depending on how much water you need something like this may work; https://nl.aliexpress.com/item/10050028 ... 0991%21sea

I'm using one (version with PID) for about 6 months now, adding some KHCO3 and MgSo4 and done.

This is so sad.

Preparing water slowly gets more complicated than making coffee with it.
Espresso is now being demoted to just a minor seasoning...

Not if you make nice ristretto's

old_bear wrote:This is so sad.

Preparing water slowly gets more complicated than making coffee with it.

Since you have a reservoir machine, and since you have taste preferences that may be related to too much or too little GH or KH, I think you should explore making recipe water with purified water and mineral salts. You will need a convenient source for purified, and that might be a countertop distiller or RO, or bottled purified water, or de-ionized from a refill station - whatever is available or convenient. For purified water I use de-ionized water from my grocery backed up by a ZeroWater pitcher for when I suddenly run out -- that is inexpensive, low waste, and convenient for my situation.

Then you can experiment a little to find a level of hardness and alkalinity that is safe for the machine and that also tastes good. The approach in the latest Barista Hustle recipes is pretty easy -- you make two concentrate bottles, one for bicarbonate alkalinity and another for magnesium hardness and can taste test different amounts of each:

For use in the espresso machine you want to keep the alkalinity (BH calls it Buffer) at 40 mg/L and higher, and probably want to steer clear of the extremely hard recipes. For Pourover you can try any of them, but keep in mind that espresso taste is much more tolerant of high alkalinity than is pourover. Once you decide on a recipe you like, making this water routinely at home should be very easy. If you're like many people, you may even find that you don't need any magnesium in the water. Many folks on this site prefer 'rpavlis' water, which is simply 1 millimolar bicarbonate -- for, say, a 15 liter container you would add 1.5 grams of potassium bicarbonate or 1.3 grams of sodium bicarbonate (baking soda).

Yeah, I read and heard a lot about that. And I think it is extremely important to research all of them recipes, to find what's needed. I think it is a fantastic job done for the industry.
But that is just too inconvenient, just no way for daily use. In the end, it must come from a pipe. But opening a valve.
Perhaps, some experiments would be good - I just took SCAE numbers as a reference for now.

And then again, I have just realised that something is going totally wrong. With GH/KH as 7/6, I should have much higher electric conductivity than I measure (22ish mS/m). I should be getting around 195 ppm, hence 30 mS/m, and that if no other ions are present.
Will have to reconfirm all values.

in my experience making the recipe is stupidly simple and it avoids all scale, add MgSo4 to taste or not for espresso... descaling is more work!