We use two types of treatment.
The cold water tap to the kitchen sink is unfiltered and untreated. We use that water for cooking and washing up.
Then we have a reverse osmosis filter that has its own tap next to the kitchen sink. We use that water for drinking and watering the carnivorous plants.
The water for the rest of the house goes through one of
these. It doesn't remove the scale, it just stops it getting hard by binding a phosphor salt ion to the calcium. It's also pretty good as removing hard scale from systems.
We use this water for showering, hand washing, teeth cleaning, filling the washing machine etc.
Hope this helps