Well in all the years I have been testing machines, often with RO water of 2 or 3 TDS, I have never had a fill sensor not work. It’s a bit of an Urban myth that goes round.
Remember that guy with the Minima was overfilling, and I said don’t ground on the boiler, ground on the frame…because just the weak electrical interference can interfere with them. They are super sensitive.
Ultrapure water to special laboratory conditions e.g. 18.2 M Ohm resistance “might” not work…but RO water definitely will, as will distilled. Especially as it becomes more conductive by the second when you fill the tank.
