Brewing water for COFFEE

I'm new to brewing water chemistry, have read through much of the sticky at the top of this section on the subject once, but can definitely stand to refresh myself on it. However, I have a question about a bit of an off topic water chemistry subject. Specifically that of coffee brewing water.

I have some general goal numbers (TDS, pH, Alkalinity & Hardness) which I'll post at the end, but is this enough information to adjust RO water if I know my starting points? Or do I need to know specific ions like used in BeerSmith and other calculators (Ca+, Mg+, etc etc)?

From "Everything but Espresso" by Scott Rao, the recommended water chemistry for coffee is:

TDS - 120-130ppm (mg/L)
pH - 7.0
Hardness - 70-80 mg/L
Alkalinity - 50 mg/L

 

I drink a latte as opposed to coffee in the morning. It's pretty simple really, I make some espresso and dump it into some milk I heated in the microwave. I've got my method down to the point that I can make a big ol' over sized cup of this faster than most can brew regular coffee.

As for the water chemistry. I've done it two different ways. Using tap water to make the espresso and using bottled water. I can't really tell much noticeable difference either way. Because of this, I simply use the tap water most of the time. Maybe I have really good water? Perhaps, I use this same water to make beer and it has always turned out pretty good too.

Sometimes I find the temptation to dive into details isn't well founded unless your end product shows a fault suggesting there is a problem. I know that isn't very helpful to you, I apologize in advance.

Hopefully the coffee experts will chime in soon with more specific numbers and details. I think there is even a coffee related sub-section to this forum where you can post questions that might get the attention of coffee experts as well.

 

Yes, you can do this. To 1 L DI water add:
29.25 mg of anhydrous CaCl2 (or equivalent of one of the hydrated salts)
48.64 mg of CaCO3 (chalk)

Fit an aeration stone to a CO2 cylinder and bubble CO2 through the water while stirring until pH reaches 7. This will take several days. Or put water and salts in a PET bottle, pressurize to a few atmospheres with CO2 and shake until water is clear. Remove from pressure. Agitate until pH rises to 7.

TDS is going to be below the spec so add anything you like to get TDS up e.g. NaCl.

 

I've done a smidge more research since my original post here. And just recently delved into this a bit. For a refresher, ideal ranges are:

TDS: 120-130ppm
pH: 7.0
Hardness: 70-80ppm
Alkalinity: 50ppm


I pulled 1gal RO water which gave:
TDS: 24ppm
pH: 7.9
Hardness: 8.85ppm
Alkalinity: 17.9ppm

I added a 2 part product from Global Water Solutions called "AB Formula" which is supposed to bring RO or distilled water into ideal mineral content for best flavored extraction out of brewed coffee. As per directions I added the two vials one at a time to my 1gallon of RO water which brought my numbers to:

TDS 165ppm
pH: 9.8
Hardness: 107.4ppm
Alkalinity: 62.65ppm

As you can see, pH skyrocketed for my preferred 7.0pH mentioned in the original post, along with the other parts, so I diluted with about 1/2gallon more RO which got me on the low end or within range on all except pH:

TDS: 110ppm
pH: 9.7
Hardness: 71.6ppm
Alkalinity: 53.7ppm

To attempt to drop the pH and a little room to raise the TDS, I added a 0.15g Calcium Chloride and 0.13g Calcium Sulfate which gave me:

TDS: 178ppm
pH: 9.5
Hardness: 161.1ppm
Alkalinity: 49.2

My pH DID drop, but almost negligibly, especially compared to completely overshooting my TDS and Hardness.


Is there a way to drop the pH much more significantly without bumping up the other numbers so much?

I know it's tempting to say "Just don't add the AB Formula stuff" but I'm not sure of the mineral content of it (proprietary) or the ideal mineral content for coffee in general to mix my own from scratch.

 

As I mentioned in an earlier post you would make water to this spec from DI water by adding 24.4 mg anhydrous calcium chloride, 27.8 mg sodium chloride and 48.0 grams of calcium carbonate to each liter of water, dissolving the chalk with CO2 gas under pressure and removing excess CO2 to set pH to 7.0. This time I set the solver the specs exactly as you wrote them i.e. any TDS between 120 and 130 (it went to 130) and any hardness between 70 and 80 (it went to 70) would be acceptable. The sodium chloride is in there only to raise the TDS. You have to use CO2 to dissolve the chalk. If you could accept alkalinity of 47 you can use phosphoric acid instead of CO2.

You are asking somewhat naive questions about water chemistry and at the same time are stating the hardness and alkalinity of RO water to 2 decimal places. I have to ask how you measured these and the pH.

Accepting those numbers as correct the weights per liter for the salts change to

CaCl2.0H20: 25.8 mg/L
NaCl: 17.9 mg/L
CaCO3:37.9 mg/L

TDS: 121
Hardness: 70
Alkalinity: 50

Apparently there are tow 'ideals'. You will have to choose the one you want.

DIlution will dilute minerals e.g. a 2:1 dilution with DI water will change the concentration of sodium, potassium etc. to 1/3 of their pre dilution values but it does this only approximately with alkalinity and not at all linearly with pH. Again I am curious as to how you are measuring pH, hardness and alkalinity.

Yes. Add hydrochloric or sulfuric acids. They will change the pH and alkalinity.

If you don't know what you are trying to hit you are going to have a bit of a struggle in hitting it.

 

ajdelange - I apologize for my naivety. As I said in the first sentence of the first post of this thread, "I'm new to brewing water chemistry" and literally by definition, anything I mention on the subject would be naive. I also apologize for neglecting your original post. I read it and appreciate, now both of your replies, but do not have the means to use pressurized CO2 to dissolve chalk (yes I saw your phosphoric acid suggestion and will look into it).

As far as my significant figures go, I neglected my intro to chemistry class guidelines when doing the math. Basically assume 1 decimal place or less on all numbers if that is a factor in answering my question. I'm using small inexpensive handheld meters for pH and TDS and equally inexpensive aquarium titration kits for Alkalinity and Hardness (KH&GH) which are based on number of drops in a 5ml or for slightly more accuracy 10ml samples and referring to their provided chart.

I'm sorry for the confusion on the ideals. It's the same issue which relates to the last comment about not knowing what I'm trying to hit. From multiple sources, my ideal numbers were as stated in my original post and restated at the top of my second post. The manufacturer of the AB formula product has an unknown (to me) definition of ideal coffee brewing water which when I used the product did not fall into MY target numbers, but was being used as a starting point for me.

 

There is certainly no need to apologize. I asked the questions I did because it helps to know such things in formulating an answer. If you say you use drop count kits that's one thing but if your answer is 'my brew buddy has access to an ICP machine' that's another.

 

Before you get too crazy with the water modding, perhaps you should check what type of water YOU prefer for YOUR coffee. As a beer and coffee nut, I simply refuse to believe there's an "optimal" water profile for coffee water for everyone's tastes, for all levels of strength, and all types of coffee and roast levels. No way.

In fact, I've made my daily coffee with 100% distilled and with 100% Chicago water (110 alkalinity as CaCo3) and don't think I could tell the difference. Using unfiltered water absolutely ruins the coffee, but the effect of minerals seems very minor. In short, unlike beer, there's so much other junk in your cup o' joe that minerals become just noise. It's an interesting topic, no doubt, and I'd like to know more about it. But I get skeptical at any mention of "optimal" or "best".

 

Dear Speedyellow,

Please excuse my effrontery - but I am registering here and replying only to challenge your post. I am prompted to do so by two things: first, you describe yourself as a 'coffee nut'. At the very least, from this infer that you take your coffee seriously. Secondly, and not under your control, ajdelange, who has made a lot of good sense up until now, has put a 'like' on your post. After reading your post, I had to ask myself, 'what is there to like?'

I must take issue with your statements that, "there's so much other junk in your cup o' joe that minerals become just noise" because it leaves a lot of room for interpretation. By 'junk' one may infer that you are raising the point that coffees are an unknown mixture of mixture of polyphenols, diterpenes, caffeine, and many other moieties, or one may infer that you mean that the brew process introduces chemical and breakdown contaminants. Either way, minerals are not just noise; they have been proven time and time again to modulate that appreciation of a cup of coffee.

If you were to describe in detail your coffee making, including the manner of brewing, the type of roast, the age of the roast, how stored, how ground (do you grind your coffee or use pre-ground?), water temperature and your ratio used, we may get to the bottom of why coffee made with distilled water and tap water taste the same to you. Please do not think that this is an attack on your taste discrimination because the answer may be found in the way the coffee is made. Please search the coffee specialty forums by adding the terms "site:coffeegeek.com" and, alternatively, "site:home-barista.com" without the quote marks to a Google search that also includes the terms "distilled water", with the quotes and "taste" without quotes and you will quickly find that there is universal agreement that coffee brewed with 100% distilled water is not fit to drink, at least among self-described coffee nuts.

I am interested that you mention that unfiltered water produces a brew that is unsatisfactory to you, but unfiltered what kind of water? Any what manner of filtering? You say that you are making your daily coffee with either DI or tap water. Since one doesn't need to filter DI, then are you filtering the tap water? So are you comparing no taste difference between DI and filtered tap water?

When the above brew parameters are carefully noted, and tweaked to produce a satisfying cup of coffee, one becomes aware that the taste of a cup of coffee balances delicately on so many things, including the chemical profile of the brew water and, the latest revelation, the temperature of the whole beans that are put into the grinder:

http://www.home-barista.com/tips/so...on-wbc-finalist-dawn-chan-kwun-ho-t35328.html

If the fine details of coffee brewing are too cumbersome for a person to bother with, please understand that there are persons for which this is not true. And since you state that you might like to know more about it - and I warn you, this could be the start of an on-line reading course that can take a week or so to finish, if interested - you might start with two of the more widely read posts by the 'two Jims', James Hoffman and Jim Schulman:

http://www.jimseven.com/2010/11/28/fear-of-water/

And "Jim Schulman's Insanely Long Water FAQ":
http://users.rcn.com/erics/Water Quality/Water FAQ.pdf

Your relationship with a glass of water will never be the same.

In closing, let me agree with you whole-heartedly that there is no one formula for optimal or best.

Buckley

P.S. @RWings39: If your RO water is coming out with a TDS of 24, it is not RO water. Check your filter or set up.

 

That's the bit I liked.

 

Roger that. Amen.

 

BuckleyT,
Thanks for the links. For us brewers knowledgeable about water, those were quickly easy reads, nothing too surprising. Big take-away was there's a belief that neither zero-mineral water nor uber-mineraled water makes the best coffee -- not at all surprising. But most of us have water in between -- will water with 30 hardness versus 150 have a practical impact on my coffee's taste? Seems highly unlikely. My point above is that if you care enough to go modding your water, you should first determine if your goal is any different from your starting point! I.e. Taste test it yourself.

I've browsed Coffeegeeks here and there but find it, ahem, not for me. Mainly just pseudoscience. Compared to beer brewing, coffee hardly registers as science, for good reason.

This Jim S guy doesn't seem to be much of an expert. His taste test (non-scientific note taking) and recommendation to not bother filtering your tap water hints that he's stuck in the weeds, missing the big picture.

 

Looks to me as if he copied some stuff out of web pages without understanding what he was copying. Saturation index depends greatly on the distribution of hardness between magnesium and calcium as calcium carbonate is much less soluble than magnesium carbonate. Clearly the temperature dependence of SI on temperature must depend on the mix as well as the two salts have different pKs. Etc.

 

Amen to the "ahem". C-geeks is a website full of argumentative posturing. There is some good information* on the web site but it is dispersed throughout a soup of needy personality types. Home-barista is much more knowledgeable and constructive. IMHO the intelligence has been pushed over to that site.

There are many members of this site and the coffee sites who enjoy both coffee and beer (tho not at the same time) but the sciences are very different.

Am I showing my stupidity if I claim that beer brewing is primarily (but not exclusively) microbiology and chemistry while coffee brewing is engineering?
Certainly anyone may show me examples of overlap, but *the emphasis on the coffee sites is about machines, grinders and infusers ("espresso machines") and has to do with the processes that take place in 30 seconds - not in 1 to 40 days as in beer production. The chemistry of the grain, the malt, the yeast is fairly well known while the chemistry of the roasted and the extracted coffee bean is a 'black box' manipulated not by understanding the process (although Scott Rao is trying to make up for this) but by what I must term 'teleological empiricism', or, as you have stated, how it tastes.

Coffee geeks (in the wider sense) are hungry for the application of the scientific method to their craft, but mostly must settle for 'blind tasting', often by representatives with whom they might not necessarily agree.

The recent (within 3-4 years) emphasis on brew water (knowledge of brew water of course goes back to the days of robusta) is not how should it behave or how will it behave given its chemistry. Since water is interacting with a matrix of unknown bean chemistry, we are doing well just to taste-test varying one or two parameters while attempting to hold others constant. This is leading most of us non-chemistry majors into exercises where we need to rely upon Br'un Water.

If either of the Jims, or anyone else, is spreading erroneous information on water chemistry, feel free to join up and post a correction, just as I attempted to do on this thread regarding water and taste.

BT