What does a 4 log disinfection level indicate?

A 4 log disinfection level represents a 99.99% reduction in the number of pathogenic organisms present in water. The term "log" refers to a logarithmic scale, which is commonly used in microbiology to quantify the effectiveness of disinfection processes. A 4 log reduction means that for every 10,000 organisms present in the water, only 1 organism remains after disinfection. This level of disinfection is critical for ensuring that water is safe for drinking and other uses, as it significantly minimizes the risk of waterborne diseases.

Understanding log reductions is important in water treatment as it helps operators ensure they are meeting public health standards. In contrast, lower log reductions, such as 3 log (99.9% reduction) or 2 log (99% reduction), indicate less effectiveness in removing pathogens, thus highlighting the importance of achieving at least a 4 log level for safe water supply.