I did find these, though...regarding using grapefruit seed extract and Hydrogen Peroxide and other products...
http://www.ehow.com/how_6962639_purify-water-grapefruit-seed-extract.html
http://inspectapedia.com/water/Drinking_Water_Purification5.htm
IMO its handy to have this information available but its not my primary plan. I have multiple ways to purify drinking water. First is a simple 3 stage home built filter. It uses sand, DE powder, and charcoal to filter contaminates out of water. Then I plan to put the water through my berky and finally will probably add a little of the chlorine solution depending on the original source.
If its rain water I’ll probably only do the 3 stage filter. I also have a backpacking pump filter which does a pretty good job.
Bad water kills lots of people every year, not in the USA currently but in less developed countries. IF TSHTF here I can guarantee that many sources of surface water will quickly be contaminated with garbage, sewage, and perhaps bodies. There are some really nasty diseases spread through the water. Even if it only makes you sick it would reduce your strength and ability to cope with a myriad of other problems.
Oh and I agree vinegar has many excellent uses for cleaning and disinfecting.