I'm probally giving away way too much info but...
Most Bacteria are under 10 micron, usually 3 microns in size or as small as 0.3 micron. Viruses go as small as .03 micron in size.
Radiactive dirt in water would be usually in the 1 - 50 micron size.
Coffee filters have pores as large as 100 microns.
The usual limit of human eyesite is 50 microns.
A single cofee filter will not stop anything you want it to. You can layer them but again it will work better but still not perfect.
A research project done on 3rd world water filtration a few years ago looked at using 7 layers of fine silk and it removed 95% of the various water
born problems.
If you can fint one the really fine wine filters (disk and a special holder) can take out stuff to 1 micron. Also those house filters that you get at
Home depot and other places work very well.. but the filters they sell only go down to 10-20 micron. There is a company called Osmonics that sells
filters for those housings that go as low as 0.03 micron (water for hospitals) but I havn't had any dealings with them since they were bought out by
GE a while ago.
Lastly I started a thread a few days ago about defeating technology
www.abovetopsecret.com...