Bacteria, particles, organic, and inorganic sources of contamination vary depending on a number of factors, including the feed water to make UPW, as well as the selection of the piping materials used to convey it. Bacteria are typically reported in colony-forming units (CFU) per volume of UPW. Particles use number per volume of UPW. Total organic carbon (TOC), metallic contaminants, and anionic contaminants are measured in dimensionless terms of parts per notation, such as ppm, ppb, ppt, and ppq.
