I know what you're talking about, and I can't understand why MB doesn't have them. They are a really nice safety feature in my opinion, because even the smallest amount of water in the injection pump can really do a lot of damage. My VW Jetta had a whole big water seperator unit under the car, and then a drain valve in the filter itself. I'm quite sure even the newest VW diesels have the same filter. What's up with Mercedes?