Ok calling all chemistry hounds! I know there are many of you on HB!

Currently I cut my tap water about 50/50 with distilled. This gets me into the approximate range for good coffee water. Espresso tastes good, but obviously I could get even geekier about my water (as a gazillion water threads indicate). I test my tap water with a Hach titration kit.

On Instagram Matt Perger suggested this simple water recipe. When I inquired, he also said it would be fine for espresso.

1) Add 25g Epsom and 8.6g bicarb to 500ml distilled water to create concentrate. Shake.
2) Add 2.5g of concentrate to 500ml distilled water
3) Store the rest of the concentrate for later
4) Brew with your deliciously mineralised and buffered water!
(86mg/L bicarb, 246mg/L Epsom for 100gh and 50kh)

Thoughts on this water? Both from a taste/extraction point of view...and also keeping scale to a minimum?

Cheer!

Which bicarb?

I suspect that using any amount of tap water (as you currently do) adds a variable. Ie, tap water can change and unexpected changes are best avoided.

I checked his numbers, and they check out close enough. I got 1.0 mmol/l for magnesium sulfate and 1.01 mmol/l for sodium bicarbonate, which would be a total hardness of 100mg/l and total alkalinity of 50mg/l. (or GH:KH of 100:50 in common parlance.)

I've noticed a few folks on his Barista Hustle slack going with similar recipes and liking the taste.

Since it's all Mg++, and there is no calcium hardness, The typical scaling factor calculations don't apply here. It would produce no CaCO3 scale, and I think there should be no magnesium deposits causing problems at this level.

Only concern re machine health might be the corrosivity. The sulfate concentration of that recipe is 91 mg/l, and sulfates are associated with corrosion. At that level, and with an alkalinity of 50 mg/l, I don't think it's a problem unless you have a vintage machine and are extremely cautious about any potential of corrosion. (Maybe we can have a chemist, like rpavlis, weigh in about that.)

jonr wrote:Which bicarb?
I suspect that using any amount of tap water adds a variable. Ie, tap water can change.

He says he uses distilled, and doesn't say which bicarb, but I'm sure it's sodium bicarb, because the numbers come out right when you assume that.

jonr wrote:Which bicarb?

I suspect that using any amount of tap water adds a variable. Ie, tap water can change.

Sorry, I may have been unclear in my post. I currently use tap water mixed with distilled in my Bezzera Magica (1:1 ratio). I'm not plumbed in and only make 1 to 3 shots per day. So I don't use a lot of water. And, yes, I assume the composition of my tap water changes throughout the year. Since the water where I live is influenced by seasonal runoff etc.

So since I don't use much water in my machine, I'm thinking Perger's recipe could be even better than my 1:1 distilled/tap water method.

homeburrero wrote:I checked his numbers, and they check out close enough. I got 1.00 mmol/l for magnesium sulfate and 1.01 mmol/l for sodium bicarbonate, which would be a total hardness of 100 mg/l and total alkalinity of 50mg/l. (or GH:KH of 100:50 in common parlance.)

I've noticed a few folks on his Barista Hustle slack going with similar recipes and liking the taste.

Since it's all Mg++, and there is no calcium hardness, The typical scaling factor calculations don't apply here. It would produce no CaCO3 scale, and I think there should be no magnesium deposits causing problems at this level.

Only concern re machine health might be the corrosivity. The sulfate concentration of that recipe is 91 mg/l, and sulfates are associated with corrosion. At that level, and with an alkalinity of 50 mg/l, I don't think it's a problem unless you have a vintage machine and are extremely cautious about any potential of corrosion. (Maybe we can have a chemist, like rpavlis, weigh in about that.)

He says he uses distilled, and doesn't say which bicarb, but I'm sure it's sodium bicarb, because the numbers come out right when you assume that.

Thanks for crunching the numbers. I wouldn't know where to begin! Earlier in Perger's Instagram post he says he uses baking soda, epsom salts, and distilled water. Here's the link:


Regarding corrosion, that's also one thing I was thinking about. Since my Magica has a copper boiler. Any idea if Perger's composition would corrode copper?

This is such a simple water recipe and I'd be happy to make it at home if it's suitable for my machine.

Somewhere I have seen comments that potassium bicarbonate tastes better.

canuckcoffeeguy wrote:I wouldn't know where to begin!

Just in case you or someone else would find some hopefully simple instructions useful, here is my go at it:

If you're willing to get used to "moles", it's actually not too bad. (compare to the unit issues in the book "Water for coffee" and it's evident that moles is the right quantifier; it just sounds scarier than it is)

Suppose you want to use baking soda (sodium bicarbonate) for bicarbonate. Then just ask Google:

molar mass of sodium bicarbonate or even molar mass of baking soda

to get the answer

84.007 g/mol

To get the concentration of 1 g = 1000 mg of sodium bicarbonate in 1 l of water, simply divide 1000 by 84 (to get mmol/l).

This principle works for everything I've heard people mix in coffee water, but note that Epsom salt, for instance, generally comes with water in the crystal and Google provides the mass without water. In this case the first link result, gives the mass we're looking for.

If you want the result in mg/l anyway, then just multiply your "mmol/l" with the molar mass of your compound. This way you can easily go between the different conventions for ppm without remembering/checking the conversion factors.

For Perger's recipe, or any other concentrate/two-step method, just multiply all numbers in order to work with 1 l instead of e.g. 500 ml and it should be easy.

I wouldn't put this water in my espresso machine. The sulfate level (over 90 mg/L) is almost twice the maximum recommended by LaMarzocco.

I'd be concerned about the potential for corrosion over the long term, but should be fine to try it and see how it tastes.

For those with questions about his recipe, why not ask the guy directly? I've had one on one conversations with Perger and I'm nobody special. He's pretty approachable.

I did ask him. He said it was fine for espresso. But I wanted to double check with the great minds here on HB. Can't be too careful in my view. Especially since my machine has a copper boiler. And I bet Perger mainly uses high end machines with stainless boilers.

Also he initially posted this recipe as the composition he uses at home for brew. So I followed up with "is this ok for espresso?" But this conversation was on Instagram. Which involves short bursts of banter. See here.

The potassium bicarb is what rpavlis is using, and I'm with him on that (even if I'm not using it), just send him a PM or draw his attention to this thread and ask for his opinion...