Israel’s Sowillo Energy (see here previously) has developed a system to use energy from the hot water wasted in showering or washing dishes or clothes. Instead of going down the drain, the system redirects the water to a tank where it heats a coil that generates hot water for others in the building.
https://nocamels.com/2024/05/shower-power-making-wasted-hot-water-a-smart-source-of-energy/