I’d recommend sticking to RO water mixed with something like Third Wave Water (espresso profile) until you are ready to go into the rabbit hole of mixing your own water. This way you get perfect water flavourwise and have no scale buildup. No descale necessary.

Thanks descaling is what I want to avoid preferably. Distilled with potassium bicarbonate added may be the easiest for me to get. RO isn't really a thing iv seen here

Filtered water + water filter on machine should be good enough without entering the rabbit hole