Define this...

[Borast]

I define "running water" as just that. Water with an actual current.

Salt water or Fresh, doesn't matter.

Even polluted water, if the vamp falls into a polluted stream, he's still toast. However, me can freely cross most swamps and fens.

The other way I describe it is as "living" water, swamps and fens tend to be "dead" water, or stagnant.

[RoadWarriorFWaNK]

if you water your plants with nothing but soda or sewage, they will probably die very quickly. YOu know why? Because they need fresh water to survive. common sense (as much as it applies to an RPG) would tell you that the same holds true for killing vampires.

[Svartalf]

Borast more or less summarizes my position :

water must be moving with a distinct flow (whether it's a stream or a squirt gun) ... still water (like a lake or pond) does not hurt them so much, and cannot destroy them utterly, and they actually immune (as well as not fearful of) stagnant water (such as a swamp or fen) ... similarly, the "water" in a fog is still... when there is wind to move it, the fog disappears.

Polluted water, salt water, fizzy water are still water... to an extent : if the water would be toxic to a human... it's no longer so to a vamp.
Conversely, liquids that are water rich, but not water, say, soda or urine, do no more than P the vamp O