Ernie1 backflushing once every day is presumably at least half a litre of water that’s effectively wasted.
This is so true. I remember when I had my E61 and remember thinking… oh well, perfectly fine water simply wasted. Not an issue with the Elizabeth, as that’s not necessary - not to that extent at least.
But remember that, at the time, Zero Water jugs, or Osmio Zero or even distillers were not a common thing. For instance, if I were to switch to a machine which is not economical with water, like an E61 group, or a lever group, I’d definitely look at moving away from bottled water, or distilled water, or find a routine which works for you which minimises wastage.