The Mechanism Behind Auto-Flush Toilets

With an automatic toilet, you’ll probably spot a small black circle nearby that looks a bit like a button – it’s an infra-red sensor. This detects body heat, and is connected to an electronic valve inside the water tank.

The sensor is triggered when you wave your hand in front of it or move away from the toilet, and sends a signal to the valve to empty the water from the tank. This flushes the toilet and the tank is then refilled. Electric toilets could be hazardous if the water and electricity mixed, so most are battery powered for safety.