Metallic tasting water in my coffee machine

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.

#1: Post by Cristiano »

Hi all!
I am in need of help, if possible. I've been getting a metallic taste in my water coming out of the group on my GS3. This flavor has brought an intense and very noticeable characteristic to my coffee. I have been using water with a very low TDS (25 ppm), mineralized according to the recipe (attached), multiplying by 3 to find the dilution of each concentrate (sodium bicarbonate and magnesium sulfate). Worried about the situation, I tested the alkalinity (kH 3ºdh) and total hardness (GH 1.5ºdh) on the water that comes out of the machine. The two tests were carried out with 10ml of water so that I could obtain greater precision in the results. Despite the amount of minerals added to the water, I was surprised by the low value of total hardness. Do you think these values ​​are correct? and that this result could be the reason for the metallic taste of the water brought about by its low hardness, thus absorbing much of the metals from the boilers and pipes?

I greatly appreciate the help!!

The images below were kindly provided by HB member Michael Herbert who had the full support of fellow HB member Pat.

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#2: Post by homeburrero »

Took me a while to decipher your recipe, but it looks right*.

Your 50 mg/L hardness is about 2.8 °dH. On an API fishcare GH kit with a 10 ml sample should change color at around 5 or 6 drops. Not sure why it measured lower. Besides expired reagents, perhaps may be that the Epsom was not well dissolved or mixed in the sample.

At any rate, even if your hardness is very low I see no way that it would cause a more metallic taste in the water from the machine. I'd suggest trying a water that has the bicarbonate and has no Epsom to see if it tastes better or worse.

* Showing the calculation . . .
Your concentrate is 40.92 grams of Epsom in 1 liter of water. Epsom has a molar mass of 246.5 g/mol, so
40.92 g / 246.5 g/mol = 0.166 mol/l = 0.166 mmol/ml
if you add 45.4 ml of that to 15.1 liters of water,
45.4 ml * 0.166 mmol/ml / 15.1 l = 0.50 mmol/L
One mmol/l of divalent cation is 100 mg/L of CaCO3 equivalent, so you have 50 mg/L of CaCO3 equivalent hardness (all magnesium)
nínádiishʼnahgo gohwééh náshdlį́į́h

Cristiano (original poster)

#3: Post by Cristiano (original poster) »

Thanks Pat!
For all their dedication, clarifications and contributions that they have brought to Home Barista's "water" theme.

Best Regards,

Cristiano Robson.