PLFA is a primary component of the membranes of all microbes and decomposes quickly upon cell death, so total PLFA in a sample represents all viable cells. In many situations, an accurate measure of viable biomass is critical for evaluating microbial response to environmental conditions or treatments. With bioremediation for example, contaminant biodegradation rates are often proportional to biomass concentrations so site managers often use PLFA as one means to evaluate treatments. The opposite is also true. For drinking water applications, PLFA can be used to determine whether a treatment or disinfection process decreased viable biomass.