Yes, it will behave like a shower head filter for hard water.
Because the T56 is treating all of the water coming into your home, your shower water also be treated. You’ll see less scale build-up on your shower head, taps, bath, and within your shower cubicle.
It’s works in a similar way to a traditional shower water softener, so you’ll also find it easier to form a lather from soap and your shampoo will be more effective.