Readers routinely come to me asking my advice on water filtration. I always tell them the same thing: I don’t filter my water because I’ve had it tested.
Like Jan, reader Graeme got his water tested after I suggested doing that before buying a different, clog-resistant filter. He later sent a quick update: “It came back completely clear. You’ve saved me tons of time and money. NYC water continues to astound …”
It does. New York’s water is justifiably famous for its purity, and the city has gone to extraordinary lengths to keep it that way. But it isn’t the only city that can boast such a thing.
Consult your utility’s Consumer Confidence Report. Here’s New York City’s latest. Here’s Los Angeles’s report. Here are Chicago’s, Houston’s, and Philadelphia’s. You can usually find your CCR on your utility’s website; the EPA can help you find your utility if you’re unsure. (CCRs for the prior year are released as late as July 1, so you may find that yours is from two calendar years ago.)
A few terms to know: MCLG is the Maximum Contaminant Level Goal. It isn’t a requirement, but a level that the EPA or a state agency hopes to eventually achieve. MCL is the Maximum Contaminant Level that’s allowed by federal or state law. (And that brings up an important side point: under the Safe Drinking Water Act, states can set water-quality standards that are stricter than the federal ones. Several states were ahead of the EPA on PFAS limits before the Biden administration tightened the federal standards in 2024, for example. That’s worth remembering now that the Trump administration has rescinded or relaxed several of the standards and enforcement deadlines.)
THMs are trihalomethanes, and are mainly the by-product of disinfectants that are used to reduce bacteria and other pathogens in the water supply. Almost everybody’s CCR shows their presence at some level. How much is allowed is defined by the MRDL, the Maximum Residual Disinfectant Level; how much is aimed for is the MRDLG, the Goal. Most other listings are fairly self-explanatory: lead, mercury, and so on.
To know even more, use a home water test kit. It will tell you exactly what’s in your water, right where it comes out of your faucet. We recommend several Tap Score kits from SimpleLab, both for their ease of use — they come with prepaid and labeled packaging to help you ship your samples to the lab quickly — and for their clarity. The company explains the test results in plain language, flags anything of concern, and has support staff available to answer any questions you have.
This send-away kit delivers lab-tested measurements of more than 100 contaminants, and it explains what they mean and what to do if there’s a problem.
I spoke with SimpleLab founder and CEO Johnny H. Pujol to understand what he has learned from a decade of water testing. He also shared a detailed summary of the data the company has collected.
A lot of people ask about PFAS and microplastics, Pujol said, “but the likelihood is that you’re going to spend a ton of money [on a test kit], and you may not find something that useful or interesting to your home.” (Testing for PFAS and microplastics requires two Tap Score kits in addition to the Advanced City kit that’s our top pick; they cost between $300 and $795.)
No PFAS chemicals are among the 10 most common contaminants that SimpleLab finds in either public (“city”) or private well water, according to the data Pujol shared. Two trihalomethanes — specifically chloroform and bromodichloromethane, both by-products of disinfection at the treatment plant — are among the top 10 in public water. Substances that come from the earth itself — zinc, barium, strontium, and sulfates — are in the top 10 in both city and well water. So is copper, leached from pipes in the home. Glyphosate, the active ingredient in Roundup and many other trademarked herbicides, shows up so rarely that when it does, Pujol said, “our data science team sends a message out — hey, we found a detection.”
And no PFAS are among the top 10 exceedances — instances where the level detected exceeded the company’s in-house health-guidance levels, which are based on EPA and other health-agency benchmarks. Chloroform, bromodichloromethane, and dibromochloromethane, all disinfection by-products, are the top three exceedances in public water supplies. Lead and arsenic are numbers four and five. For private wells, they are numbers one and two.
In terms of overall public health, Pujol worries that forever chemicals are drawing people’s focus away from where it is needed more urgently. “Here you’ve got a concentration that is almost comically low that gets widespread fear and interest — that’s PFAS,” he said. "Whereas the classics — arsenic, radon, lead, nitrate — they don’t seem to get the attention they deserve, and they’re much more significant.”
I didn’t know all of this before I got my water tested, but I knew enough about the US water system, and about my utility’s Consumer Confidence Reports, that I was confident the results would be fine.
Still, I got that little fist of nerves.
Having been president of my co-op in Queens, I was well aware that lead was likely to be present in the plumbing solder. And in New Jersey, there’s a chrome-plating shop — almost certainly a source of hexavalent chromium and other nasty stuff — a block and a half away from my house. Sure, it’s downhill, and sure, my water comes from a reservoir several miles in the other direction, and sure, the CCR showed nothing of concern. But.
So it was reassuring to get the results I expected.
Read the original article
Comments
By BugsJustFindMe 2025-06-0718:076 reply Money quote:
> readings of PFAS that exceed EPA limits have been found in just 8% of small public water systems (those that serve fewer than 10,000 people) and 15% of large ones
15%!
Anyone who trusts their municipal water supply because of *handwave* regulations and reports needs to read that again.
Even if my water were 100% pristine as the author's apparently is, which they only know for their own homes because they've tested it at their taps half a dozen times with different laboratories, my tap water still tastes awful, and maintaining a dedicated three stage filter spout next to my kitchen faucet costs me approximately nothing and provides substantially better tasting water. And I don't need to worry about whether I live in the next Flint, Michigan.
It took two whole years for administrators in Flint, Michigan to acknowledge their lead pipe crisis. What your treatment plant claims it does and what your municipal government claims your safety profile is do not matter one bit if you aren't constantly testing the water actually coming out of your taps.
I'd rather just filter my water. It's much less hassle and I get better tasting water as a nice bonus.
Your filter system is not set up for water that is microbiologically unsafe to drink.
And if that filter setup also has an RO system your cost is more, as with RO you have a certain amount of rejection rate.
By mousethatroared 2025-06-0720:362 reply I trust my municipality to give me microbiologically safe water.
Because I trust bleach, not my local water authority.
I certainly do not trust them to give me chemically clean water. So I have a $150 under-sink RO system.
By rurban 2025-06-086:39 Only third world problems. In advanced societies we don't care about unsafe water because we can drink tap water. (Sure, the US is third world)
Is there a chance it can get contaminated with bacteria? I worry about the water sitting in there.
By mousethatroared 2025-06-0722:001 reply I've thought about this, but I don't think so. My last two paragraphs addresses what I think are RO's risks.
First there has to be bacteria in the municipal water. The city does a pretty good job there,
Second there has to be organic matter for the bacteria to grow. Again, cities are good with that.
But even if you have bacteria in your water, a good RO system's pores should be smaller than a virus (really smaller than a prion) or it won't be able to remove metallic ions.
But let's assume after two years these assumptions fail because the filters get old. Replace the filters and flush the system with bleach.
My fear with RO are bad filters. I once had a Zero pitcher and it tasted bad, acidic. A few weeks later there was a recall that the RO membrane was leaking ionomers.
Moral of the story- trust your senses. If municipal water tastes bad, it's bad. If bottled water tastes bad, it's bad. If RO water tastes bad, it's bad.
From someone that keeps aquariums, municipal water that is stripped of it's chlorine by carbon has the ingredients to grow bacteria. They need three things, carbon, phosphate and nitrogen, all of which will be present to varying degrees. Particularly nitrates and phosphates. They're not harmful until concentrations are really high but certainly enough to grow bacteria.
Also consider what your holding tank and supply to the water, either through leaching, accumulation or simply time
By mousethatroared 2025-06-082:191 reply Now strip it with an RO filter.
By malfist 2025-06-0812:18 RO (without DI) does not remove everything. With an advanced setup like with a booster pump and a 5:1 waste ratio and a high quality filter you would probably see a 95% reduction.
But without a booster pump or if you've got a lower waste ratio either by restriction or piggyback ro membranes you'll have a lower rejection rate.
And that ignores the fact the you really need to be back flushing the membrane regularly and rejection rates are measured after 30 minutes of continuous running, ions migrate when it's idle so you have to throw away a lot of water at the start that you're probably not doing
A properly working RO system will prevent viruses and bacteria from passing. For the extra paranoid you can get systems with a UV sterilisation step.
Just to add, most municipalities chlorinate the water slightly, so its highly unlikely youll find anything alive in it.
My water is fairly heavily chlorinated where i live compared to my previous county.
Letting the glass of water sit in open for a few minutes after pouring helps with taste because the chlorine evaporates.
By vel0city 2025-06-0722:27 If you have a lot of chlorine taste just having a pitcher in the fridge will nearly eliminate the chlorine taste.
By tguvot 2025-06-0720:15 last time i made calculation, it was still cheaper than bottled water
By teruakohatu 2025-06-0723:18 > Anyone who trusts their municipal water supply because of handwave regulations and reports needs to read that again.
A better approach is to decide whether your municipality meets or exceeds guidelines (the 85% that do).
I trust my city (in New Zealand), but there are other cities I wouldn’t because their water infrastructure is old and under funded, or because of known problems in the recent past.
By donnachangstein 2025-06-0719:075 reply > and maintaining a dedicated three stage filter spout next to my kitchen faucet costs me approximately nothing
Calling bullshit on this one. I have one, it's positively wonderful, but the filters are expensive and per the manufacturer's recommendation you're supposed to change them all simultaneously. So when one times out, they all time out. This runs approximately $150 a year minimum depending on usage.
By BugsJustFindMe 2025-06-0719:211 reply > This runs approximately $150 a year
$150 per YEAR at american prices is approximately nothing. That's a measly 41 cents a day.
People spend far far more than that on far far more frivolous things without thinking twice.
By EA-3167 2025-06-0719:55 People spend an order of magnitude (and much more) on coffee every day, never mind smokers or drinkers who spend crazy amounts just to hurt themselves.
Not that I don't love and respect Wirecutter (I don't), but I'm on team "I like how my water tastes when it's filtered."
By kelnos 2025-06-0720:07 I suspect for most people posting here, $150 per year is "approximately nothing".
> So when one times out, they all time out
Some units give you different fixed timespans for each. For that reason, I just use the Reverse Osmosis stage and ignore the rest. RO is the last step, and in theory it renders pure water meaning the only reason to have the previous ones is to pre-filter somewhat the water and extend the RO cartridge lifespan. Problem with that is, first, there's no way to gauge when each filter is spent. Second, they're priced the same anyway, so why even bother. Just go straight from tap to RO! Keep the post re-mineralization stage if you want.
pre-filters typically have specified "capacity" in gallons. which is measurable. also if water is very dirty filters get clogged and pressure dropped. it's also measurable.
"post re-mineralization stage" is actually "ph adjustment".
I know pressure drops. The problem is knowing which filter is the one causing it in particular. Also, filters that are spent at different rates are a PITA. What I mean is if you are going to feed it nominally clean tap water, there's no reason to protect a catridge with equally or more expensive cartridges. Just use the RO filter and be done with it.
By tguvot 2025-06-082:40 you can put pressure guages in between or one of $10 flow meters before system.
RO membrane doesn't remove chlorine iirc or vocs. On the other side chlorine degrades membrane. "nominally clean tap water" can have enough dirt to clog membrane if you don't auto backflush it frequently
It isnt merely ph adjustment... You want some amount of minerals in water for your health, plants, and taste. Changing the PH isnt the concern in most cases, its just part of the result.
All those filters are specifically made for PH adjustment (you are welcome to look at specs). There are bunch of different formulations depends on how much PH adjustment is needed.
RO makes water more acidic. if water was somewhat acidic to start with, it can get more acidic or become corrosive.
The spec doesn't tell you intent it tells you the resulting product performance.
Ph change is one part of the result, not the goal. The goal is water purification.
By tguvot 2025-06-1121:59 i am talking here about post-filters for PH adjustment. their goal is PH adjustments
those for example https://www.freshwatersystems.com/collections/specialty-cart...
or those https://www.freshwatersystems.com/collections/filters-media?...
Are you sure that it makes it more acidic? AFAIK it only outputs pure H20, should be neutral. If you feed it alkaline water you'll get "more acidic" water, but the other way if you feed it acidic water.
yes. it removes calcium and magnesium and it makes water more acidic. also i think it starts absorbing CO2 making it even more acidic.
RO doesn't output pure water. if you want pure water you slap DI filter after RO membrane.
By bernawil 2025-06-082:45 you're right, a little oversight from me.
By mousethatroared 2025-06-0722:041 reply Food gives you all the minerals you need. Matter of fact food can cover most of your hydration needs.
True. But have tasted distilled water? Tastes metalic. Probably just my imagination but I feel like it pulls stuff from the mucous in your mouth and tastes like blood.
By BugsJustFindMe 2025-06-0817:321 reply It is your imagination. I drink distilled water all the time and it tastes great, not metallic at all.
By bernawil 2025-06-0821:39 you sure it's distilled? if you measure dissolved solids with a water quality tester does it read 0?
By mousethatroared 2025-06-0722:03 What system are you using? My five stage filter system has me replace the charcoal filters once a year and the RO every... three? Maybe five?
But let's assume it costs you $150 a year. Thats less than $0.50 a day for drinking and cooking water. I doubt you could buy any significant amount of bottled water for fifty cents.
filters are cheap if you don't use fancy branded system that came up with it's own filter that incompatible with anything else
By an_aparallel 2025-06-0721:141 reply You generally want to avoid cheap filters as they apparently can be tainted with formaldehyde
By tguvot 2025-06-080:34 standard, 2x10 filters from well known brands (pentek, apec or membranes from dow filmtec) are "cheap" compared to non-standard filters.
By dzhiurgis 2025-06-080:06 Have you tested your filtered water in “ half a dozen times with different laboratories”?
By BugsJustFindMe 2025-06-0720:12 You can read the independent test data sheet: https://www.brondell.com/content/UC300_Coral_PDS.pdf
But if you want a full RO system, go for it. They cost only slightly more and just take up more room under the sink.
I'm failing to see your point. If you think it helps -- whether because of taste or personal trust issues or something else -- then great, filter your water. You do you.
The article is clearly for someone who is otherwise on the fence and doesn't have those issues.
By BugsJustFindMe 2025-06-0719:293 reply > I'm failing to see your point
That's weird because I'm pretty sure that my point is explicitly spelled out. But just in case, here it is again:
If your trust is based in municipal numbers or statements, you should be aware that municipal numbers and statements are not trustworthy because there's a lot of widespread decaying infrastructure (and coverup!) between where they test, what they make public, and where your water comes out of your faucet.
And if your trust is based on "Rah, rah, America!", you should know that 15% (!!) of water systems serving over 10k people have PFAS levels measured above what the EPA says is safe. (And if you don't think that 15% is a lot, holy smokes, that's nuts.)
So if you aren't testing your tap constantly then you have no idea what your water is like, no matter what the city says their water is like.
And if you are testing your taps constantly, it's less hassle and gives a better result to just filter your water instead.
The author says "I don't filter because I constantly test my taps and they're good each time." That's not the same at all as saying that filtering isn't a generally good idea, especially for anyone who isn't constantly testing their taps. The author ALSO says "a fuckton of you have more PFAS in your water than the EPA says is safe, just not me, lol". The author also chooses to ignore that their good water today may become bad tomorrow.
By jay_kyburz 2025-06-0721:311 reply Do you test your water after its been through the filters? I'd have some concerns about putting my trust in some random filter company.
By SvenL 2025-06-0721:48 And to that extend do you trust the company creating the test kit? Or their suppliers?
By timr 2025-06-083:14 > That's weird because I'm pretty sure that my point is explicitly spelled out.
Yeah I read it the first time, so repeating it is non responsive. The article was about one person's opinion on the subject of water filters. Your opinion is just one more in a sea of opinions. It's not like the author hid those numbers that you keep repeating -- you're just (again, repeatedly) saying they're scarier than the author felt they were.
> And if your trust is based on "Rah, rah, America!", you should know that 15% (!!) of water systems serving over 10k people have PFAS levels measured above what the EPA says is safe. (And if you don't think that 15% is a lot, holy smokes, that's nuts.)
Yeah, OK. So basically you just want everyone to be as scared as you are.
I don't have a strong opinion on the matter, but your "holy smokes, that's nuts" is worth approximately what I paid to read it. That goes for the author, too, btw.
By rufus_foreman 2025-06-0720:072 reply >> municipal numbers and statements are not trustworthy
The claims of the manufacturers of filters, of course, are completely trustworthy. If you aren't testing the capabilities of your filters constantly, this is fine.
By mousethatroared 2025-06-0722:091 reply I don't trust the manufacturer, but I can test the manufacturers water.
I don't trust my municipality because they cheaped out on the corrosion inhibitors chemistry, leached lead into the water and my house is now filled with developing pinhole leaks. I've had five in four years.
Hint, I don't live anywhere near Flint MI.
By rufus_foreman 2025-06-084:511 reply You can test the filter manufacturer's water but you can't test the municipality's water?
Strange days indeed.
By mousethatroared 2025-06-0811:46 The probability of getting a positive test for lead given that I already know the city messed up and there's lead in the water is 100%.
So why test?
By BugsJustFindMe 2025-06-0720:231 reply You can sue a manufacturer for lying about independent testing and certification. Good luck suing your county.
By rufus_foreman 2025-06-0720:352 reply If you win the lawsuit against the manufacturer, do you get your health back?
The point is they have a reputation to uphold and not just skin in the game but multiple peoples livelihoods.
Just one or two bad test results, or one failed audit, can sink a business like that.
The county can have thousands of people scream for years (flint, Michigan) without panicking.
By cypherpunks01 2025-06-0718:098 reply A surprising amount of Americans refuse to drink tap water entirely, in their own suburban homes with quality municipal water, or anywhere else they travel, holding the opinion that plastic bottled water is safer and better. Of course bottled water is regulated far less than tap water, and contains an ungodly amount of microplastics from manufacturing and storage.
Under-sink RO systems seem pretty great to me, anywhere you live. With a small holding tank, municipal water pressure is enough to drive small RO cartridges, requiring no electrical power to run, and giving more than sufficient flow rate for all drinking water. I think the biggest downside is a few hundred dollars in initial setup, and cartridges every year or two. This seems safer than relying on the changing opinions of experts as to what amount of harmful chemicals are safe to drink.
By BugsJustFindMe 2025-06-0718:161 reply > A surprising amount of Americans refuse to drink tap water entirely, in their own suburban homes with quality municipal water
It shouldn't be surprising that Americans might understand that their water might not actually be safe despite the municipal government saying it is. It took two whole years for administrators in Flint, Michigan to acknowledge their lead pipe crisis. Trust needs to be earned and maintained, and America is notoriously bad at maintaining critical public infrastructure.
> America is notoriously bad at maintaining critical public infrastructure.
How does that compare with food safety in commercial products? That's the question.
By its-summertime 2025-06-086:22 I mean, most bottled waters are transparent, so that compares well against what Flint had
Even if safe, municipal water where I live (San Jose, California) contains a ton of chlorine and is super hard, making it unpleasant to drink. In contrast, bottled water consistently tastes fine.
sorry if this is a stupid question because we don't have chlorinated water in Germany, but do people brew green tea or good coffee with tap water? Doesn't it taste god awful? One of the things which I remember from my holidays in Spain as a kid, which is one of the few countries which adds it here, is that the water tasted like pool water.
By justincormack 2025-06-0719:581 reply Water is chlorinated in Germany [1]. There may be less as ozone may be used as primary disinfectant.
[1] https://www.lenntech.com/processes/disinfection/regulation-e...
At imperceptible levels.
Compared to that, in New York, I can definitely taste it and it took some getting used to. (Ironically, at this point my senses seem to have been rewired to associate the taste of chlorine with fresh, i.e. non-stale tap water.)
By LargoLasskhyfv 2025-06-091:07 Depends on where in .de it is sourced. "Uferfiltrat" meaning from deep wells next to, or near a river, deep wells reaching into other groundwater sources, and dammed reservoirs.
Uferfiltrat=shitty, deep well=depends, dammed reservoirs=mostly good/usually soft water.
Can even vary within larger cities, where different parts get water from different sources.
By donnachangstein 2025-06-0719:00 > but do people brew green tea or good coffee with tap water?
I use filtered tap water (under-sink type) which removes most of it.
A lot of the higher end coffee makers like Keurig have built-in filter cartridges in the water tank.
Most commercial coffee maker setups I've seen (hard-plumbed) in offices have a filter attached to the plumbing behind the appliance.
Water can be safe/potable and taste terrible, and vice versa.
By tomatotomato37 2025-06-0722:381 reply Yes, water quality matters a lot in coffee enthusiast land. They actually make little mineral packets that you add to a gallon of distilled water to get a "perfect" brewing water - I know since I actually use them for my espresso machine to fight scale buildup from my +10 grain tap water.
Note this excessiveness is really needed for espresso though; a regular Brita jug handles more tolerant methods of brewing perfectly well (and to be honest most people murder coffee enough that the water is the least of their concerns)
By miladyincontrol 2025-06-080:42 Just a suggestion as well, theres countless 'water recipes' that let you easily do the same thing for a fraction the price. They arent doing anything complicated. Some mixes are simple two ingredients, some go up to several, but all are pretty dead simple.
Lets you fiddle and fine tune things more for your own preferences too.
By throwaway81523 2025-06-083:23 Third Wave Water is a well known one.
There is a whole book on the topic (2015, with a new edition supposedly coming soon):
By tomatotomato37 2025-06-0722:45 I use "Third Wave Water" but there are other brands out there
By mousethatroared 2025-06-0720:412 reply Its extremely unlikely that German water isn't chlorinated. Perhaps you are thinking about fluorinated?
Chlorine in water is actually fine and tasteless at the concentrations it reaches at the taps - it's basically extremely diluted stomach acid.
The problem is chloramines caused by chlorinated organics. These give water the swimming pool smell and are bad for you.
The solution is easy - reduce the organics in the water before chlorination, and oxygenate (aerate) the water before delivery. But systems can get overwhelmed by too much rain and runoff.
Chlorination of drinking water is indeed uncommon in Germany.
If it’s done, the level is often imperceptible, contrary to the US (I actually had to look this up – I’ve never tasted it in German drinking water in various cities myself).
By mousethatroared 2025-06-0722:141 reply How do they sterilize it?
By ianburrell 2025-06-084:08 Hydrogen peroxide and ozone.
By amluto 2025-06-081:17 > Chlorine in water is actually fine and tasteless at the concentrations it reaches at the taps - it's basically extremely diluted stomach acid.
No. The chlorine in tap water is HOCl + OCl- (it’s a weak acid/base equilibrium). Stomach acid is HCl. And chlorine has both a noticeable smell and odor even at low concentrations (e.g. 1ppm in water). The smell is much worse if any of the chlorine has reacted with organic crud to turn into NCl3.
More enlightened cities in the US use monochloramine (NH2Cl), which is a rather weak disinfectant but is barely noticeable at normal concentrations.
By broken-kebab 2025-06-081:15 Chlorine solubility in water decreases rather quickly with raising temperature. This fact causes me to believe that if one doesn't like his hot-brewed tea made with tap water it's not because of chlorine exactly. I'd suspect calcium or iron instead.
By an_aparallel 2025-06-0721:171 reply My general experience in Australia when i talk about drinking RO water is that im looked at like a crazed madman who drinks "holy water"... So atleast hear i daresay its safe to say the average persons taste and smell must be piss poor
By rincebrain 2025-06-0721:33 You can get inured to just about anything with enough exposure, barring exceptional circumstances where you have difficulty learning to ignore things.
Visiting friends recently, they have well water which smells like sulfur from their tap. Visiting them for a few days, I do not get inured to it, but my friend cannot tell it's there.
By shigawire 2025-06-0718:56 If you drink it all the time you are used to the taste. At least that's how it is for me
San Jose water is absolute trash. There may not be (much) lead, but there are a host of other minerals and contaminants. It’s also a roll of the dice whether you’ll find Legionnaires' disease in your pipes.
I have a whole-house soft-water filter for general use, and for drinking/cooking get 5-gallon bottles filled with RO purified water from The Water Spring on Homestead in Santa Clara. The municipal source for RO water matters, and Santa Clara has the best utilities in the valley.
Stay safe out there.
By LargoLasskhyfv 2025-06-090:421 reply By LargoLasskhyfv 2025-06-0911:11 Dunno. Have been unaware of them so far. Am not that often in SJ anyway, but when I am the tap is taboo for me. That stuff can only be spat out.
I know the Eldorado Springs from when I'm in Aspen, Austin, Altadena, and while I don't get the hype surrounding the stuff, it's more than acceptable (for water).
Taste matters. Be it for coffee, tea, cooking, making desserts, even baking, or making your own pizza dough.
By darth_avocado 2025-06-0718:246 reply One side effect of RO is vitamin B12 deficiency. And there is some debate around whether that is true or not, but anecdotally, I had developed a severe B12 deficiency to the point that one day out of the blue, I couldn’t move one of my legs. I freaked out and went to the ER, and it turns out, 1 B12 shot later, I went back to normal within minutes. The doctor hypothesized that I had developed a severe B12 deficiency because of RO water and that I supplement my food with B12 supplements. The regular intake of meat/eggs wasn’t sufficient to compensate for the lack of B12 absorption.
By eesmith 2025-06-0720:25 The only papers I could find in Google Scholar about this connection all come from India, and does not seem strongly connected. The study at https://journals.lww.com/jfmpc/fulltext/2025/04000/prevalenc... , for example, says:
> While some studies have hypothesized that the use of RO water could contribute to vitamin B12 deficiency, no significant differences were observed in this study.[20] Symptoms of deficiency were not significantly associated with serum vitamin deficiency status. Only VDD was significantly associated with fatigue as a symptom. This discrepancy raises questions about the current normative values for vitamin B12 and vitamin D3 in the Indian population and suggests the need for further research.
A whole lot of people drink RO water. If it were a simple correlation, I would expect to see cases and papers from all across the world.
I also know there's a long history of false claims along the lines "distilled water sucks the minerals from your body", also called "hungry water". I first heard in the 1980s as a supposed reason for not using distilled water in a radiator. Or even commentary of it in the Carnivorous Plant FAQ at https://www.sarracenia.com/faq/faq3385.html .
Because of that long history, and the lack of a good mechanism for how it should work, I need a much higher level of evidence for a direct, causal connection.
What's the mechanism here? Because it's not like there is B12 supplements in the water.
By micromacrofoot 2025-06-0718:483 reply reverse osmosis removes minerals like cobalt, which are used for b12 production
if you only drink ro water it can creep up on you, but takes some time
How much Co is in your water compared to your food. EPA says just 2 ppb in tap water. This means if you drink about 40 fl.oz. per day you only get 2ug of Co from your water. Per the EPA you get about 2-20x more from your food. Pretty much in no cases is your water a source of nutrients.
refs:
https://www.epa.gov/sites/default/files/2016-09/documents/co...
https://www.cdc.gov/nutrition/php/data-research/fast-facts-w...
By miladyincontrol 2025-06-080:461 reply This is my understanding too. There are microscopic amounts of trace elements here or there but in reality none of them add up to anything meaningful compared to what you get from food, multivitamins, or other less ideal means.
Rather if they did there'd be probably quite a lot of concern.
Not sure where that old wive's tale came from but even my parents had similar concerns against filtered water ages ago.
By micromacrofoot 2025-06-0815:02 I've heard doctors repeat it too, though more as an overall mineral deficiency from already poor diets (which is the bigger issue)
By mometsi 2025-06-0718:52 It's not used for b12 production in human metabolism. It is, after all, a vitamin. Is this about cobalt deficiency in dairy and meat animals?
By amluto 2025-06-081:19 We humans cannot synthesize cobalamins from inorganic cobalt.
By mousethatroared 2025-06-0720:431 reply If water is giving you any nutrient in a significant manner, change your diet.
By jandrewrogers 2025-06-0721:372 reply Some essential micronutrients such as arsenic are primarily sourced from water. You don’t need much so most natural sources contain enough. There is actually a valid concern that obsessive over-purification of drinking water can lead to deficiencies of some trace minerals.
Wow this has gone off the rails quickly.
To wit: Arsenic is not an essential micronutrient.
"Trace quantities of arsenic have been proposed to be an essential dietary element in rats, hamsters, goats, and chickens. Research has not been conducted to determine whether small amounts of arsenic may play a role in human metabolism." [1]
By jandrewrogers 2025-06-0722:201 reply There is substantial evidence that arsenic is a required micronutrient in all mammalian biology. This is not even controversial, you can reliably induce deficiency syndromes in a broad spectrum of animal models, and the operative pathways exist in humans. The effect was first observed in animal husbandry in parts of the world with very low background arsenic levels.
It has the same toxicity and micronutrient profile as selenium, another extremely toxic but nonetheless essential micronutrient. Unfortunately, activists with an unrelated agenda have been spreading unscientific misinformation about arsenic to advance that agenda.
Same story as fluoride outrage actually. Being anti-science is fashionable and most people are ignorant about chemistry.
It is one thing that makes me glad I am no longer a practicing chemist.
If what you are saying is true – and I am not being sarcastic - I encourage you to edit and update the Wikipedia page that I referenced.
The authority that I have appealed to (Wikipedia) is a reasonable one and bias should not be implied in the absence of these supposed corrections you have to make.
I’m open-minded …
By maxerickson 2025-06-0821:12 A tertiary source aims to be non-authoritative. Wikipedia tries pretty hard at it.
By mousethatroared 2025-06-0722:131 reply Eat a serving of rice, preferably American, without rinsing it.
Enjoy your 10000% recommended daily intake of Arsenic.
By jandrewrogers 2025-06-0722:34 Background levels are much higher than current standards with no observable effects in many parts of the world. This is well-studied. There is a threshold but it is higher than people assume.
Plant-based arsenic often has poor bioavailability. Quite a few plants people eat are natural accumulators but it just passes through. Pesticides and geology are the primary bioavailable sources.
I drank only distilled water for 16 years. No supplements all that time, just regular food. No B12 deficiency or any other health issues.
By an_aparallel 2025-06-0721:20 My RO system has a remineralisation cartridge. You def dont want to drink ph neutral water, it feels hard, and doesnt taste sweet.
By unyttigfjelltol 2025-06-0718:432 reply Similar risks regarding removal of sulfate from public water supply, or via filtration.[1] Who knew! Some of us were relying on actual nutrients from the water all along. Pristine water was, and is, a challenge for this cohort.
In the linked article, rybett@aol.com uses the CORREL function in an openoffice spreadsheet to determine a weak correlation between autism diagnoses and sulfur content in tap water in a few regions of New Jersey.
His other publications include a self-published amazon book titled Autism, Enzymes and the Brimstone Demons. [1]
[1] https://www.amazon.com/Autism-Enzymes-Brimstone-Demons-Trill...
By unyttigfjelltol 2025-06-0723:54 So does that mean you are persuaded or that the author doesn't have the right pedigree for you to listen? Because when you set aside the author's idiosyncrasies, there is indeed something remarkable.
Drinking sulfate won't repair broken sulfur metabolism, but it's completely plausible that a subset of people maintained adequate day-to-day function with the benefit of sulfate-laden water, and now fall below the threshold with sulfate mostly removed.
By b112 2025-06-0720:04 Interesting.
I'm on a well, but with super hard water. So I have a water cooler, which I empty into a Brita pitcher, but just for drinking.
Just for the flavour.
I cook with my hard water though. Lots of stews and soups too, make bread, etc. So I suspect I get sufficiently mineralised as a result.
For context, I was boiling a large pot of water and got distracted by a call. Most of the water boiled away, well over a gallon. I was left with a solid white disk of calcium at the bottom. Also, when I broke it to get it out, it was super sharp, almost cut myself.
By jandrewrogers 2025-06-0721:141 reply The water in some parts of the US has natural chemistry that makes it unpleasant to drink even though it is safe. California urban areas are notorious for this, as an example. In principle you could remediate the water to make it taste good and remove any discoloration (also a thing in a few regions) with enough industrial processing but that would greatly increase the cost of already expensive tap water.
People who grew up in one of these areas are habituated into never drinking the tap water even if they move to a city with excellent tasting and very high quality tap water. I’ve lived in extreme examples of both.
You also see the opposite case, where someone who grew up with amazing tap water naively grabs a glass from the tap in north San Diego and has a “wtf is this” moment.
By PlattypusRex 2025-06-0721:221 reply San Diego's tap water tastes truly awful. The first time I ever traveled to another city (Denver), I was forced to drink the tap water and could not believe how good it tasted.
By jandrewrogers 2025-06-0721:52 San Diego has the worst tap water for drinking I have ever experienced in the US. When I lived there, pretty much everyone had a reverse osmosis system installed to make it drinkable.
Fortunately, I live in the Pacific Northwest currently, which generally has some of the best tasting water you’ll find anywhere. No one would dream of not drinking the tap water.
In your second paragraph you seem to be describing carbon-block filtration. Particularly, the maintenance of an RO system consists of a lot more than just replacing cartridges every year or two.
By margalabargala 2025-06-0718:432 reply Could you elaborate? I have an undersink RO filter. Maintenance consists of changing filters every year or two.
By an_aparallel 2025-06-0721:23 You need to change filters as recommended, change o-rings, and bleach the fittings. Algae will develop on those. Thats pretty much it.
I wouldnt run bleach through the filters. The filter medium saturates, and any further use will just recontaminate water
you need sterilize entire system periodically. and completely empty/refill tank once in a while
By margalabargala 2025-06-0720:511 reply I totally believe that the system you have requires this, but plenty of others do not.
Here's the maintenance manual for the one I have. The sterilization and emptying/refilling are done as part of the filter replacement, and not otherwise:
https://www.whirlpoolwatersolutions.com/wp-content/manuals/W...
By tguvot 2025-06-0720:57 " Maintenance consists of changing filters every year or two." it's not same as "disconnecting lines and pouring bleach inside when i change filter" or using "Manufacturer recommends using the Model 7301203 Sanitizing Kit"
> ... bottled water ... contains an ungodly amount of microplastics from manufacturing and storage.
Is it worse than the other groceries we can't readily get without them being wrapped in plastic? Or storing leftovers in plastic bags at home?
By s0rce 2025-06-0721:25 My guess is yes, because they can more easily get into the liquid. Unless you are talking about other liquids like juices or canned foods, those I would expect are similar or vary depending on the type of plastic.
By mousethatroared 2025-06-0722:10 A surprising amount of Americans live in cities that cheaped out on the water infrastructure and found out their water had lead.
Like me.
Luckily, I am very unreasonably distrusting of government and never drank the stuff.
By more_corn 2025-06-080:32 Didn’t the Trump EPA roll back water quality rules for forever chemicals? Chemicals that accumulate over time and are known to cause organ failure?
If the federal rules allow unsafe levels of PFAs it’s reasonable to expect that municipal water companies adhere to said unsafe limits. So no we probably should not trust our municipal water supplies.
Maybe in countries that have functional governments that’s a safe bet.
By StopDisinfo910 2025-06-0718:08 I think the writer is sidestepping the main issue most of the people who want to filter their water are thinking about. Sure, your tap water is within the federal limits for contaminants. The issue is that these limits are significantly too high for PFAS out of convenience for the water supplying side.
