The US Environmental Protection Agency (USEPA) has been working to develop new regulations for microbes and disinfection byproducts (M/DBPs) since the early 1980s. The agency's drinking water program redirection effort in 1995 elevated the control of high-risk microbial contaminants and resulted in the M/DBP cluster of rules becoming a top agency priority. The 1996 Safe Drinking Water Act (SDWA) amendments require the agency to meet aggressive deadlines for regulation of M/DBPs. Key milestones and deadlines in the regulation of disinfectants and DBPs (D/DBPs) are summarized in this article. Includes 7 references.