Top-rated 4-stage Ultra-filtration Water FilterThe iSpring #CU-A4 Ultrafiltration Water Filter System utilizes State-of-the-art UF Hollow Fiber Technology, which removes 7 log (99.99999%) of all bacteria and 6 log (99.9999%) of all protozoa. Its certified 0.1 micron (comparing to 0.2 micron in Watts UF3) absolute filter removes bacteria and protozoa at a higher rate than accepted EPA guidelines. Google CDC Ultrafiltration and find that Ultrafiltration is very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia) and bacteria (for example, Campylobacter, Salmonella, Shigella, E.