Yes, the idea behind the rpavlis water is that it has nothing (no chloride, sulfate, etc.) that might cause corrosion, and nothing (calcium, magnesium, silica, etc.) that might cause scale or similar deposits. And has good alkalinity for corrosion protection but not so much that it might dull the acidity/brightness of an espresso. And if you use potassium bicarbonate you aren't adding any sodium at all. Since coffee is already loaded with potassium the relatively tiny amount of potassium in the water should have no affect on taste. So it's a recipe for ideal machine health but also tweaked for good taste.sbenyo wrote:If taste is not an issue, is the rpavlis completely safe to the machine and is the recommended formula?
There are people who believe that you need hardness minerals (calcium and/or magnesium) for optimal taste. Extraction and taste experiments have not clearly demonstrated to what extent that might be true, and it probably depends on the coffee being brewed. The Jayarr Coffee recipe above would give you water with magnesium hardness of 80 mg/L CaCO3 equivalent, alkalinity of 40 mg/L CaCO3 equivalent, and sulfate ion of 77 mg/L. (To see that in context of other waters' hardness/alkalinity you can refer to this chart.) It's advised for brewed coffee, but you could probably use it in an espresso machine without scaling issues because it has no calcium at all.sbenyo wrote:Is there any advantage using a formula that has both alkalinity/buffer and hardness (Mg)? Something like this:
https://jayarrcoffee.com/blogs/news/a-g ... king-soda/
Lots of folks who make water using these minerals - Epsom salt and sodium bicarbonate, use the Barista Hustle two-bottle concentrates: https://www.baristahustle.com/blog/diy- ... pes-redux/ . Barista Hustle recipe 4 is the same as that Jayarr Coffee recipe.