I am getting to the second of the 2 water recipes that I want to test for espresso. I started with the rpavlis recipe and now moved to my own with about 50ppm as CaCO3 of hardness as well as alkalinity, split 50:50 between CaCO3 and MgCO3.

The 2 coffees I test are a chocolaty Brazilian by The Visit (not on the website) and a fruity Colombian by Gardelli.

I still need some time to test the 2 coffees, but I had the first espresso with my recipe and it is a night and day difference for the Colombian. I didn't mind the taste of either coffee with the rpavlis water, but the fruity notes of the Colombian are much more present with the added Mg and Ca.

I am also curious if I should taste test a water that is based on only Mg to avoid limescale completely. That would open up the possibility to raise the hardness independent of the alkalinity by adding MgSO4 without the risk of CaCO4 forming. I plan to have an alkalinity of 50ppm as CaCO3 and hardness of 60ppm as CaCO3. The SO4 would be raise by not even 10 ppm with this mix.

The "new" pour over water recipe has some serious deposits after just short usage in my kettle. The deposits can be wiped away easily in a kettle. This will not be possible in a boiler, therefore I would recommend to be careful.

I just swapped the water for the Mg only recipe and the cup seems to be the same.

These tests are really not sufficient yet. A side by side with the same machines would be nice, but I guess will never happen.

I have to test the rPavlis water once more. As my previous findings could be based on confirmation bias

So far I would jump to this conclusion, but as I said it is more of a feeling than a test result. Chocolate flavors are similar with or without the hardness, fruity flavors are enhanced by harder water, no matter if Ca or Mg.

Please let me know about your experiences.

Thanks for this thread. I've been thinking of trying water recipes for pour-over. I'm generally happy with my filtered tap water where I live, but curious if I could achieve better taste and extraction with a water recipe. Do you have any updates on your tests?

For Pour Over I would definitely try to use water recipes at least once.
For Pour Over I think the new recipe is a bit cleaner in the cup somehow.
Visually the water in the kettle as well as my 5 liter bottle is a bit cloudy. With the old water it was not at all cloudy, but there were some tiny bits floating in the kettle starting after the first boil. I don't really mind either, but it is a difference. And I am unsure if I should use similar recipes for espresso, definitely one should not use the same recipes in an espresso machine.

For espresso my plan is to find a recipe with lower hardness than 50, as I think it should be fine for my taste preference. I would prefer to avoid any amount of minerals that do not fully dissolve in the water.
Maybe I even run with the original rpavlis recipe, further testing is needed.