PPM stands for "parts per million" and is a measuring system for the amount of substance present. In the context of ServSafe, concentration is measured in parts per million (ppm) . A test kit is used to measure the strength of sanitizers, and the kit should be made for the sanitizer being used. The amount of sanitizer to water is also measured in parts per million (ppm) . For example, the sanitizer concentration for chlorine, iodine, and quats should be between 50-99 ppm.