fuel pump & filter built in one unit submerged in the fuel tank....external fuel filter "is" fitted to some cars in certain countries
not sure if the fuel tank is anti-syphon
if you really think its contaminated fuel then drain the tank but as already said dont over look the obvious...
clear the fault codes and drive it again to see what comes back as not all those maybe "new"
then as already said basics first.....but could be the lambda sensor issue causing wrong fuelling....