full anti scald protection in the event of a change in water supply temperature fig4 a 4b 4c show an aerator module 312 containing a temperature sensor transmitter 16 a temperature sensor 26 a controller transmitter 28 a user detector 302 a battery 316 and an optional bypass button 24 the user detector 302 can be any touchless detection switch known in the art that is suitable for a faucet application for example the user detector 302 could be an infrared switch the user detector 302 acts to detect the presence of a user generally a user 39 s hands approaching the faucet 12 the aerator module 312 is provided with a bore 32 to permit the passage of water there through and standard faucet threads 34 to permit attachment of the aerator module 312 to the outflow end of faucet the temperature sensor 26 extends into the bore 32 to obtain temperature data from the fluid flowing through the bore 32 the bypass button 24 may be implemented to enable a user to access hotter water than would otherwise be allowed to flow from the faucet essentially in the event that a user wishes to access hotter water pressing the by pass button will prevent the controller 18 shut off valve from closing in the event that the maximum temperature is exceeded during a particular user session the controller transmitter 28 receives and processes signals from.