Robert M. Clark, PhD, is currently director of the US Environmental Protection Agency's Water Supply and Water Resources Division He has held national office in the American Society of Civil Engineers and the American Water Works Association. In 1993, Dr. Clark received the A.P. Black Award from AWWA for lifetime achievements in drinking water research. Walter M. Grayman, PhD, is an independent consulting engineer in Cincinnati, Ohio.

Dr. Grayman received a BS in civil engineering from Carnegie-Mellon University and an MS and PhD in civil engineering from the Massachusetts Institute of Technology in the area of water resources. He holds a national office in the American Society of Civil Engineers, has chaired committees of the American Water Works Association.