Product review (1 stars): Poor Microbial Filtration
Do not buy this filter. 15 microns is not safe and will not adequately filter out dangerous bacteria or protozoa. Spend a couple dollars more and buy a good filter rated for 0.2 microns or smaller.

Most bacteria and protozoa are much smaller than 15 microns (generally 1-10 microns in size or length) and would pass right through this filter. This filter is barely adequate for drinking from a stream being fed from fresh snow melt off a mountain. It will do little more than filter out most of the dirt from contaminated water. The potential compromise of safety is not worth saving a couple dollars if you are going to place yourself in a legitimate situation where you will be far from immediate medical help and need to rely on clean water to live.

Disclaimer: I am not a medical professional or otherwise formally educated concerning biological contaminates. I am merely an avid outdoorsman and concerned citizen who has not purchased, and never will purchase, this product due to its blatant inadequacies and poorly veiled attempts to parade as a safety device. Buy at your own risk.