Just saw (and posted on) an old thread about this, but thought I would start a new one to try to clear up my confusion about using a Quooker with household water softener.
Surely their own limescale filter that they sell is a water softener to all intents and purposes - it's certainly described as doing the same job i.e. by ion exchange.
In which case, why not plumb to feed from household water softener? The only reason for NOT doing this would be wanting hard water for drinking and making hot drinks to avoid slightly high sodium levels (or possibly your individual taste preferences). I can't find anything on Quooker website that describes whether all the water (cold hot and boiling) gets treated by their anti scale accessory tank. Definitely feel like I'm going round in circles with this one.