Jaką wodę ze sklepu polecacie?Moja woda z kranu ...

I would question why your tap water isn't suitable... you drink it, I assume? I would steer clear of RO (or distilled) water (you have to do a lot to add minerals back into it and, imho, that's a pain) .... any Spring water will be good but do check the pH of whatever you get... and remember that Spring water comes from the ground - just as, I presume, your tap water does.... If you could give us the reason you're saying your tap water isn't suitable, that would help! Good luck!

is distilled cheaper than bottled? invest in an RO filter? or, maybe a more basic filter is enough to make your tap useable? The type you'd connect on an RV, for example. Think those are good for 10,000 gallons or so

RO or similar well filtered water is good. I bet any mountain spring water with zero additives is good too.

Any water from 5 to 8 PH I don't know what kind of water u have in your country anyone will do the job but u will still need to do ph down to make it perfect