Darshan Singh Sarai, phd, served as lab director and water quality control specialist for Water District #1 of Johnson County, Kansas, for twenty years. For nine years, he was also chairman of the Environmental Sciences Division at the Water and Wastewater Technical School in Neosho, Missouri, where he taught microbiology, chemistry, and ecology of water and wastewater treatment. He is the author of Basic Chemistry for Water and Wastewater Operators.