Hi
Beneath is a water quality rapport from where I live. If you have insight into best water for espresso please comment. Thanks.
It's in Danish btw.

Converting those numbers to conventional units of CaCO3 equivalents you have:
Total hardness: 137 mg/L
Calcium hardness: 122 mg/L
Bicarbonate alkalinity: 99 mg/L

The total alkalinity here would be the same as the bicarbonate alkalinity. It would certainly be scale prone if you don't soften the water.

You also have borderline high chloride ion at 33 mg/L. That's a little above what some espresso machine manufacturers recommend, and you can't easily reduce that without going to a reverse osmosis (RO) treatment system. RO with a blending valve would work great here, or a less expensive RO with a remineralization cartridge would do.

If you have a vintage or very expensive machine that you want to pass on to your grandkids, you probably do want to be very conservative about removing that chloride with an RO system. Otherwise, my opinion is that you could do fine here with just a filtration system that removes chlorine and particulates with a carbon or charcoal filter, and that also softens the water with a conventional softener -- i.e., one that uses a strong acid cation (SAC) cation exchange resin to replace calcium and magnesium with sodium (or sometimes potassium) ions. These are widely available and have been used for decades, including as whole house softening solutions. The advantage of this over one of the newer decarbonizing softener (a weak acid cation (WAC) softener that replaces calcium and magnesium with H+ ions) is that it will not reduce your alkalinity or acidify the water. That alkalinity is good to have when you have that potentially corrosive chloride.

Of course, you also have the option of using bottled or recipe water instead of trying to treat this water.

P.S. Filters like the BWT bestmax, the Everpure Claris, the Mavea Quell ST are all examples of decarbonizing filters. They generally have adjustable bypass heads. They are effective in reducing scale because they reduce the hardness, reduce the alkalinity, and reduce the pH, all three of which help to reduce limescale. But they may not be a good choice where you have low alkalinity or where you have high chloride ion.

Thank you so much for taking time to give me a thorough explanation. It's very much appreciated.

I have a water distiller coming next week. I plan on using Third Wave Water at first and then later maybe mixing my own minerals.

Doing this, do I have to use a filter?( I have a Lelit Bianca and use their resin filter).

Thanks:)

Kokoro wrote:I have a water distiller coming next week. I plan on using Third Wave Water at first and then later maybe mixing my own minerals.
Doing this, do I have to use a filter?( I have a Lelit Bianca and use their resin filter).

If mixing your own from distilled or otherwise purified then you don't need nor want that LeLit filter. You can add a simple hose end screen filter (If you don't already have one) that just prevents any particles that may have gotten into the reservoir from being sucked in the intake.

Great. Thanks. It's already in the water tank on the lelit bianca.