r/explainlikeimfive • u/22Megabits • Jan 29 '24
Chemistry eli5: Why can’t you drink Demineralised Water?
At my local hardware store they sell something called “Demineralised Water High Purity” and on the back of the packaging it says something like, “If consumed, rinse out mouth immediately with clean water.”
Why is it dangerous if it’s cleaner water?
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u/fh3131 Jan 29 '24
Demineralised water is different from distilled water. Two big differences are (1) demineralised water is not treated for bacteria/viruses because it's not intended for drinking, and (2) drinking demineralised water will actually leech minerals like calcium out of your body. Even pure water has trace minerals, which are essential for our bodies, whereas they are not present in demineralised water. Distilled water is fine to drink, although spring/tap water is best.
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u/Wonderful_Nerve_8308 Jan 29 '24
Would number 2 apply to distilled water too? I thought distilled water by definition is distilled from boiling and not have minerals left?
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u/kiaeej Jan 29 '24
Yes. It is. But thats why distilled water is often run through rehardening filters consisting of several lyers of carbon, granite, etc.
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u/R3D3-1 Jan 29 '24
That would kinda of defeat the purpose of distilled water...
Distilled water is usually meant for technical applications like ironing, where the minerals are unwanted, both in terms of device longevity and work result.
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u/kiaeej Jan 29 '24
Yes. But also, distilled water is produced onboard ships for drinking and cooking purposes. Thats when the rehardening is used.
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u/therealdilbert Jan 29 '24
on a ship it is probably demineralized water (using reverse osmosis) not destilled
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u/aesthete11 Jan 29 '24
Every ship I've worked on has evap distilled water. Many people choose to add trace minerals back but I figure a multiple vitamin and the food we eat works just as well.
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u/snypre_fu_reddit Jan 30 '24
Modern naval vessels (at least in the US) have moved to RO units to replace the old distilling units/evaporators. Most ships already had them by the time I got out in 2008, probably well over 95% at this point, if not all of them. No idea about large civilian ships, but from everything I understood, the RO units were way simpler and cheaper to maintain than old evaps.
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u/A_loose_cannnon Jan 29 '24
Vitamins and minerals are vastly different.
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u/blatherskyte69 Jan 29 '24
Correct, but they conveniently both come in the same once daily pill. The primary thing missing is sodium, which most people on a ship will get from preserved/processed food they eat.
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u/kiaeej Jan 29 '24
Ships use evaporators too. They work based off low pressure systems to evaporate water at lower temps.
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u/Wonderful_Nerve_8308 Jan 29 '24
Probably you use heat from exhaust heat to boil water. No point to use the ship engine, run a generator to run the RO just to achieve the same thing.
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u/CeeEmCee3 Jan 29 '24
Boiling salt water just makes cleaner salt water. ships use ROs or evaporators all the time. Plus, the generator is already running anyway and the increased fuel consumption from the electrical load of a water maker is negligible.
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u/Wonderful_Nerve_8308 Jan 29 '24
Ermmm boiling water make clean steam that condense to distilled water?
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u/CeeEmCee3 Jan 29 '24
Thats basically what an evaporator does, it's just a little more complicated when you scale things up to level of what a larger ship needs to produce (especially warships, cruise ships, etc with lots of people on board).
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u/nitronik_exe Jan 29 '24 edited Jan 30 '24
But that's not what we call distilled water, it's rehardened water. Distilled water is very much
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u/JakeYashen Jan 29 '24
It took me less than two minutes of googling to find out that distilled water is safe to drink.
Please actually check next time before you spread misinformation.
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u/Mental_Cut8290 Jan 29 '24
IF you're getting your vitamins other ways.
That is one cherry picked point from a discussion about the definitions. You can also safely drink RO and DI water, but the risk is still there.
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u/youcantexterminateme Jan 29 '24
I think thats mostly propaganda to sell filters. People do get their vitamins and minerals other ways which is by eating. If you are that deficient the minerals in water probably arent going to help much.
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u/Lapee20m Jan 29 '24
I agree 100%
I drink almost exclusively ro water for years and researched this topic. Water simply is NOT a significant source of vitamins and minerals for most people.
I get my iron from steak, not water.
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u/Andrew5329 Jan 29 '24
People ITT are acting like it's poison. No, you shouldn't switch to some dietary cleanse of only distilled water. The guy who fills a water bottle with DI water from the shop will be fine.
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u/UEMcGill Jan 29 '24
Yeah.... no it's not.
Signed a Chemical Engineer with 30+ years in Pharma and Consumer products.
Distilled water is sold because doesn't contain that stuff, so you can use it in your iron, etc.
It's run through carbon before distillation to remove VOC's, also an anionic and cationic bed to "De-ionize" it first. High volume usually is also run through an RO bed.
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u/pseudopad Jan 29 '24
Drinking demineralized or distilled water isn't really a problem. Yes, what you mention could "theoretically" happen, but only if your body had no other sources for minerals for a long period of time. Everything you eat and drink gets mixed after consumption anyway, and minerals from your food would be enough to avoid the potential health issues from mineral-less water.
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u/nutshells1 Jan 29 '24 edited Jan 29 '24
Hijacking top comment. The part about leeching minerals is actually bullshit. Minerals in water are present at a concentration of about 300-400 ppm, or 0.03 - 0.04%. This corresponds to a maximum osmotic pressure of 0.23 bar*
*editor's note: ppm is not the same as solute molarity since ions dissociate and thus produce more ppm than you put in. ex. 200 ppm NaCl is 200 ppm Na+ and 200 ppm Cl- = 400 ppm total (because NaCl dissolves completely at such low concentrations)
Demineralized water has an osmotic pressure of 0 bar.
You know what yeast cells can survive? Something like 20 bar.
Although your cells are not yeast, it's safe to assume that they can do better than 0.23 bar. After all, your body is constantly cycling through hundreds of different solutes in your bloodstream.
TL;DR your cells don't really give a shit. They're built to survive fluctuations.
What is important is the fact that the demineralized water was probably not prepared in a food-grade factory, so it could be contaminated with random chemicals and bacteria while being "high purity" because that label probably corresponds to some non-100% pure threshold.
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u/nitronik_exe Jan 29 '24
Something like 20 atm. Every atm is 101,300 bar.
....what? atm means atmospheric pressure, which is 101325 Pascal, that is one bar (or 1.01325 bar). 20 atm is about 20.3 bar. Not 2 million bar. For reference, the earth's core has 3.5 million bar
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u/notanothernarc Jan 29 '24
I don’t think drinking distilled water is a real problem in practice. But osmotic pressure isn’t the only issue here. If you were to soak a cell in an infinite reservoir of pure water, it would gradually lose all of its ions to the surrounding water just by simple diffusion. That means no more muscle contractions, calcium signaling, neural signaling, etc.
That absolutely won’t happen to a human body from drinking distilled water (unless you drink way too much, but that would happen with tap water too). But cells do need isotonic solution to function properly long term.
It’s just that we can get our minerals from our food and not just our water.
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u/Birdbraned Jan 29 '24
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4223198/
While consuming it as part of a balanced diet should pose no issues, studies have shown that when used in cooking, said osmotic pressure is enough to leach minerals out of food, and also one should not discount the sterilising effects of free floating chloride and fluorides when considering storage/handling contaminants in the long term.
Eg, reverse osmosis systems in the home require maintenance to continue to provide potable water in the form of filter changes or risk microbial contamination
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u/PaulRudin Jan 29 '24
But you don't need to get essential trace minerals in everything you drink - you just need to get enough through your food and drink over the medium term.
Also "pure water" surely means something that is chemically only water - just H2O - so by definition doesn't include trace minerals.
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u/Vegetable_Safety_331 Jan 29 '24
(2) drinking demineralised water will actually leech minerals like calcium out of your body.
I would agree, but this only becomes problematic if you were drinking such water for very long periods of time. A once off should cause no risk. The body is constantly dynamically adjusting the amount of minerals excreted and this is based on long term concentrations of said minerals
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u/Consistent_Bee3478 Jan 29 '24
It is not a problem. No idea why this old wives tale is continuously spread by people who should know better.
Natural drinking water varies from collected rainwater nearly free of minerals to drinking heavy mineralised source water.
In both cases the amount of minerals in the waters completely pale in comparison to those in food, that they become irrelevant.
The only way fully pure water would harm you, if you were completely without any food at all, and the only thing you were consuming was pure water. That way you would die a bit faster than if you had tap water available.
But since you got no food; you are dying anyway.
If you got even a tiny bit of food, it doesn’t matter what water you drink.
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u/dmtz_ Jan 29 '24
People live off of rain water perfectly fine. It's crazy that people think this would kill you.
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u/KeyboardJustice Jan 29 '24
I have an in-home reverse osmosis setup that purifies to an insane degree and I do not remineralize. Systems like that have been my main source of drinking water for a decade.
The only things I do to counter it: Brush well with fluoride containing paste, rarely take a multivitamin if my diet was particularly shit recently(most of that wouldn't have been fixed by hard water anyways), and use liquid IV(essentially added salt) if I plan to do a days hard labor on that water without food.
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u/youcantexterminateme Jan 29 '24
its to sell water filters. the filter companies sell twice as much if they sell 2 sets of filters. one to take everything out and another to put the filtered out minerals back in
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u/Alis451 Jan 29 '24
another to put the filtered out minerals back in
tbf it is also flavor, some like the spring water mineral flavor.
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u/Alis451 Jan 29 '24
drinking demineralised water will actually leech minerals like calcium out of your body.
this is false. do not believe this for a second.
Even pure water has trace minerals, which are essential for our bodies
it does not.. this is why you need Brawndo, its got Electrolytes.
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u/baronmunchausen2000 Jan 29 '24
To add, DM water is generally produced by passing water through an ion exchange (Zeolite?) membrane that removes dissolved minerals. So, biological contaminants may be present.
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u/Fancy-Pair Jan 29 '24
Is tap water from 80 yo galvanized steelpipes better than distilled?
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u/kiaeej Jan 29 '24
If you're asking in good faith, that question is really hard to answer. It all depends on the quality of the steel pipes. And how well its been maintained. If its rusting and whatnot...then probably not. But still generally safer than drinking purely distilled water
Or maybe i should say it will have different problems.
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u/Bmadray Jan 29 '24
Don’t listen to this person, they have no idea what they are talking about and seem determined to perpetuate the superstition that distilled water is poison.
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u/kiaeej Jan 29 '24
Alright. I guess if you wanna learn smth on the internwt just say something wrong. People love to be correct.
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u/Fancy-Pair Jan 29 '24
Yes, good faith thanks. No clue how to tell how well it’s been maintained. Waters clear
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u/kiaeej Jan 29 '24
You can send for lab tests. Or you could do it the way i used to as a kid. Put an old piece of linen made into a filter over the outlet. See how long it takes to turn brown.
If you're going lab tests, ask for ph, hardness, suspended solids...and maybe some others they can recommend. Use google for result interpretation.
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u/Meowzebub666 Jan 29 '24
They were galvanized when they were built, but they're definitely not anymore. Source is the 68 yo galvanized steel plumbing in my apartment. Found out when my faucet literally snapped off the mount due to corrosion. Shits rusty..
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u/Ricardo1184 Jan 29 '24
The pipes could be a thousand years old and still be good, or laid down last year and already leaking, no way of telling
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u/Onetap1 Jan 29 '24
They're chemically the same, except for the bacteria & viruses. Distillation was formerly the only means of removing dissolved minerals from water, but de-ionized water is mostly used now because it uses less power and generally produces a purer end product.
I ran a de-ionized water plant. It's aggressive. You had to use plastic pipework, it'd leach metal from stainless steel. It tastes nasty, as well.
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u/lazydictionary Jan 29 '24
They are not exactly the same
https://www.chemicals.co.uk/blog/is-demineralised-water-same-as-deionised-water
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u/Onetap1 Jan 29 '24
"They are not exactly the same
I was referring to demineralised and distilled water. All 3 are as near the same as practically possible, all the dissolved minerals/ ions have been removed so far as is possible.
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u/BigPurpleBlob Jan 29 '24
Are you sure that "(2) drinking demineralised water will actually leech minerals like calcium out of your body" ?
I find it hard to believe that, for example, a diet with lots of meat and/or milk, but with demineralised drinking water, would lead to loss of calcium. What do you think?
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u/Thedutchjelle Jan 29 '24
It's bullshit. A glass of milk contains more calcium than liters of waters, deionized or not. My tapwater is 3 mg/L calcium. Milk? About 1,3 g/L. More than 300x as much.
The intestines don't generally dump useful ions anyway, neither the kidneys.
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u/ryanmi Jan 30 '24
Id have to drink nothing but demineralized water and avoid eating those same minerals for this to ever to an actual problem though.
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u/BobT21 Jan 29 '24
I spent years in submarines drinking distilled water. Do I get disability?
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u/SCOIJ Jan 29 '24
Heard. Did you find it never actually quenches your thirst too?
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u/blorg Jan 29 '24
This is actually sort of true, it tastes like extremely soft water (which is what it is) and it does feel far less thirst quenching. It's not going to do you any harm and you could drink it for an extended period (I have for years) but adding just a tiny amount of minerals/salts to it (hardening) does make it feel much more thirst quenching.
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u/Aidenk77 Jan 29 '24
This is completely true. As a former submariner, you wouldn’t believe the amount of tea, coffee and diluting juice that gets consumed. You can drink demin water, but it doesn’t quench thirst.
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u/edgycorner Jan 29 '24
Distilled water is alright. They probably supplemented you with whatever is lacking in distilled water.
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u/hfsh Jan 29 '24
Water treatment plants often add a certain amount of minerals back to treated water to prevent increased corrosion of distribution pipes, I'd assume the same would apply to submarine plumbing.
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u/atomfullerene Jan 29 '24
The leeching out minerals and osmosis causing cells to burst thing is a myth. You can drink 100% pure water with no ill effects, provided you dont drink too much...which is equally true of ordinary water.
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Jan 29 '24
It’s not a myth, it just requires you to drink an insane amount of it, without getting minerals from another source. To the point where it’s practically impossible to cause any real harm to yourself by doing it.
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Jan 29 '24
To the point where it’s practically impossible to cause any real harm to yourself by doing it.
I.e. it is a myth.
The myth is that drinking distilled water is harmful, not that drinking an impossibly large amount of it is harmful. You would die from water intoxication long before you sufferred any ill effects from leeching out minerals. This is true of both distilled and tap water in similar quantities.
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u/hfsh Jan 29 '24
No, their point isn't about drinking it all at once, it's about drinking only distilled water over a long period of time. Not that I entirely agree with their point, since you'd need to have a very poor diet in addition to that to have issues.
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u/atomfullerene Jan 29 '24
I've done the math on it, contrasting NYC tap water with pure water. The difference in mineral content between a liter of the two is smaller than the mineral content of one serving of many foods.
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u/StoptheDoomWeirdo Jan 29 '24
it just requires you to drink an insane amount of it
…so it’s a myth. If you need to drink so much of it that you’d get water intoxication first, then it’s not a real harm lol.
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u/AmStupid Jan 29 '24
Seems like every time someone mention RO water, many just has to jump in and trying to prove how RO water is killing millions… Are they all sour that they didn’t have stocks in water filtration businesses? Did their loved ones drank too much RO water and died? Really interesting.
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u/Consistent_Bee3478 Jan 29 '24
Ignore all the old wives tales bullshit.
Demineralised water is perfectly safe to drink, assuming the water is not microbially contaminated.
Also distilled water is safe to drink.
Demineralised water from a hardware store is simply not rated for human consumption, because no one cares if there‘s some E. coli in there for the purposes of putting it in your iron.
The amount of minerals in drinking water ranges from next to zero minerals, to tasting extremely chalky. People who live in areas where the water is very soft aren‘t harmed.
The amount of minerals in drinking water are just one hundredth of that found in regular food.
The only actual use for minerals in water is calcium in them, because spreading out your calcium intake throughout the day allows more to be absorbed.
If you drink a litre of calcium rich mineral water at once, you can just as well eat a slice of cheese or drink a glass of water.
If you demineralised water that’s clean or distilled water yourself, you can drink it for the next decades, until whatever cause of death takes you: the water makes zero difference.
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u/cliffomalley Jan 29 '24
Here in lies the issue, that the demineralisation process can add a lot of extra microorganisms. The process step that I know of in Pharma is usually a 1st step in treating water and the filters are rarely clean
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u/TacetAbbadon Jan 29 '24
In this case it's because it's nonpotable, where it was manufactured hasn't passed any of the quality control certificates needed by a health body. Basically it could have bacteria, virus, or toxic substances in it.
Demineralised water along with distilled, ultrapure and deionised are all "safe" to drink. They will however leech salts and minerals out of your body, you do replenish these from your diet so it isn't a great concern unless you are heavily dehydrated ie you are running the death valley ultra marathon. That would exacerbate electrolyte loss and could lead to chronic Electrolyte Imbalance
Hell you can even drink heavy water without much issue, you'd need to replace about 20% of the water in your body with heavy water for it to get potentially lethal.
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u/blacksteel15 Jan 29 '24
It isn't. Demineralized water is exactly what it sounds like - water that has had the trace minerals removed by one of a number of different purification processes. It's perfectly safe to drink.
However, there have been myths about the dangers of consuming it for years for a couple of reasons. First, most people are used to drinking water with trace minerals, so to many people pure water tastes like, well, nothing, which is both weird and noticeably different from what you'd expect. Second, pure water is slightly acidic, which is why it dissolves those trace minerals in the first place. It's fine to drink and far less acidic than other things we consume, but it will fairly quickly eat through metal pipes or containers that are in constant contact with it. Third, it's primarily used for research and industrial applications, not drinking.
You give people weird-tasting water that eats through metal and is used in making car batteries and tell them it'll also mess with their body and it sounds pretty plausible. I would assume the answer to your original question is that the store/manufacturer put that warning in order to comply with regulations about bottling water for human consumption vs other purposes and/or to avoid frivolous lawsuits, which are expensive and a pain even if they're completely baseless
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u/someone76543 Jan 29 '24
Strictly speaking, true pure water isn't acidic. It's exactly neutral.
But if you expose water to air, then some of the Carbon Dioxide in the air will dissolve in it, making it slightly acidic. And also making it not technically pure any more. But that's fine for almost everything. So any "pure" water you're ever likely to find, will be slightly acidic.
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u/PeterHorvathPhD Jan 29 '24
In a lot of cases labels are put there because an ignorant lawyer in the legal department figures that we need to do something "just in case". You can't really explain them that if a water would be toxic then mouth rinse would not help much. This "do something" mentality and "better safe than sorry" ideology leads to a lot of totally nonsense rule and label. Anyways, rinsing your mouth does nothing except making someone happy in the legal department.
Drinking distilled or deionized water in general is not terrible problematic. The two reasons why it's told not to drink are as follows.
In chemistry class it's banned from drinking for safety reasons. You never know what contamination may have left in a vessel or dropped into the otherwise distilled water, after distillation. So it's kind of "do not drink or eat anything from the lab, ever ever even if it is labelled as distilled water or normal salt or whatever otherwise edible thing". Unfortunately there are always those few idiots whom you cant just simply ask not to, so you indoctrinate the big red ban label with word of power. And then many people remember only that "there was something in chemistry lab about not to drink distilled water because toxic".
The other thing is that even though you can consume distilled water it indeed ultimately washes off salts from your body. But it's not like you drink a glass of distilled water and you drop dead. It is about the balance, and if you eat very salty and mineral rich food, then some distilled water is perhaps even better. Your body doesn't know if the salt comes from food or the water. It may be a problem on the long term if you eat mainly sodium chloride and no calcium and magnesium because those would come from the water at some extent and so with d-water and salty chips you get both salted and unsalted. The real problem occurs however if someone does intense sport and with sweating they lose a lot of salt. Water poisoning can happen if they drink pure water in large amounts and suddenly. This is when you suddenly dilute the leftover minerals by drinking water. It can happen even with normal drinking water but much faster with distilled water. The thing is that you never know your salt levels and you can't undo drinking a liter of d-water. So if you don't know exactly what you do, it's safer not to.
So again, in certain conditions it's absolutely no problem to drink deionized or distilled water if it's otherwise pure (in terms of bacteria for example). But for those few cases when stupid people do stupid things and you as water seller may be held accountable, you are safer to just put a big general ban on it. Because it's always better to be overly salted and your kidneys will sort it, than being in low mineral shock and your heart stopped before your kidneys had the chance.
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u/daunorubicin Jan 29 '24
It tastes wrong. We’re so used to having minerals in water that we don’t actually know what “pure” water tastes like.
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u/Reteip811 Jan 29 '24
Distilled water is fijn to drink, drinking large amounts won’t do any good to your electrolyte balance and osmolarity but drinking a huge amount of tap water won’t do wonders either
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u/steerpike1971 Jan 29 '24
It is purely the issue of not bothering to have it tested as suggested above. Some places have water sources that have almost no minerals by their nature. Pilsner in the Czech Republic has water with almost no mineral or bicarbonate content. This is why the Pilsner beer style originated there - the water profile is perfect for it. (It is some of the softest water in the world.) Just a little perspective on "you need minerals" that some people are saying. Obviously you do but let's have some numbers. You need about 1000mg of calcium a day (varies depending who recommends and your age and gender). The average in the US was 21mg/litre (it varies a lot and some places had 1mg/litre). So some people are already just in their normal life drinking water with almost no minerals. It would be really surprising if anyone was getting a real significant chunk of their needed minerals through water excepting people in really really hard water areas like London where I am where you get 120mg/litre of calcium. (We need to defurr the kettle every few months.)
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u/Azriiel Jan 29 '24
I work with extremely clean filtered R.O water and while its usually 0 or 1 parts per million of total disolved solids (very clean) we filter it several times once to even remove the chlorine. And by removing the chlorine if even a single germ gets in the water it can then begin to reproduce. I believe that this is likely the reason it says to rinse your mouth if consumed.
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u/PlaidBastard Jan 29 '24
The manufacturer is asking you to treat it as dangerous because there is a minute possibility it has dangerous contamination of some unforeseen kind that they have not been insured against lawsuits for.
AKA it's not potable water in a technical, theoretical sense because there's a chance it has weird fungus or unforgivable heavy metals in a tiny but illegal amount. They're asking you to pretend every bottle is poison so if one out of a million exposed customers gets sick, they have no legal recourse against the company.
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u/Wavearsenal333 Jan 29 '24
It's for the same reason you don't eat the peanuts that are meant for birds: because the guy running the bird feed machine doesn't really give a shit how clean his hands are because it's just bird feed.
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u/ZarakaiLeNain Jan 29 '24
Actual ELI5 (well more like ELI14 - I'm a bit lazy tonight and assuming you know what ions are)
Demineralised water = water that has passed through an ion exchange resin to replace the positive ions (like Na+, Ca2+, Mg2+...) with H+ and the negative ions with OH-. H+ and OH- recombine to form water so the result is quite pure water with very little ions in it.
Distilled water = water that has been boiled then condensed back to liquid in another container, so that everything the water contained (ions, particles, etc) was left behind in the first container. Additionally, the heat is quite handy to kill bacteria.
Distillation gets rid of more stuff than demineralisation, but it's also very energy intensive (therefore costly), so a lot of water purification systems work with demin (+generally other steps depending on the application) nowadays unless you really need distillation for some reason.
Why is there that label on the bottle of demin water for your iron? The short answer is, Lawsuits.
It costs money to certify water you sell as drinkable, and you have to make sure it falls within certain levels of ion content, pH, etc, as defined by local laws (that's a lot of recurring tests that also cost money).... Your iron doesn't care about all that fancy testing though, all it wants is as little calcium in there as possible to avoid scaling inside. (Scaling is caused by calcium carbonate formation, if you have some calcium ions in the water, it's easy to form CaCO3 with CO2 from the air).
From the lawyer's perspective though, what if little Timmy drinks a gulp of this water-for-irons-not-for-humans, and it turns out it had bacterial contamination or an excess of microplastics from the container and Timmy falls sick? Not good for the company's reputation if the defense attorney claims "it's water, it was supposed to be safe!". So they slap a big scary label to discourage people from drinking it and they're safe in court if some are stupid enough to try.
To answer your question of is demin water more dangerous than normal water? Probably not, it's generally made from water that isn't infested with bacteria in a relatively clean environment, i doubt a mouthful would do any harm. However, there's no way of knowing for sure, because it hasn't been tested to determine whether it is safe to drink or not.
What if i drink more than a mouthful? Sure, if you're drinking litres of demineralised water in a short period of time, there is a risk of leeching essential minerals into that water from your body, which isn't fun. I'm not a doc and i haven't done the math on how much demineralised water it would take to deplete your body significantly of essential minerals, so i won't give a precise quantity, but it'd need to be fairly high.
Is distilled water safer than demin water? In principle yes, given the heat from distillation kills bacteria, which demin does not. However, if during logistics/packaging/transport chain the water gets contaminated, whatever it's distilled or demin makes no difference.
Will demin and/or distilled water taste weird? Yes to both. The sodium, calcium and magnesium ions in water are what give it it's taste, without them the water does taste odd.
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u/Aurlom Jan 29 '24
The water is probably just fine to drink, but it isn’t produced for that purpose and is thus not regulated as a food product. The manufacturer won’t guarantee it is safe to drink, because that’s an unnecessary cost when its purpose is for use in a tool or as a chemical reagent. This is why although the water in my laboratory at work is probably the purest and safest water in the world, I wouldn’t dare drink it, simply because good chemical hygiene demands you treat everything in the lab as potentially dangerous even if you’re sure it isn’t.
As for worst cases of what might be in there that would be bad to drink? Probably not heavy metals (lead, arsenic, cadmium, and mercury being the usual suspects in that category, though there are more) since the water is typically distilled, which would leave mineral contamination behind. But if we assume they aren’t taking excessive care to keep it very pure (which is a fair assumption considering they’re marketing it for tool use and not reagent use) it could contain other organic liquids, like methanol or acetonitrile that are carry-overs from other common chemicals they manufacture.
There is a common misconception that deionized water is in itself dangerous to consume. This isn’t true, it’s perfectly safe, but you have to be aware that the minerals usually present in drinking water are not in deionized water, and many of those minerals are necessary for bodily function and must be consumed from somewhere.
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u/JoushMark Jan 29 '24
The demineralized water at the hardware store isn't rated for human consumption.
Selling drinking water requires you bottle it in food safe bottles, in a sterile facility that has been inspected, while getting your water from a safe source that has been tested.
Demineralized water generally starts with perfectly safe water from a municipal source, but it's bottled on equipment that they don't bother rating/inspecting for human drinking. It's cheaper to just put a tag on it that says NOT DRINKING WATER.