Well, there goes another assumption about M-B out the window. A diesel without a water separator is a problem waiting to happen. Even my simple little Datsun diesel pick up had a water separator.
As EdMclass pointed out, the reason why there is no water separator is because one of the SEVERAL fuel filters will catch the water on it's way to the engine.
I have never seen an MB diesel that had problems due to water contamination. Niether has my MB Mechanic.
I don't mean to attack you, but it is apparent that you keep pointing out what appear to be to you "little errors" made by the MB factory. However, the truth is that there is a reason for everything that is on that car. It is a well known fact that these cars are probably the most over-engineered cars on the road. We could argue this all day, but the fact is that more than one of these cars (actualy several) have completed over 1 million miles. Many right here in the USA have completed over 500,000. The fact that there are more of these cars on the road than almost any other from the time period speaks for itself.
Sorry for the rant, but I had to get that off my chest.