As many are probably already aware, there are a number of fuel-filter type products available which are specifically designed to remove physical impurities from fuel.
However, for those who are concerned with fuel purity more generally and especially those running duel fuel pumps involving F/I setups (e.g., GT40s or GT500s) where fuel purity is essential, the standard fuel filter may not provide protection against another common source of fuel contamination: water.
Fortunately, there are a number of manufacturers who make such products, including Perma-Cool, whose products are "universal fits" and can be purchased relatively inexpensively, e.g., at JEGS and JC Whitney:
Perma-Cool 81794 - Perma-Cool Fuel Filter/Water Separator Kits - JEGS http://www.jcwhitney.com/autoparts/P...fuel+separator
FYI: fuel delivery/purity, especially for duel fuel pumps 
