In many countries it is customary to have a bidet spray inside the bowl of the toilet, which is operated by an on/off isolator valve located conveniently to hand on the wall.
Having the bidet spray nozzle located within the toilet bowl, has a number of benefits:-
Keeps water inside the bowl, thus reduces water splashing on the floor which can be both unpleasant for other users and a potential slip hazzard.
Inbuilt nozzle is more reliable than a handheld spray the inbuilt nozzle cannot be stolen.
Back Flow Preventer
In some countries including the UK, building regulations exist which stipulate that a back-flow preventer is installed in line to the bidet nozzle, to avoid the possibility of germs flowing back to the main water supply.
WuduMate Order Code - WuduMate TT BFP
Spec Sheet: Toilet with Bidet Spray (Turkish Toilet).pdf