What's a good ppm alkalinity level for coffee brewing water?

[Silver_Is_Money]

What level of alkalinity is considered ideal for coffee brewing? I was initially thinking of 50 ppm alkalinity (which is the same as 61 ppm of bicarbonate). Your thoughts?

 

[Robert65]

Purely anecdotally, my city tap water averages about 77ppm total alkalinity, 35 ppm Ca, 40ppm Na, and 50ppm each Cl and SO4. Carbon filtered, I think it makes darn good coffee, such that amending or substituting it has never crossed my mind.

 

[Silver_Is_Money]

Purely anecdotally, my city tap water averages about 77ppm total alkalinity, 35 ppm Ca, 40ppm Na, and 50ppm each Cl and SO4. Carbon filtered, I think it makes darn good coffee, such that amending or substituting it has never crossed my mind.

Nice! What is your magnesium level?

 

[Robert65]

I've never seen it shown on the city water report. I have to infer it based on hardness (avg. 109ppm) to be about 10ppm.

 

[Unicorn_Platypus]

I was wondering the same thing. If harder water is better for stout to balance acidity from roasted grains. Wouldn't the same also be true for brewing a smooth cup of coffee?

 

[Robert65]

I think a little alkalinity would balance the acid. Just intuitively. Don't know how hardness (Ca and Mg) fits in, don't really know the science of coffee. I remember Alton Brown suggesting a pinch of salt would counter bitterness, so maybe some sodium helps? Or chloride, the way it gives beer a rounder, fuller character?

 

[Silver_Is_Money]

I've never seen it shown on the city water report. I have to infer it based on hardness (avg. 109ppm) to be about 10ppm.

If your total hardness is 109 ppm and your calcium is 40 ppm, your magnesium is 2.2 ppm.

 

[Silver_Is_Money]

I found an organization called the "Specialty Coffee Association", and they claim to have researched this and come up with the following as the ideal targets for coffee water:

https://sca.coffee/research/coffee-standards?page=resources&d=water-standards

 

[Hanglow]

I've wondered this too, mainly thinking that lower alkalinity would be better ( at least compared to high alkalinity) as you'd extract less tannins.

 

[mongoose33]

I have a Keurig in my office, and I bring in jugs of RO water to feed it. That RO water is about 5-6 ppm of dissolved solids.

I use Pikes Place coffee k-cups (Starbucks). I used to buy that coffee from the shop on campus, eventually when I got the Keurig realized I saved about $1/cup with it. Far as I can tell, it tastes pretty much the same whether I use my RO water or get coffee from the shop, where they're using local tap water (which is very alkaline).

I guess the answer to the question is, what tastes best to you?

 

[Silver_Is_Money]

I've had coffee made with extremely high alkalinity (and likely high everything else) well water, and it is like drinking mud water.

As opposed to that, strong black coffee made with RO water tastes acrid and acidic to me.

But if given only these two extremes as choices, I'll take the coffee brewed in RO water every time.

 

[Silver_Is_Money]

Keeping it simple to remember, for 5 gallons of coffee water starting life as high quality RO or distilled, an addition of 1-1/4 grams each of Gypsum, Calcium Chloride (dihydrate*), Epsom Salt, and Baking Soda seems to hit all of the right buttons.

And if you have one of those 4 gallon water containers for RO, all of the same mineral additions are exactly 1 gram.

*If your calcium chloride is anhydrous (as opposed to the dihydrate state), add 1 gram in 5 gallons, or 3/4 gram in 4 gallons.

*** A few websites I came across on this subject suggested oddly enough that high magnesium sulfate water is good for coffee (as opposed to beer), and those sites suggested Epsom Salt and Baking Soda as the only requisite mineral additions.***

 

[mabrungard]

I’m skeptical that magnesium and sulfate would be helpful in coffee water. I definitely agree that some alkalinity and chloride would be good.

 

[Silver_Is_Money]

I’m skeptical that magnesium and sulfate would be helpful in coffee water. I definitely agree that some alkalinity and chloride would be good.

Agreed! I wasn't buying the magnesium overload either.

 

[Hanglow]

I wonder if tea has a similar water that works, I know I much prefer tea made with soft water over hard.

 

[mabrungard]

I find that minimal alkalinity is good for tea. The tannins are harsher with more alkalinity.

 

[ScrewyBrewer]

I've been using pure reverse osmosis water for making coffee. I like the way it tastes when brewing coffees like Green Mountain, Wegmans, QuickChek, Dunkin Donuts and other brands.

 

[Silver_Is_Money]

I've been using pure reverse osmosis water for making coffee. I like the way it tastes when brewing coffees like Green Mountain, Wegmans, QuickChek, Dunkin Donuts and other brands.

That's what I'm currently using also. But I'd like to explore adding some minerals and alkalinity to see if in fact it noticeably improves the coffee(s). I'm going to whip up 4 gallons as per post #12 above.

 

[Silver_Is_Money]

I made up some mineral water for coffee from 4 gallons of 'Clearwater Systems' brand RO that tested at 6 ppm TDS (per Clearwater). I added:

1.3 g Baking Soda
1.0 g Epsom Salt
1.0 g Gypsum
1.0 g Calcium Chloride

This morning I'm sipping on my first cup of black coffee brewed with this water. Formerly I had been using straight RO for years.

The immediate difference I notice in the taste is that much of the acrid acid bite is gone. I'm so used to this bite at this juncture that I'm sort of missing it. But it does allow for a lot of other flavors within the coffee to shine. Any change to coffee (such as brand or type of bean) throws me off a bit for a couple pots, and this change is right in line. Guess I'll have to drink a few pots before making my final decision.

Edit: My wife (who regularly drinks her cups of coffee with 1 TBSP of added heavy whipping cream) just announced that she doesn't like the taste of the coffee brewed in the mineral modified RO water at all when cream is added to it. But she likes it black a lot more than she liked our standard RO coffee black. She said she may have to switch to black coffee if I insist on continuing this experiment.

 

[Silver_Is_Money]

I just tried a cup with the heavy whipping cream added and it's fantastic. But 60-70 extra calories per cup, plus the added cost, are not what I need.

 

[aeviaanah]

I made up some mineral water for coffee from 4 gallons of 'Clearwater Systems' brand RO that tested at 6 ppm TDS (per Clearwater). I added:

1.3 g Baking Soda
1.0 g Epsom Salt
1.0 g Gypsum
1.0 g Calcium Chloride

This morning I'm sipping on my first cup of black coffee brewed with this water. Formerly I had been using straight RO for years.

The immediate difference I notice in the taste is that much of the acrid acid bite is gone. I'm so used to this bite at this juncture that I'm sort of missing it. But it does allow for a lot of other flavors within the coffee to shine. Any change to coffee (such as brand or type of bean) throws me off a bit for a couple pots, and this change is right in line. Guess I'll have to drink a few pots before making my final decision.

Edit: My wife (who regularly drinks her cups of coffee with 1 TBSP of added heavy whipping cream) just announced that she doesn't like the taste of the coffee brewed in the mineral modified RO water at all when cream is added to it. But she likes it black a lot more than she liked our standard RO coffee black. She said she may have to switch to black coffee if I insist on continuing this experiment.

I’ve always wondered about water profiles for coffee. I too have ran RO for years preboiled, cooled with a splash of tap then to a French press. From what I understand temperature and time are also critical variables to brewing coffee. I boil in an erlenmyer and splash with the tap- the thought here is is get a bit of minerals and also cool closer to the range coffee should be (if I recall 170-180F?) I don’t feel like measuring temp every morning so this has worked for me.

I’m definitely going to try the water profile you suggest.

 

[Silver_Is_Money]

If I could use only one word to describe the nature of the flavor improvement it would be 'chocolate'.

 

[mabrungard]

This is the same effect as ‘Dutching’ chocolate. The slightly higher pH does the same thing, reduces acridity and deepens the flavors.

 

[Silver_Is_Money]

I finally got around to sampling a cup each of the same black coffee brewed in straight RO water, and brewed in RO with minerals added as per post #19 above, but otherwise brewed identically as to weight of coffee and volume of water. I even went as far as assuring that they were both at the same temperature as I sipped them. The mineralized and alkalized brew had a very nice chocolaty coffee flavor, and by comparison the straight RO coffee was flat and dull sans for a nasty acidity. It was almost like drinking a premium cup of Arabica coffee vs. drinking Robusta bean coffee.

 

[Silver_Is_Money]

I wonder if the calcium, magnesium, chloride, and sulfate bearing minerals are actively contributing to the flavor, or if primarily to exclusively the adding of alkalinity via the baking soda is making for the easily noticeable flavor difference.

 

[Robert65]

I wonder if the calcium, magnesium, chloride, and sulfate bearing minerals are actively contributing to the flavor, or if primarily to exclusively the adding of alkalinity via the baking soda is making for the easily noticeable flavor difference.

Next experiment: same alkalinity, pickling lime vs. baking soda, no other mineralization?

 

[Silver_Is_Money]

Next experiment: same alkalinity, pickling lime vs. baking soda, no other mineralization?

As in baking soda grams x 0.44 = Pickling Lime grams? (1.3 g. baking soda x 0.44 = 0.57 g. of Ca(OH)2)

Pickling lime does introduce hardness in the form of calcium ions. And baking soda introduces sodium ions.

Other differences include the alkalizing ions being bicarbonate vs. hydroxyl (and thereby the pH being noticeably higher for the case of the pickling lime water).

 

[Robert65]

As in baking soda grams x 0.44 = Pickling Lime grams? (1.3 g. baking soda x 0.44 = 0.57 g. of Ca(OH)2)

Pickling lime does introduce hardness in the form of calcium ions. And baking soda introduces sodium ions.

Other differences include the alkalizing ions being bicarbonate vs. hydroxyl (and thereby the pH being noticeably higher for the case of the pickling lime water).

I'm just thinking that if you added the same amount of total alkalinity to two RO waters (I'm pretty sure we can ignore the concept of RA here,) alkalinity would be effectively eliminated as a variable. You could see if the coffees both had the nice, chocolatey character, which might confirm that it results from alkalinity*, and whether you detected any difference, positive or negative, that could then be attributable to the hardness/cations. A way of sorting out what's doing what. Then if the cations do make a difference, it would be possible to play with them, and other elements like sulfate and chloride, as long as alkalinity was kept constant at a level you find desirable. Any way you slice it, you'll be well caffeinated by the time you figure this out!

* I expect they will. As Martin noted this is likely the same effect as in "Dutch process" chocolate.

 

[Silver_Is_Money]

By my calculation, adding 0.57 grams of Ca(OH)2 to 4 gallons of water results in a pH of 11.01. That sort of scares me.

MW of Ca(OH)2 = 74 g/mol

0.57 g/74 g/mol = 0.0077 moles of Ca(OH)2

But two OH- are liberated from each Ca(OH)2 molecule, so the moles of released OH- = 2*0.0077 = 0.0154 moles

4 gallons = 15.1416 Liters

0.0154 moles / 15.1416 Liters = 0.00102 molar OH- concentration

-Log(0.00102) = 2.99 pOH

14 - 2.99 = 11.01 pH

Of course this would only be the pH for fully dissociated Ca(OH)2. The actual pH will be less. Still learning here. Any help in solving for the actual pH is well appreciated.

 

[Silver_Is_Money]

OK, this might be better (???):

pH = pKa + log(molar concentration)

pKa1 for Ca(OH)2 = 11.57

log(0.00102) = -2.99

pH = 11.57 + -2.99 = 8.58 (which is nowhere near as scary as pH 11.01)

But then there is also pKa2 = 12.63... Hmmmm????

 

[Silver_Is_Money]

For 1.3 grams of baking soda added to 4 gallons of RO the pH computes to:

MW of NaHCO3 = 84.0066 g/mol

1.3 g/84.0066 g/mol = 0.015475 moles of NaHCO3

4 gallons = 15.1416 Liters

0.015475 moles / 15.1416 Liters = 0.001022 molar HCO3- concentration

Log(0.001022) = -2.9905

pKa = 10.329

pH = 10.329 + -2.9905 = 7.34

Edited to correct the molecular weight of baking soda.

 

[Silver_Is_Money]

I made a batch of coffee using water from our under the sink RO unit and a batch with the same RO water plus baking soda adding ~51 ppm of additional alkalinity. No other minerals added. Drinking them side by side at the same temperature I'm noticing little to no discernible flavor differences between them sans for slightly less acid bite for the batch that received the baking soda. If anything, acid reduction alone (plus some added sodium) is actually making the baking soda coffee ever so slightly less flavorful and more dull tasting than the straight RO coffee. This was highly unexpected. To my pallet none of the rich chocolate like flavors I received from the baking soda plus other minerals coffee are derived from the addition of baking soda alone.

The difference in make-up was 2.2 Liters of RO plus 0.19 grams of added baking soda vs. 2.2 Liters of RO only.

 

[Silver_Is_Money]

In all honesty I'm barely discerning the acidity difference, and if this had been done as a blind taste test I may well have failed to pick the odd coffee out.

 

[Robert65]

Well, it seems you're approaching a general truth, that "natural" waters make better coffee than deionized water. Which is more or less conventional wisdom, WRT coffee, tea, baking, and cooking in general. A moderate level of many minerals will probably be beneficial, but specifics may not be terribly critical, as long as the water itself is palatable -- which some well water isn't. (In fact deionized water doesn't even make good tasting drinking water, IMO.) My hypothesis.

 

[Silver_Is_Money]

OK, this might be better (???):

pH = pKa + log(molar concentration)

pKa1 for Ca(OH)2 = 11.57

log(0.00102) = -2.99

pH = 11.57 + -2.99 = 8.58 (which is nowhere near as scary as pH 11.01)

But then there is also pKa2 = 12.63... Hmmmm????

I'm still thinking about this pH determination matter (where is AJ when I need him?).

pKa1 (11.57) is strictly associated with the release of the first of two OH- ions from the Ca(OH)2, and pKa2 (12.63) is strictly associated with the release of the second of the two OH- ions. Therefore if the molar concentration of OH- is 0.00102 for the case of both ions being liberated, it is half of that for each individual OH- ion, or 0.00102/2 = 0.00051 molar.

For the first OH- ion release we get:
log(0.00051) = -3.292
pH = 11.57 + -3.292 = 8.278 pH

For the second OH- ion release we get:
log(0.00051) = -3.292
pH = 12.63 + -3.292 = 9.338 pH

The upper limit for the pH is 9.34, and the lower limit for the pH is 8.28, and the reality is likely to fall somewhere between these two extremes (presuming of course that this general method is even related to the correct method to begin with, which it may well not be). Their average comes to 8.81 pH, but somehow I doubt that averaging is how the correct answer is to be calculated. Calling @ajdelange for assistance here. And also welcoming anyone else who can show how this pH is properly to be calculated.

 

[Silver_Is_Money]

Of course I could just go out and get 4 gallons of Clearwater Systems RO water and add 0.57 grams of pickling lime to it, stir well, and then take the pH reading of it with my new (and still not yet out of the box) pH meter. That might tell me something.

I can't use my under the sink RO unit for such precision science, because my RO's TDS is well above the typical TDS of Clearwater Systems RO.

 

[mabrungard]

Well, it seems you're approaching a general truth, that "natural" waters make better coffee than deionized water.

That’s a generalization that only a few water sources can claim. Many sources have too much alkalinity and that’s a detriment to many beverages.

 

[Robert65]

That’s a generalization that only a few water sources can claim. Many sources have too much alkalinity and that’s a detriment to many beverages.

By natural I just meant mineralized, that some minerals are necessary, as opposed to deionized. That probably also applies to most beverages. I should have worded it differently.

 

[Silver_Is_Money]

New morning, new test. This time I've mineralized 4 gallons of our under the sink RO with 1 gram each of CaCl2, CaSO4, MgSO4, and baking soda. By cutting the baking soda from 1.3 grams to 1.0 grams I'm attempting to compensate for the alkalinity present within our homes mediocre RO water vs. high quality Clearwater Systems RO water.

I'm presently sipping on coffee brewed with straight RO water from my under-sink RO unit, while also sipping on coffee made from the above described mineralized RO water. The brews were made as equally otherwise as I could make them.

The bottom line is that the mineralized under-sink RO water coffee has most (but not quite all) of the delicious rich chocolate character that I remember from the earlier premium quality Clearwater RO with minerals coffee, and the straight RO batch tastes flat, dull, and empty by comparison. It basically tastes "watery" or "weak", as if it needs perhaps 20% to 25% (as a first guess) more beans. But I know that I weighed both 12 cup coffee pots beans out to be the same to within a fraction of a gram.

The only difference I note is that since our home RO unit starts out with what I'm presuming to be ~20 ppm alkalinity, I'm not detecting any of the acrid acidity of the straight Clearwater RO based coffee, the source for which which has almost zero alkalinity. Apparently around 20 ppm alkalinity is totally sufficient to alleviate the acidity issue. But with no chocolate qualities, and also no acrid/acid qualities, the home RO unit sourced coffee has literally no character going for it and thereby "hopelessly weak" is all that can be said for it. It is the worst coffee of all. And it is also what my wife and I normally drink.

I'm now thinking that I didn't go quite far enough in cutting the added alkalinity of my under-sink RO water, and that for this water about 1/2 to 3/4 gram of baking soda added to 4 gallons of our RO should be plenty. It may even be that it doesn't need baking soda to boost its alkalinity at all, since I'm not detecting acidity in the coffee made from it.

I should state that our under-sink RO unit is being fed from 377 ppm alkalinity (softened) well water, and that is why I initially presume that it has somewhere around 20 ppm (or more, could it be 25-30 or higher ppm?) of alkalinity.

 

[aeviaanah]

New morning, new test. This time I've mineralized 4 gallons of our under the sink RO with 1 gram each of CaCl2, CaSO4, MgSO4, and baking soda. By cutting the baking soda from 1.3 grams to 1.0 grams I'm attempting to compensate for the alkalinity present within our homes mediocre RO water vs. high quality Clearwater Systems RO water.

I'm presently sipping on coffee brewed with straight RO water from my under-sink RO unit, while also sipping on coffee made from the above described mineralized RO water. The brews were made as equally otherwise as I could make them.

The bottom line is that the mineralized under-sink RO water coffee has most (but not quite all) of the delicious rich chocolate character that I remember from the earlier premium quality Clearwater RO with minerals coffee, and the straight RO batch tastes flat, dull, and empty by comparison. It basically tastes "watery" or "weak", as if it needs perhaps 20% to 25% (as a first guess) more beans. But I know that I weighed both 12 cup coffee pots beans out to be the same to within a fraction of a gram.

The only difference I note is that since our home RO unit starts out with what I'm presuming to be ~20 ppm alkalinity, I'm not detecting any of the acrid acidity of the straight Clearwater RO based coffee, the source for which which has almost zero alkalinity. Apparently around 20 ppm alkalinity is totally sufficient to alleviate the acidity issue. But with no chocolate qualities, and also no acrid/acid qualities, the home RO unit sourced coffee has literally no character going for it and thereby "hopelessly weak" is all that can be said for it. It is the worst coffee of all. And it is also what my wife and I normally drink.

I'm now thinking that I didn't go quite far enough in cutting the added alkalinity of my under-sink RO water, and that for this water about 1/2 to 3/4 gram of baking soda added to 4 gallons of our RO should be plenty. It may even be that it doesn't need baking soda to boost its alkalinity at all, since I'm not detecting acidity in the coffee made from it.

I should state that our under-sink RO unit is being fed from 377 ppm alkalinity (softened) well water, and that is why I initially presume that it has somewhere around 20 ppm (or more, could it be 25-30 or higher ppm?) of alkalinity.

Can you post grams per gallon of minerals for treated water? I’d like to check if I get similar results. I get 4ppm out of my RO