There are water valves/taps that can be controlled remotely using Bluetooth or Wifi... never used one of them, so I can't comment more on it. There are quite so

There are water valves/taps that can be controlled remotely using Bluetooth or Wifi... never used one of them, so I can't comment more on it. There are quite some different brands/models and having different applications (e.g. for gardening, home automation, etc.). You'll probably need a plumber to install one of them ahead of the pipes coming to the bathroom, or replacing an existing tap (often such taps are already existing, e.g. to stop the water in the bathroom for maintenance).