How does water softener affect coffee brews?

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

#1: Post by Ora »

My normal tap water is usually high in calcium so I get limescale buildup in kettles so I have a whole house water softener system to remedy this. It results in that "slippery" water feeling like in showers. I noticed thst brewed coffee made the flavors muted and even getting a better grinder did little to increase flavors. So today I tried brewing with bottled ozarka spring water and the acidity was on a different level than my usual brews and the draw down time was faster with less stalling.

Is the salt from the softener messing with extraction? Would adding minerals like baking soda and Epsom salts resolve some of my issues?

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#2: Post by Peppersass »

The accepted literature on extraction maintains that a certain level of hardness is necessary. I believe this mainly applies to how complete the extraction is, as opposed to which flavor compounds are extracted.

You can find the SCA standards for brewing water here. Note that mg/L (milligrams per Liter) is the same as ppm (parts per million.) Either can be calculated by multiplying the number of grains by 17.

The 68 ppm target for hardness is considered sufficient for extraction but is less likely to form scale, which can be a serious problem for espresso and brewing machines. I would take the pH recommendations with a grain of salt (pun intended.) The low end borders on unacceptably acidic, at least according to some espresso machine manufacturers, and could cause corrosion if you're using an espresso or brewing machine. I'm surprised that alkaline water with reduced hardness isn't acceptable to SCA. Scale formation is also dependent on alkalinity. You can read more about that and the impact of softening on extraction and taste in Jim Schulman's Insanely Long Water FAQ.

The first thing to do is determine the mineral content of the water produced by your whole-house softener. It's possible that it's removing more than just hardness, or the concentration of other minerals, like alkalinity, that remain in your softened water is insufficient for complete extraction. You can test the water with an inexpensive hardness and alkalinity test kit like this one. If you want more accuracy, I recommend the Hach hardness and Hach alkalinity kits, but they're a lot more expensive. You can also get an inexpensive TDS meter like this one.

FWIW, we have well water with about 150-200 ppm of hardness. The TDS is about 150. I use a dedicated cation (salt ion) softener for the espresso machine. It removes 100% of the hardness, but leaves all other mineral content intact. So the output water has salt ions, along with relatively high levels of alkalinity and TDS. I have no problems with extraction. In fact, for a while I used a different softener that removed all mineral content and added back some tap water to produce hardness and alkalinity of about 70 ppm. There was no noticable difference in extraction from the cation softener. I suspect the salt or other minerals left in the water by the cation softener aid extraction. There's nothing in the literature about this.
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#3: Post by homeburrero »

Good advice above from Peppersass. Of course if you're brewing from a kettle limescale is not so much of an issue. Kettles are easy to descale.

That online SCA water standard is the old 'heritage' SCAA standard. The SCA has a newer water quality handbook that allows for more variability, especially with respect to hardness, and is more nuanced - not so easily reduced to a simple table. The new handbook doesn't specify calcium hardness, but does recommend total hardness in the 50 - 175 ppm range and that alkalinity be less than hardness in the 40 - 75 ppm range (CaCO3 equivalents). That still rules out most conventionally softened water from being optimal per the SCA guidelines.

Ora wrote:Is the salt from the softener messing with extraction? Would adding minerals like baking soda and Epsom salts resolve some of my issues?
Hard water typically has high alkalinity along with the high hardness, and your conventional softener removes the hardness (calcium and magnesium ion) but not the alkalinity. In brewed coffee, high alkalinity is associated with dull flat coffee due to buffering of acids by the bicarbonate. It also causes a foamier bloom and a slower draw down (This was reported in the old 2011 SCAA water quality handbook) so your experience with that bottled Ozarka* makes sense.

Of course adding minerals will do nothing to drop your high alkalinity, and I doubt that adding hardness minerals would improve your taste. It may depend on the coffee and on your taste preferences. If you have a tap somewhere (maybe the garden) of unsoftened water you might give that a taste test to see.

There is a hypothesis supported by binding energy calculations that divalent cations (calcium and magnesium) should extract more than the sodium or potassium that you have in their place with softened water. Experiments with refractometers have failed to demonstrate that effect. Some taste tests have indicated that for some coffees and some tasters there might be some benefit to having hardness minerals in the brew water. One logical counterargument (from the late R. Pavlis) to the need for hardness minerals in the brew water is that the liquid percolating through the coffee bed has high concentrations of calcium and especially magnesium that comes from the ground coffee itself, and the relatively small amount that might be in the hardest brew water would be a drop in the bucket.

* Ozarka bottled spring water is from one of three East Texas springs, all of which have extremely low (less than 12 ppm) alkalinity ( ... WAR-EN.pdf)
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