I agree with Ike that the first step is to see if there is a statistically significant increase in copper content with what you've got. If there isn't, you're "done".

An HX machine might be better than a DB as you can flush the couple hundred mL before a shot and the water isn't in contact with the heating element. The E61 or any brew head is likely brass, so, if significant, flushing that might be helpful.

Keep in mind that it's the dose that makes the poison.
Unless you have a very serious medical condition, you might be overly concerned.

If coffee won't kill you perhaps trace amounts of copper won't either.

Ask your doctor.

Thank you all for the suggestions! It sounds like testing the water is the way to go. Would anyone happen to have a recommendation? I found this kit:

https://mytapscore.com/products/metals- ... water-test

That looks pretty affordable and comprehensive. I've seen instant copper test kits on Amazon, but my concern is the accuracy level isn't such that the findings would be actionable.

I don't know what your sensitivity is, or the levels that would be considered unhealthy for you.

I do not have any experience with this kit, though I have heard that Hach is a reputable, professional supplier.
https://www.hach.com/copper-free-total- ... 7640217308

It reads down to 0.1 mg/L

The "general population" levels can be found in https://nepis.epa.gov/Exe/ZyPURL.cgi?Do ... 001N8P.txt

Again, knowing the levels that would be unhealthy for you is more important than what the "action level" is for the EPA.

The best place to test your home's water supply is from a faucet at the point where your machine will get its supply of water. Municipal water analysis will give a general idea of copper content in your area, but most of the copper that gets into domestic water probably comes from the home's plumbing system. Many water filters, including Brita, will remove copper, so you could use a point of use filter to reduce or remove copper from the water supplied to the machine.

As regards the leaching of additional copper from machine components, water pH is extremely important. Copper leaching from pipes occurs mainly at acidic pH, so keeping the water slightly alkaline would minimize that risk. As others pointed out, plain distilled or RO processed water should be avoided, as this also encourages metal (not just copper) leaching.

I don't know what copper-related medical condition the OP referred to, but the most common one is Wilson's Disease, in which copper excretion is impaired and copper accumulates in tissues. It is not all that rare. There are also other medical conditions involving metal metabolism (especially iron) for which dietary restrictions are extremely important to minimize health problems. The good news is that coffee itself is considered to be low in copper!

I think everyone is missing a very important point. If using an HX machine, does boiler material even matter? Whether it's stainless steel or copper, the water used to brew coffee does not sit in the boiler. It is pulled from the tank through separate tube that's heated by the boiler. That HX tube that runs through the boiler is ALWAYS copper regardless of the boiler material.

The only time that this should be a concern is if you are purchasing a double boiler machine because the water that will be used to brew coffee will be sitting in the brew boiler. The other time that this might be a concern is if you use the water wand of the HX machine to make a lot of Americanos or teas. otherwise you can just ignore the water feature. Steam is almost like distilling so shouldnt have metal in it.

Rob101 wrote:I think everyone is missing a very important point. If using an HX machine, does boiler material even matter? Whether it's stainless steel or copper, the water used to brew coffee does not sit in the boiler. It is pulled from the tank through separate tube that's heated by the boiler. That HX tube that runs through the boiler is ALWAYS copper regardless of the boiler material. ...

Right, but I don;t think we missed the point of this thread, which was concern over copper in the brew water. An HX machine, as you pointed out, would have copper in contact with the brew water, and dualboiler machines wven with SS boilers could have copper in contact with the brew water if there were copper pipes in the brew path and heated group head (if that is made of bronze).

Rob101 wrote:... That HX tube that runs through the boiler is ALWAYS copper regardless of the boiler material. ...

Not always copper; stainless steel has also been used, and I believe brass as well.

Regardless, copper piping is pretty common inside machines.

I think that the point was missed. People are concerned with toxicity of boiler material on HX machines. The brew water never touches boiler material on HX machines. The brew water goes directly from tank through HX tube which is is always copper even where boiler is stainless steel

Show me one machine where a stainless HX tube is used. It's almost always copper even where boiler material is SS. Point is water in HX machine is always moving and fresh water brought is quickly heated. On dual boiler machines brew water is sitting in boiler. If copper level is a concern you can test this easily: Go to nearest aquarium store and buy the copper test detection kits for $20