.

Several reasons:

1. Tomatoes have a high acidity, but many other foods (I mean, wine, for crying out loud! From ubiquitous pewter glasses!) would have had a higher acidity. Vinegar was commonly used in a variety of dishes.

2. Lead poisoning is not usually a sudden event that causes you to say "My god! Must have been the tomatoes!" If there even was a connection, it would have taken a large scale analysis that would have more strongly identified that "people who eat off of pewter tend to get these symptoms." After all, it wasn't just the wealthy eating tomatoes. It just makes no sense that they could have linked the two, especially after all of the incredibly blatant health hazards that hadn't been linked together.

3. Tomatoes are clearly a member of the nightshade family, and this was known in the 1700's. Although lots of great things come from the family (chili peppers, tobacco!) they're often not things to mess with, and might kill you. Potatoes also had a similarly bad reputation because of this. An over-cautious biologist and a little misinformation (or perhaps an early variety of tomato with too much solanine or something nasty in its leaves) seems a lot more likely than "lead poisoning"

4. The source that was linked to for this "fact" is a book on growing Heirloom tomatoes that has nothing to back this up at all, and is far from a "scholarly resource" Seems like a lot of irresponsible reporting.

Little known fact: lead might be one of the reasons of the decline of the Roman Empire, because they used it inside the pipes carrying water. https://en.wikipedia.org/wiki/Lead_poisoning#History

I would have thought that was a well known fact. It's brought up virtually every time lead toxicity comes up...

Cooking sour liquids in lead vessels makes them sweeter - but not in a way you want. The lead reacts with acetic acid to make lead acetate, "sugar of lead." The Romans used this method to sweeten sour wine. It's the oldest artificial sweetener, and the oldest dietary source of lead poisoning.

For rasam, it's tin, not lead.

But lead has sometimes traditionally been used in cooking etc, because many lead salts are sweet :( That's why children chew on flakes of leaded paint. They're like candy :(

>For rasam, it's tin, not lead.

Could be, I was going by what I've heard from elders. They could have been wrong.

I hope that they were wrong. Tin looks a lot like lead. It's harder, but melts at a lower temperature. I doubt that one could coat cookware with pure lead, because it oxidizes too quickly, but alloys (e.g. solder) might be used.

It is indeed tin, despite the name you heard (eeya-chatti, or eeya-pathiram I'm sure) from your elders.

The Tamil word Eeyam has two overloaded meanings, one is tin/pewter, the other is lead.

Unfortunately, "Eeyam" is almost always translated into "Lead".

I think you're right, thanks.

Varg Vikernes (author of Burzum) mentioned that European barbarians used to clean water by letting it stand in a copper vessel over night. The custom of throwing coins into sources or wells might come from this pagan tradition.

Interesting ...

Never thought I would see Burzum mentioned on here, that's hilarious. Did a double take when I saw the name

Silver has some antimicrobial properties, as well as several other metals.

I will just leave it here in case someone will want to employ copper pots: https://www.ncbi.nlm.nih.gov/pubmed/10383875

Interesting. Two studies with pretty much conflicting conclusions about safety of copper for potable water. I imagine that there is a level (range) of exposure that is in the sweet spot between 'kills harmful microbes' and 'kills/harms humans who drink the water'.

One study is abut storing water in copper pots and the other is about copper in drinking water. Does storing water in pots automatically mean that the copper goes into the water and if yes, how high is the concentration?

TFA looked at the copper concentration in the water after storage and it was below WHO guidelines for safe copper levels. Whether the WHO guidelines are sufficient or not is another question.

The WHO guideline for copper is 2mg/l which is the same as in the German guidelines "Trinkwasserverordnung". The article linked by batter says right in the abstract:

We found that the disease can even be caused by copper concentrations below the allowed concentration given by the German Guidelines for Drinking Water (Trinkwasserverordnung).

>Does storing water in pots mean that Cu goes into water

It's not automatic, but depends on pH. Acidic conditions will be favorable to metals leaching into water. The paper cites an initial pH of 7.84, and final pH of 7.94 - so the pH increased slightly as a result of the copper entering the solution.

This pH change correlated with 177 ppb Cu concentration in these pots after 16 hours. If initial pH was lower this concentration would see a logarithmic increase in relation the lower initial pH over the same time interval.

"Since distilled water is slightly acidic (pH 6.7±0.05) which might enhance copper leaching, we have demonstrated the effect of copper pot in regular drinking-water"

A quick google says: Drinking water in the US of A must have at least a pH of 6.5. They should have tested with that.

I assume, the copper concentration would increase over 10-fold in that case versus the tested case.

How is storing it in copper pots significantly different than "storing" it in the copper pipes prevalent in a majority of houses in the USA?

That's true for houses of a particular age and value. New stuff is all PEX, and has been for some time. Old enough houses would have been cast iron. Cheaper houses (mobile homes, for example) were all PVC for a long time.

I had to dig up and repair a sewer pipe yesterday, and was somewhat surprised to find that it was made of clay tile.

in Los Angeles county (and, I believe, LA City), clay pipe is still an approved material for sewer pipe laterals

http://dpw.lacounty.gov/general/faq/index.cfm?Action=getAnsw...

http://library.amlegal.com/nxt/gateway.dll/California/lamc/m....

'icantdrive55 the thread is about water supply lines, not boilers or HVAC evaporator coils. I've dealt with a number of plumbers over the last several years, and not one wanted to use anything but PEX for supply lines. Actually a different preference would be a strike against any plumber I'd consider hiring for new work. Also you appear to be hellbanned.

That's a pretty wacky position.

The only meaningful strike against copper is commodity cost.

Of course they wanted to use PEX. It's cheaper and easier for them to install, since they don't have to solder anything. But there are definitely some concerns about PEX. http://www.calpipes.org/ProtectingCalifornians_PEX.asp It leaches a lot of chemicals which may or may not be harmful, but which certainly do cause an odor. It is permeable to some pesticides, oil, gasoline, and benzene. It is not anti-microbial like copper is, which means you get biofilms. If it's exposed to sunlight for two weeks (perhaps because some contractor left it outside), its chlorine resistance disappears. It is not recyclable, and makes toxic smoke when it burns. But it is 1/3 the cost. Your choice.

Eh, what is the expected lifetime of PEX tubes?

The building code in USA is a bit relaxed compared to northern Europe, but can you have PEX tubes inside walls?

I think the recommendation here is a dual tube system, with a PEX pipe inside a protective outer tube.

I think the typical warranty is 25 years? With all the lawsuits the EIFS people faced, one would expect most manufacturers to be very sure about this sort of thing...

Yes, you can have PEX enclosed in finished walls in most US cities. Only need to sheath when subject to damage (e.g. Passing through potentially abrasive material)

Our main sewer line is Orangeburg. I look forward to replacing it soon.

New stuff is not all PEX. Some people prefer copper because of its anti-microbial properties and because it's a known quantity that has been used for a very long time. PEX was only even approved in California in 2009, and there was a lawsuit about the stuff it was leaching into the water. Whether it's safe is controversial. Whether it's stinky is not-- PEX causes the water to smell bad. https://www.purdue.edu/newsroom/releases/2014/Q4/drinking-wa...

Also, nobody cares what sewer pipes are made of. Cast iron is a popular choice, but it could be just about anything, since you're not drinking the water (one hopes.) In California, they even used to make them out of pressed wood pulp and pitch in the 1960s... another wonder material that turned out to be not so wonderful in the long term... https://en.wikipedia.org/wiki/Orangeburg_pipe

I guess it was still better than cement-asbestos pipe, though. Which is still used to supply tap water in some cities. :( Another wonder material of a bygone era.

Good point, probably similar I imagine

I suspect that outcome depends on water pH and temperature. One doesn't use copper pots for cooking acidic tomato sauce, for example. Acidic well water corrodes copper plumbing.

Not surprising, there is no contradiction. Copper is toxic to many forms of life.

I somehow got copper in my fish tank...

Don't.

Lots of fish medication is copper based due to antibacterial/anti-parasitic action.

Real bad for invertebrates though.

In retrospect, the dead snails should have been a sign. I got a lot more copper in the water than fish could survive.

Fortunately there were no fish in it yet.

"Copper content (177±16 ppb) in water stored in copper pots was well within the permissible limits of the World Health Organization. Copper holds promise as a point-of-use solution for microbial purification of drinking-water, especially in developing countries."

Yeah but they didn't test waters of different ph levels. I'm not sure if that would be an issue though.

It could be an exponential curve and also be influenced by other ions in the water.

Safety standards aren't as black-and-white as the law. Some people will suffer way earlier than other people. Some people can tolerate some substances in way higher concentrations than the average person.

Just remember the authors are suggesting copper pots for water storage in developing countries, where people have more chance of dying from diarrhea than from prolonged exposure to copper.

My water is delivered in copper tubes... It can't be that bad, can it?

It probably spends most of it's time in cast iron though and only the last hundred or so feet in copper... I'm in the same boat though

There is more information here: http://www.health.state.mn.us/divs/eh/water/factsheet/com/co...

If you have old copper pipes you're probably fine. An oxide coating builds up on the pipes over time that prevents the release of copper.

If you have a water filter you're probably fine (although check the particular filter to see what it removes.) You should have a water filter anyway if you live in any area that used to have industrial sites.

Copper intake needs to be balanced out by zinc intake since they are antagonists regarding resorption in the intestines (This article says 1 copper to 15 zinc: http://www.livestrong.com/article/336425-side-effects-of-tra...), so if you supplement a lot of zinc you might be fine using such a pot.

I store filtered drinking water in various plastic containers (often used juice bottles or the bottles that I boght store-bought water in). I wonder how health effects from the chemicals leeching in to my water from these plastic containers compare with the health effects from using copper containers, or perhaps ceramic/porcelain containers as those are supposed to be non-reactive.

I do that too, sometimes, particularly when on trips in rural / forest areas / resorts (refill the plastic bottle at the camp place or resort's restaurant with filtered water from a water purifier) but as a heuristic, to mitigate any possible effects of the plastic chemicals, I throw away the bottle after a week or two.

Doesn't that do the opposite of what you intend? I imagine plastic stuff obviously leaching at a decaying rate.

Interesting point, hadn't thought of it in that way. My "logic" was (though not thought through rigorously) something like this, maybe: the plastic may decay more with time and with handling and exposure to sunlight, hence throw the bottle after a week.

drop me a line at gmail, if you have the time.

Copper pots are used for cooking because of the superior heat transfer, but you are not cooking with copper directly. They are "tinned", and this coating needs upkeep. You can't really cook with it directly because it's too reactive with acidic foods.

Modern ones are coated with stainless steel which needs no maintenance

true, modern ones are electroplated - can still be called tinning in practice although that's inaccurate. It doesn't need anything like the same maintenace as old style.

The point was more that nobody really cooks directly with copper, and did not historically.

Silver is also known to have antibacterial/antimicrobial properties and is used both as a coating on handles, surfaces to prevent bacterial buildup and also in typical creams as an antibacterial option (however, I do believe a recent study showed it to be no better than a control when applied topically to burns, which is/was one of its primary uses).

Both copper and silver oxidize unpleasantly very quickly, though.

These clinicians do a nice summary of what they think the evidence is: http://www.woundsinternational.com/media/issues/567/files/co...

That's an old document, and I'd be interested if there's anything newer.

Silver sulfadiazine 1% cream is a highly effective antibiotic for preventing infections in deep burns.

In my experience, while while the wound is open, this was the only cream that had no skin reactions, and that made it far easier keep it on 24/7. The cream kept air out, greatly reduced pain. Eliminating infection allowed more rapid healing.

I don't know whether it's prescribed today, but it was the only cream that was effective at both reducing pain, and speeding healing.

Yup, it is still prescribed. They gave it to me after I had surgery on ingrown toenails on both sides of both big toes [1]. My Podiatrist used acid to burn away part of the nail matrix to prevent the outer quarter of each toenail from growing, reducing my toenail to half width. That prevented the problem from happening again [2]. Silvadine kept my toes from getting infected further and they healed rather painlessly. All in all good medicine.

[1] Genetics and apparently bad grooming habits for the win! [2] A smashing success for ten years and counting. About 1/8 of each side grew back but it's not physically possible for me to get ingrown toenails unless I intentionally try to induce them.

Yes, that's all I've ever heard. However: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002106...

http://www.burnsjournal.com/article/S0305-4179(16)30056-0/fu...

Wow, thanks for the references. My experience was 10 and 15 years ago, and the newer dressings sound great.

Conclusions the first link: "silver sulphadiazine (SSD) was consistently associated with poorer healing outcomes than biosynthetic (skin substitute) dressings, silver-containing dressings and silicon-coated dressings".

Results in the second link: "Many dressings showed superior healing properties compared to SSD, but no dressing was able to show a clear benefit over SSD regarding infection. The number of dressing changes, pain and patient's satisfaction are more favourable in the newer dressings, especially with solid and biological dressings."

These were certainly the critical factors for me -- reducing pain made it easier to keep applied. Reducing number of changes is icing on the cake.

For deep burns, debriding the wound is an extremely painful process. If the biosynthetic or silica materials reduce that, it'd be a huge advantage.

"We had also reported the benefit of using a copper-based device, contrived by us, which was as effective as the pot but at a fraction of the cost." [12]

[12] https://www.ncbi.nlm.nih.gov/pubmed/19230946/

(Device spoiler: Water in glass bottles with copper coils.)

I have a copper water bottle that I bought online from India:

https://i.imgur.com/3k2QBQI.jpg

I love the thing, and I was drinking water out of it...

But one time I put alcohol in it... and I took a few sips from it and I almost immediately started feeling nauseous and weird... now I'm scared to use it, even for water.

That doesn't sound normal. Many alcohol stills use copper (wikipedia has this bit of information: "(a copper still) removes sulfur-based compounds from the alcohol that would make it unpleasant to drink")

Yeah, that's why I'm scared of it now... any clue how I could test it?

What are the sides sealed with? Alcohol is a good solvent so it may be an adhesive flavor youve tasted.

You could check the density if you think its not actually copper material though.

There are copper testing kits for aquarium water, but your health isn't really worth risking with a $10 aquarium test. Throw it away and buy a new one, and research how to properly handle copper cookware.

A Moscow Mule is typically served in a copper mug, and I'd think the negative effects from the alcohol would be the primary thing to worry about.

The thing to worry about would be poisoning from copper toxicity (by misuse above, or by overuse of copper sulfate), or if made with beryllium, beryllium poisoning. If somehow 30mg/kg of copper were swallowed, it is potentially lethal. And if any food residue is left stuck to a piece of copper cookware, it should be thrown out immediately so it doesn't leech copper out.

If all he ever did was serve a cold moscow mule using his "copper water bottle", maybe the alcohol is the problem. But we only know he used it to drink water and alcohol. We don't know if it's lined, or if the lining was damaged, or if he used a hot or acidic liquid inside it at some point, or whether it has a corrosive residue.

only water, and once bourbon.

Most current commercial mugs have a lining in them to prevent any leaching but still allows you to maintain the look and also the copper to help with temperature.

I can't find a quick reference but I read a while back that the drink, possibly the acid from the juice, reacted with the copper to add a flavour to the drink. With the lined mugs you don't get that specific taste.

The antibacterial properties of copper are well known, and were proven long ago. I think this is just someone looking for something to research and write a paper on.

> and were proven long ago.

Can you back up your claim?

First discovered in 1893. https://en.m.wikipedia.org/wiki/Oligodynamic_effect

There are a whole class of heavy metals that act as germicides.

Silver is used (in a cream) to prevent infection in wounds, particularly burns.

I've been making a deodorant created from connecting a few 9v batteries to two copper electrodes in distilled water, followed by the same with two silver electrodes, then blending the results with a bit of alcohol and essential oils. I put it in a spray-bottle and hit the pits with it. Seems significantly more effective than the essential oils alone or conventional products.

For discovery.. (though not 'scientific').. Try 1500-2000 BC

https://www.copper.org/publications/newsletters/innovations/...

Not sure about copper pots specifically, but Wikipedia has a reference suggesting 1893 [0].

[0] https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co...

and while at the time probably based more on observation than a proven mechanism https://en.wikipedia.org/wiki/Copper_sheathing dates to 1700's

And the wiki article has another reference [0] stating, "The first recorded medical use of copper is found in the Smith Papyrus, one of the oldest books known. The Papyrus is an Egyptian medical text, written between 2600 and 2200 B.C., which records the use of copper to sterilize chest wounds and to sterilize drinking water."

[0] https://www.copper.org/publications/newsletters/innovations/...

From [0]

Interestingly, silver may be ineffective against MRSA, while copper is fatal.

Thanks. Should have googled.

However, upon closer inspection, it seems like there was a wave of research during 1960s which looked at Copper ion concentration between 0.02 - 10g/L

In the 2000s there was another wave of research looking at antimicrobial properties, however sampling a few of them, it does seem like they were seen as growing surfaces rather than containers for water purification.

So, I guess it was observed for a long time, scientifically studied fairly recently, and not in particular whether it was viable in a practical setting?

> it does seem like they were seen as growing surfaces rather than containers for water purification.

> So, I guess it was observed for a long time, scientifically studied fairly recently, and not in particular whether it was viable in a practical setting?

It's pretty likely that no one really looked into the antimicrobial properties of copper surfaces until the advent of biofilm research (essentially Bill Costerton's paper(s) [0][1]). Without that idea, there wasn't a way to talk about or study what was happening, and there was no funding.

So, yeah, the better studies would've come out around ~2000.

I don't see a very practical use for suspensions of copper compounds as antimicrobials (maybe topical treatments only), but lots of uses for copper surfaces.

[0] http://www.nature.com/nrmicro/journal/v12/n11/full/nrmicro33...

[1] http://jb.asm.org/content/194/24/6706.full

Wikipedia would be a good starting point: https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co...

The problem with copper is, it's toxic to more or less everything. No, it isn't as bad as lead, and humans tolerate it far better than most organisms, but I'd still rather not ingest it.

The best treatment for wood exposed to the elements is copper-based. In USA, however, the requirements for treatment facilities have grown more and more onerous, so that it's fairly impossible to find such wood anymore.

About a month or two ago here in California, I picked up a bunch of pressure treated 2x4s from Home Depot. They're copper-azole treated.

I treat regulations the same way I treat what seem to be illogical programming/engineering solutions. If I don't understand the problem well enough to know why the regulation/solution is the way it is, I have no business commenting on it until I do.

Very good point. If you're interested, this principle has a catchy name: Chesterton's Fence.

https://en.wikipedia.org/wiki/Wikipedia:Chesterton%27s_fence

You might be thinking of CCA (Chromated Copper Arsenate). It's still in use but harder to find vs. forumations that don't use arsenic.

https://en.m.wikipedia.org/wiki/Chromated_copper_arsenate

I've seen CCA lumber before, but the stuff I'm talking about is different than that. You have to wear gloves while handling it, and if you touch your face you'll be crying the rest of the day. It's nasty shit, but it doesn't rot.

Creosote? Railroad ties are coated in it and for a long time it was one of the main wood preservatives used. It's tar-based, nasty stuff and you'd definitely want to use gloves when working with it.

Good guess, but this wasn't creosote either. It was much more irritating than that. Who knows, maybe it's an especially noxious mix that was only used by sawmills here in the Ozarks? Like I said, we can't find it anymore. My dad had a bunch of 16' 1"x6"s for fence boards in the last batch treated at the last sawmill we knew that could do the treatment, and that was some years ago.

Copper pots have interesting properties. For a long time I had read (and scoffed) that eggs should be whipped in a copper pot for best results. But it turns out that when you do that, striking the side of the pot liberates electrons that bond with the albumin and make the protein stiffer.

As for the comment about silver: it does have some antimicrobial properties. I'm amazed the effect is noticeable at the macro level of eating utensils.

> striking the side of the pot liberates electrons that bond with the albumin and make the protein stiffer

Have a source? I'm curious if one can "cook" an egg by submersing it in cold water through which a current is run.

I think it's the whole copper atoms[1] that get liberated and bind the proteins.

[1] https://www.nature.com/nature/journal/v308/n5960/abs/308667a...

Thanks for digging this up. I should have guessed it was McGee who figured this out. He's an amazing scientist (and cook).

Many families in rural India use copper pots for this reason

Makes me wonder, is there a way to make sure that no copper is still present after the microbes are all dead? Like throw some penicillamine in there to chelate the exact quantity of copper dissolved?

Copper has been used as a biocide in antifouling paints on boat bottoms for decades. The USS Constitution was copper bottomed in 1797.

https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/

Because of copper's antibacterial properties, I investigated putting copper sink faucets in my house remodel. While it's true that it works well initially, over item film builds up on the surface preventing the benefits. You have to clean them constantly to get the benefit.

Uh, copper tube is a common supply piping.

You aren't touching the inside of your copper pipes, you are touching your faucets.

Anyone wanna theorize why? Seeing some of the comments here about silver and gold tells me it might have something to with the high conductivity of these metals.

As electrons flow through them, the germs are dying.

Probably a good idea thus to use all copper pipes in your home!! Using copper vessels would've been great in an era where there weren't industrial pollutants like lead or PFOAs or other things...nowadays in India just a copper vessel wouldn't be sufficient.

In the US as well there are various contaminants in water supplies all over the country from PFOAs to lead so it's a good idea to use a water filter or such. I don't think there's much danger of bacteria in US drinking water.

There was a problem with scurvy when people stored the lime as juice in copper containers and completely removed the vitamin C in the process.

A few years ago GeorgiaTech† created a special anti-bacterial copper alloy (Cu-PANI††), which is now significantly used in the Atlanta Airport drinking water pipings.

[†] https://www.truepani.com [††] http://pubs.acs.org/doi/abs/10.1021/am507746m

What follow-up has there been on this since the 2012 publication in a rather obscure journal? Most importantly, is there a source of copper vessels in most countries that is as inexpensive as other means of reducing bacterial load in drinking water?

So could we also make door handles out of copper, or does it only work for water storage?

Yes, some hospitals use copper plated surfaces with good results: http://mobile.reuters.com/article/idUSTRE76031820110701

we can, and we should. https://en.wikipedia.org/wiki/Antimicrobial_copper-alloy_tou...

In general, hospitals extensively use metal surfaces since the release of most metal ions into the bacteria/surrounding microbiome is toxic. Silver and copper are definitely the best in this regard.

The copper plate on bathroom doors is for this.

Sounds like a way more expensive version of SoDis [0] Why use expensive copper when you could instead recycle, otherwise useless, PET bottles to do a similar job?

The only potential drawback I can think off is that some PET bottles seem to leak "hormone-like chemicals" [1]. Tho, reading trough the comments copper pots also seem to have some toxic effect on the water.

[0] https://en.wikipedia.org/wiki/Solar_water_disinfection

[1] http://www.npr.org/2011/03/02/134196209/study-most-plastics-...

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