Can Calypso shut off the Sedna Zigbee Smart Valve
if a water leak is detected from the water heater?

The Zigbee smart valve (VA4220ZB/VA4221ZB) can be shut off if the water detection cable (AC4200C-02) connected to your Calypso Zigbee controller (RM3500ZB) senses a leak from the water heater through a water automation that you will need to create and that will shut off power to the water heater in the event of a leak.