Lots of initial fiddling, and learning the how’s and why’s certain filtration/purification elements are involved, but once set up, the output is HIGHLY consistent. So much more than my tap input, which is subject to either shallow or deepwell supplies selected by my water district and varying solute concentrations as the ‘water season’ supplies progresses. Towards the end of summer, most locals simply can no longer drink from the tap. At 90% efficiency, time for filters, badabing…consistency. An EPA ‘Superfund’ site (herbicide factory dumping for over 30 years) less than a mile away got my ball rolling back in the day. I was more focused on ‘purification’ (OP’s title) than taste, but I think RO is an excellent STARTING POINT (not a magic bullet) if the hardness and pH of supply is in range…simply adjust final stage, either by cartridge of manually. Yes, one can still get there by buying distilled and doing the work…and if the hardness and pH of supply are not conducive to RO, then perhaps a home distiller would be a simple and reliable solution. 