Chriss29 - To put in perspective: I’ve been using Distilled water + sodium or potassium bicarbonate with the Elizabeth for almost 3 years. The machine still sounds and behaves as it was new. I never descale, or intend to, for the reason stated above. I have however cleaned and lubricated the steam tap once. There was nothing wrong with it, but thought I’d do some maintenance, also to learn things.
As Jake says, you should be absolutely fine with that water. If the steam disk is leaking, it’s certainly not due to limescale. Putting citric acid through the machine will do absolutely no good at all.