The issue of microbial diseases and disinfection as impacted by regulations has been the focus of the AWWA's Microbial and Disinfection Technical Action Workgroup, formerly called the Filtration and Microbial TAW. This TAW was initially formed to impact and respond to the Surface Water Treatment Rule and the Coliform Rule, but has more recently dealt with general topics of microbial diseases and disinfection processes in the regulatory arena. The current focus of the TAW is the Groundwater Disinfection Rule and the balancing of risks between microbial issues and the disinfection byproducts rule. Major impact in the future is expected in the regulation of cryptosporidium and in dealing with the issue of viability of cysts in treated water.