There are many things you can do in the smart home to reduce your water usage and the energy usage required to heat water. You can read my research on this.
Hot water is covered on separate page.
Here in Suffolk, the water is really hard. In out new home we would install a water softener and ideally one that would link to our contextual smart home to let us know when any maintenance is required.
I currently have a number of projects in this space too.
The plan is to use harvested rainwater for flushing toilets, washing machine and smart irrigation.
I also plan to install plumbing to collect grey water from the main bathroom, for filtration and irrigation.