homeburrero wrote:Yes. If you go with 2 tablespoons (30 ml) of that concentrate in a gallon of distilled you're at the 1 mmol/L potassium bicarb water that was oft recommended by Dr Pavlis. (Total alkalinity of 50 mg/L as CaCO3 and zero hardness.) He said he would sometimes use only half that amount of bicarbonate for taste reasons when brewing dark roasts.

when making the distilled version, some recipes such as barista hustles website also put epsom salt as well. Is there a need to do this?

The conventional wisdom* is that you need hardness minerals (calcium and/or magnesium) for good coffee, and epsom salt (magnesium sulfate heptahydrate) is an easy way to get that. It's readily available, dissolves easily, and should not normally cause any limescale concerns.

You can always try it and see if you taste an improvement. Don't put it in with your bicarbonate concentrate though. Get another 750ml stoppered bottle of pure water, then put 12 grams of Epsom salt in that and shake well. Then add 1 or 2 tablespoons of that to each gallon of brew water along with the 1 or 2 tablespoons of your bicarb concentrate. 1 tablespoon would put your water at 51 mg/L of hardness as CaCO3 (and also about 49 mg/L of sulfate ion.)


* The rpavlis water bucks that conventional wisdom in having zero hardness. But nevertheless a lot of people use it and find that it makes perfectly tasty coffee. To see some recommended zones and waters on the hardness and alkalinity scale you can check out this post: Good references on water treatment for coffee/espresso