HowStuffWorks: Reverse Osmosis
howstuffworks.com
How does reverse osmosis work to purify or filter the water?
Treatment Systems for Household Water Supplies - Activated Carbon Filtration
ext.nodak.edu
1992 article from the North Dakota State University Extension Service explaining in detail what activated charcoal systems can and cannot do.
Home Water Treatment Using Activated Carbon
msue.msu.edu
Discussion and guidelines from a 1997 article from the Michigan State University Extension.
HowStuffWorks: Charcoal Filters
howstuffworks.com
What is activated charcoal and why is it used in filters?