Science [& some potheads on the internet] say no, it does not filter tar. Here's why:
Tar=Benzopyrene
http://en.wikipedia.org/wiki/Benzopyrene
Benzopyrene has a solubility in water of 0.00000038 g/100 mL (taken from
http://www.iephb.nw.ru/~spirov/hazar...)_pyrene.html), or 0.0038 mg/L.
It's practically insoluble.
http://forum.grasscity.com/recreatio...fficiency.html
The water DOES get dirty because it filters out PARTICULATE matter.