What percentage does 4-log removal correspond to?

4-log removal refers to a process in which a microorganism population is reduced by a factor of 10,000. In logarithmic terms, each 'log' represents a tenfold reduction in the quantity of organisms. Therefore, a 1-log removal corresponds to a 90% reduction, a 2-log removal corresponds to a 99% reduction, a 3-log removal corresponds to a 99.9% reduction, and finally, a 4-log removal corresponds to a 99.99% reduction of the original number of microorganisms.

In practical terms, achieving a 4-log removal is significant in water treatment, especially for ensuring the safety and quality of drinking water by effectively eliminating pathogens. This high level of removal is essential for meeting public health standards, as it indicates a very low likelihood of remaining harmful microorganisms in the water.