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topic 47195

Toxic Lead and chrome in coffee makers and espresso machines?

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47195-3 Ed. note: Click the pic for interesting page about Cremina 67 at www.francescoceccarelli.eu
January 17, 2021

Q. I have a 1984 Olympia Cremina 67. I too had noticed silver and black metal flakes in the water flushed through the group. Opening the boiler revealed what looked like shiny chrome inside the "mushroom" top of the boiler where it was flaking off in patches. The rest of the boiler walls appeared to be oxidized with white crusty spots here and there. I cleaned it off by sanding with successively finer grits of sandpaper, then with wet sandpaper #400, #600, #1200. It's a shiny brass now. I'm concerned now with the possibility of lead leaching into the water, though I am hoping that Olympia built this boiler with a lead-free brass, and have sent them an inquiry. In a nutshell, I plan to soak it for about 4 minutes in a solution of 2 parts white vinegar to 1 part hydrogen peroxide until the brass turns a buttery yellow, which I've read that beer brewer's use on brass parts to remove surface lead.


I'd appreciate any feedback on whether the sanding of the brass may have been a mistake. It seemed to me that I was between a rock and a hard place, since ingesting the flakes seemed unhealthy, while on the other hand, the potential of lead exposure via exposing the brass.

Coffee Kimo
- Northern Massachusetts
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February 20, 2021

A. Just came across the interesting thread. My tuppence worth:

- if you treat your machine with non-approved chemicals, you could cause all sorts of unwanted reactions, including damaging plating and ending up with harmful chemicals you drink long afterwards.

- coffee itself has all sorts of low-level heavy metals and given that espresso machines pass national food regulations, they aren't the problem. I'd either use tested coffee beans or vary my intake and not always drink from one region.

- some people worry about fungus in coffee and bacteria in espresso machines (water tanks and piping particularly). These are likely to be much more harmful -- and faster in their effect on you! Never drink (nearly) non-boiling water from a machine.

- and then there are all the effects of plastics (e.g., the pipes in your machines...) on our hormones.

- You can't win. Enjoy your coffee!

See: pubmed.ncbi.nlm.nih.gov/24340307

Harold Thimbleby
- swansea wales

Previous closely related Q&A's starting in:


Q. Hi,

I saw a related question here, but wasn't fully applicable, so here goes:

I've rebuilt an older commercial espresso machine (Rancilio L6) produced in 1984. I was quite pleased with my work and the resultant tasty coffee, but with all the scares on metal poisoning, I wonder if I'm slowing killing myself, one cup a day!

1) the boiler is made of copper (brass?), and appears to be plated with a dull grey metal (not scale, maybe nickel?). someone has overzealously acid-cleaned/scoured about 1/3 of this plating away inside the boiler. do you think there is any significant lead leaching into the boiler water, or danger from the nickel plating continuing to "flake" off?

2) the portafilter (handle that holds the coffee grounds) is made of brass, and was chrome plated. the chrome is mostly worn away from scouring, but bits remain on the edge. again, is it dangerous to have this chrome plate potentially flake off and end up in the coffee? I've been hearing a lot about hexavalent chromium, although I don't think this is the same stuff.

I know this may be a bit off-topic, but any insights are appreciated.


Bob Schmidt
hobbyist - Palo Alto, California, USA
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A. Bob, firstly, I would not recommend you drink anything that may contain dissolved nickel, but I'd not know if nickel is attacked by coffee; I would suspect not but perhaps someone else can shed light on that point. Secondly, I am not sure where your lead comes from - brass is a mixture of copper and zinc. Thirdly, your question about chromium; this metal is normally pretty non-reactive due to a tenacious surface oxide layer; this is simply why stainless steel doesn't appear to rust - the chromium oxide on its surface protects it. However, again, if it is attacked by your coffee, it may dissolve. I certainly wouldn't drink any liquid that contains flakes of any metal, as it can cause abrasions of the mouth and stomach. However, if it dissolves, the chromium metal will probably be just trivalent, although it could also be numerous other, less common, oxidation states, depending on the dissolving conditions. Personally I would not be concerned, because we all use stainless steel utensils and even drink out of stainless steel cups, so I would be pretty happy to think that normal coffee will not dissolve chromium metal.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

January 6, 2008

thumbs up signHi Trevor,

thanks for response. regarding the lead, I was under the impression some brass alloys may have lead added, or at least have "trace amounts". and I'm not sure why manufacturers plate [pure?] copper boilers with metal [nickel?], I guess to prevent copper reacting with the water (or oxidizing).

Regarding the chrome, I was specifically talking about the chrome plate all over the brass of the filter handles. I don't think this plated stuff is hexavalent though.


Bob Schmidt [returning]
- Palo Alto, California, USA

January 9, 2008

A. Bob,
You are of course correct in saying that lead is added to some brasses. The amount is normally about 2-3% by weight and it is called "free machining brass". The lead acts as a dry lubricant and smears over the cutting surface. This is good for machining brass, but creates a problem if the brass is electroplated because instead of plating into copper or zinc, you are plating onto a possibly poorly adhering layer of lead. Ideally the lead should be removed by careful cleaning prior to plating, but it is not easy to do. Hence, it is best practise to use lead-free brass if you are going to electroplate the material.
Some manufacturers will plate brass or copper to either make it look pretty or perhaps to prevent corrosion. Generally copper does not corrode in water, although there are a few circumstances when that is not true, but for 99.9% of the time, we can assume copper does not corrode. Brass, however, is more likely to, due to attack of the zinc. So, plating can reduce attack if it acts as a barrier between the brass and the water. However, the plated parts will be subjected to thermal cycling between room temperature and 100° C (or more if it is the element that is plated) and this could ultimately result in a delamination of the plated layers from the substrate. Consequently it is not a recommended good practise to plate such components. However, if we assume the substrate is copper or zinc, the most likely plating is nickel followed by chromium. Cheaper plating may just be nickel, but of the article is left in water for some considerable time and then allowed to dry off, the nickel will slowly turn green due to the formation of nickel salts. The time this takes depends on the water composition (tap water is not just pure H2O!). If the nickel is plated with chromium, it will remain shinier much longer.
As far as chromium is concerned, all chromium metal is Cr(0), that is it has no valence, or oxidation state. However, if it is attacked, or "oxidised" to make it dissolve, the resulting chromium salt will be either Cr(III) or some other oxidation state. Chromium can take on numerous oxidation states, but the most "unhealthy" is Cr(VI) or "hexavalent" chromium. These compounds are often seen as orange or yellow in colour. It must be stressed, if you have chromium as just the metal, you CANNOT have hexavalent chromium present.
Finally, I reiterate my comments about metal flakes, namely these should not be knowingly drunk, as they could damage the gastric tract. I would not be too concerned about your coffee attacking the chromium, as we have used stainless steel vessels and utensils of preparing food and beverages (including coffee)for many years and there has been no cited evidence of chromium poisoning from foods or drinks prepared with these tools.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

January 17, 2008

A. If the chrome metal is coming off into the espresso you may have a problem since stomach acid is primarily hydrochloric acid and will oxidize to hexavalent chrome. More likely however is the chrome is flaking when you are cleaning the portafilter. I would be more concerned regarding the lead leaching into your drinking water from the solder which was used to put the pipes together before the advent of lead free solder than from your espresso machine. Anything that is repeatedly heat cycled shouldn't be plated. All metals have different stiffness properties thus will eventually delaminate if they don't form an alloy at the point of contact which will cause migration of the base metal into and through the plating defeating the purpose of the plating.

Brian DeBadts
- Rochester, New York

January 18, 2008

A. Thanks for your participation and comments, Brian. But I do disagree with a couple of things. Stomach acid probably will not oxidize the chrome metal to hexavalent chrome; the two pieces of evidence that I offer are the fact that chromium supplements and colds-easing lozenges would not be sold if ingesting them turned them hexavalent, and Letter 12044, one of the most enjoyable dialogs to grace our pages.

I also cannot agree with you that parts that are repeatedly heat cycled should not be plated. Molds for continuous steel casting are routinely nickel and/or chrome plated, and it's hard to imagine more extreme thermal cycling. Jet engine components are plated. And automobile brightwork which routinely sees -30 F to above boiling temperature as it bakes in the sun is virtually all copper-nickel-chrome plated.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

January 23, 2008

A. I too would question Brian's assertion that stomach acid (hydrochloric acid) will oxidise chromium metal to hexavalent chromium. Hydrochloric acid is not normally considered an oxidising acid, so it would almost certainly only push the chromium metal up to Cr(III). To go all the way to Cr(VI) will take a powerful oxidising agent.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

April 1, 2008

Q. I too am wondering about the gradual disappearance of the chrome plating on the inside of portafilters for my espresso machine. I have never used scouring pads on them, just the usual machine cleaners such as Puro Caff. Clearly the chromium is going somewhere; plating out on my insides perhaps.

Are there documented effects of ingesting small amounts of chromium metal, copper, or zinc over a period of years?

Harley Buettner
- Lafayette, California, USA
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April 2, 2008

A. Hi, Harley. Copper and zinc are not considered "food safe" surfaces. Chromium plating is, I believe, based on the fact that so many food surfaces have been chrome plated for so many decades. It is possible that the surface you are looking at is chrome plated, but possible that it is not. Why do you think it is, besides its shininess?


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

April 3, 2008

Q. The portafilter (the gizmo with the handle that locks into the brew head of the machine) has a snap-in basket which holds the ground coffee for an espresso machine. The portafilter is made of chrome plated brass. Over time, 7 years in this case, the chrome plating wears away leaving the brass exposed. The plating wears away I suppose because of the exposure to water at ~203 degrees, chemical reactions with various organics in the coffee, abrasion due to washing, exposure to cleaning detergents (mostly TSP) and whatever else. I have never used abrasive scouring pads, but clearly the chrome plating has gone over time.

By the way, 7 years of use probably corresponds to 5000 to 10000 double shots of espresso having passed through the portafilter.

I have seen many older portafilters, and they all show exposed brass. Nobody seems to worry about it though.

Harley Buettner [returning]
- Lafayette, California, USA
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February 17, 2012

A. CrIII and CrVI are nearly the only Cr redox forms seen in natural water or even waste water systems. CrVI is highly carcinogenic by inhalation. It is currently debatable whether it is toxic by ingestion. CrIII is a necessary human dietary nutrient. The EPA conducted a Toxicological Review on CrVI (1998) for safe drinking water limits. Most reports indicated that CrVI is primarily reduced to CrIII by saliva and acids of the stomach. If CrVI is able to pass these barriers (generally only at high doses) CrVI may cause liver and intestinal damage/cancers. The EPA is still investigating CrVI carcinogenic ingestion issues but has set the current drinking water standard at 100 ppb (0.1 mg/L). This is the current level which is considered safe to drink without any health risk for average consumption of water every day, over an average life span (~70years).

If your coffee has actually leached chromium from the maker (and the acidity of the coffee has not already reduced any CrVI to CrIII) it is highly unlikely that it has leached such a large enough concentration in your 12 oz drink to have any health risks.

Katherine Linton
- Logan, Utah

May 5, 2012

A. Hi,
It is right the copper has a certain % of lead to make it manipulable for machining, therefore the Espresso machines exported to north america require the nickel plating to comply with the NSF rules; seems the lead from the boiler may be dissolved in the hot water that later will be used to brew you Espresso. In Europe it is not mandatory.

I have no idea about what will happen if you clean the boiler with Acid, and I don't know if it will affect the nickel in the boiler. Make it work for certain time, and make flow water through the group, and take the hot water to a local laboratory, and ask for the metals inside, and compare to the local water regulation for human drinking, if you are out of the parameters, try to get a boiler and pipes from a spare parts supplier.


September 15, 2012

Q. Hello, all!

I know this thread is old but some searching brought me here... I'm restoring an old espresso machine too and the boiler is copper but coated with some metal gray as Bob report his. Inside the boiler, the bottom half is nude copper (probably the scaling over time removed the coating) and the upper half is dark gray. I *suspect* this is tinned copper. It doesn't seem to be nickel.

Just an explanation about this boiler/machine: the water resides inside the boiler under 1 bar (~115íC) and it's used to make the coffe - it goes through a brass group - chrome plated oustside but inside is brass. The filter basket where the coffee puck resides is stainless steel.

I wonder if I should try to remove the rest of gray coat inside the boiler, or if I should look for a new tin coating (not common these days) or even a electroless nickel plating (I've read about the high phosphorus nickel been food safe contact). Water here in Brazil have, in general, low TDS and 7.2 pH. This machine came from Germany, I think the water used was very hard hence so much scaling.

Thank you all!


Marcio Carneiro
- Sao Paulo, SP, Brazil

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Is Mister Coffee expresso machine toxic?

May 22, 2014

Q. I received an inexpensive espresso machine. It's a Mister Coffee. It appears the boiling chamber is lead -- is this toxic under the circumstance of boiling water in it.

Mitch mandell
- Lahaina Maui hawaii
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May 2014

A. Hi Mitch. I'd bet 100 to 1, and probably 1000 to 1, that it's not lead :-)


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Keurig coffeemaker has lead in it -- dangerous or safe?

August 17, 2014

Q. I wanted to ask about another coffee maker. My brother just sent me a Keurig one-cup coffee maker for my birthday. I started reading the Owner's Manual and in bold letters there is a warning "This product contains chemicals, including lead. . ." So now I am concerned that this coffee maker is not good to use. I have searched on-line and what I have found is, the screws inside this item are made with lead. They also claim that the water does not come in contact with them. Do you know anything about these coffee makers?

Thanks for any insight you can give me!


Judie McKitrick
- Troy, Ohio, USA
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A. Hi Judie. I don't feign affection for California's Prop. 65 -- it would be a ridiculous waste of resources even if it didn't do a hundred times more harm than good, which it does. I bought a new gas stove last week plastered with warnings that kitchen stoves cause cancer. I bought a box of screws with warnings to immediately thoroughly wash my hands if (horrors!) my fingers touched the screws. How do you alert mechanics to actual dangers while crying wolf a dozen times a day?

- - - - -
"The whole aim of practical politics is to keep the populace alarmed (and hence clamorous
to be led to safety) by menacing it with an endless series of hobgoblins"
- H L Mencken
- - - - -

Unless you are living in a rather new home, your water is probably running through copper pipes which have tin-lead solder at every joint -- yet due to Prop. 65 you are now focused on where your water is certainly NOT picking up lead instead of where it IS :-)

Lead has also long been used as one ingredient in solder for electronics to forestall the growth of "tin whiskers" which can short out and disable vital electronics, and as a minor alloying metal in brass screws and other brass components to make them machinable.

There is danger everywhere, and reasonable people must work to balance "this" against "that" a hundred times a week -- but that is made needlessly difficult when the toxic government that Mencken warned us about tries to turn each molehill into a menacing mountain, so we would die of fatigue before we could distinguish the real mountains. Engineers are working hard to remove lead and other potentially harmful metals from designs, and I am extremely confident that no water touches any lead in your Keurig coffee maker.


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

August 19, 2014

thumbs up signThanks so much for your input Mr. Mooney. That helps a lot, especially when my granddaughter is taking one to college this week.

Judie McKitrick [returning]
- Troy, Ohio, USA

May 17, 2016

Q. I make an espresso daily at home. I've noticed that the inside of the portafilter that I use has exposed brass while the outside appears to be chrome. The brass imparts a negative taste and stains easily. I'd like to get the PF coated to both improve espresso taste and make for easier cleaning. I do not want to use any fluorine based coating due to a sensitivity. Ceramic ? Enamel ?

Robert Pinarreta
- Mississagua, Ontario, Canada

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July 13, 2016

Q. I hope it is okay to add onto this thread as I'm not having any luck in my search for answers. My question is basically the same as one asked earlier with some additional info that may cause reconsideration of earlier answers: I too have an inexpensive Mr. Coffee espresso maker and am concerned about lead in the boiler. Why? Two reasons really.
1. When I wipe the accessible parts of the metal at the top with a paper towel, it leaves a dark smear on the paper. The appearance is such that my mind immediately says "Lead?".
2. A recent review of a similar, inexpensive espresso maker posted on Amazon wherein the reviewer claims to have purchased a lead test and her water tested negative before and positive after a pass through the boiler.

If this is not lead, what metal or alloy would leave a dark streak with a simple wipe? Thanks in advance.

photo of Jay's expresso maker

Jay Dunn
- Powell, Ohio, USA
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July 2016

A. Hi Jay. Just guessing from the cost of materials and their functionality, I'd bet it's aluminum (which can leave those streaks). That's surely 1000X as likely as it being lead. I don't think you'll find lead anywhere in modern appliances; but if you do, it would be in solder joints. To my knowledge nobody makes parts out of lead for home appliances nor plates them with lead.

I can't explain a lead reading from an unknown reviewer following an unknown protocol on an unknown object; we have thousands of inexplicable results, and claims of alchemy & magic on this site :-)

Luck and Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey

July 14, 2016

Q. Thanks for the response Ted. Aluminum would make sense based on the weight of the unit as a whole. But that still sort of leaves me with the same question: if a visible level of material transfer is so easily produced, what would that say about the water heated therein? Would it likely contain significant amounts of aluminum? (Whether and to what extent ingested aluminum presents a health risk is, I suppose, for a different forum of discussion). There are certainly many aluminum pots and pans available these days, but I've never seen one leave such residue with a simple wipe of a paper towel.


Jay Dunn [returning]
- Powell, Ohio, USA

^- Reply to this post -^

A. Hi Jay. Aluminum can do this, and people also worry about aluminum ... but that's a different subject covered by topic 8962, topic 17519, topic 22551 and others :-)


pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey

September 14, 2019

Q. Hello,
What an interesting thread! I have one more for you. What do you think about hexavalent chromium in coffee grinders? My grinder has a hexavalent chromium prop 6 warning on my coffee grinder. It's expensive, but was made in China.
I promise, I read and get the stances posed about prop65.
I just don't have much faith in the FDA (or in any gov't agency, manufacturing company, trade agreement, or outsourced manufacturing) to protect the population from harm (especially against big businesses). I wouldn't be surprised if there was a risk.
I wrote to the company asking what/where the threat is. No answer yet.
What do you think?
Thank you!
Joelle C.

Joelle Cccc
- Bay Area, California
^- Reply to this post -^

September 2019

A. Hi Joelle. I doubt that the company will write back because anything they say could be perceived as 'diluting the warning', which could expose them to government sanctions and increased responsibility in the event of a suit. It's the state's job to tell you where this hexavalent chromium is which they claim endangers you. But the warnings are not about safety, they're about pandering, so don't hold your breath waiting.

My guess is that the coffee does not touch hexavalent chromium, but that something aluminum or zinc plated in the innards or on the bottom of the unit has a hexavalent chromium conversion coating on it. My name is my bond (it's undersigned).


Ttttt Mmmmmmmmmmmm
- East of the Mississippi, USA

September 15, 2019

thumbs up sign  Thanks!

Joelle Ccc [returning]
- Bay Area, California

December 6, 2019

Q. I have a 1987 Olympia machine and just had new gaskets put on. It's a great machine. But this time when I rinsed the machine -- black thin metal flakes came out. I ran it through a descaler and rinsed it 12 times. Still tiny bits of them but not as bad -- what are they?

deana sidney
- new jersey
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