Today the Environmental Protection Agency (EPA) is promulgating an information collection rule (ICR) which establishes monitoring and data reporting requirements for large public water systems (PWSs). This rule is intended to provide EPA with information on the occurrence in drinking water of (1) chemical byproducts that form when disinfectants used for microbial control react with chemicals already present in source water (disinfection byproducts (DBPs)) and (2) disease-causing microorganisms (pathogens), including Cryptosporidium. Also, EPA will collect engineering data on how PWSs currently control such contaminants. EPA will use information generated by this rule, along with concurrent research, to determine whether revisions need to be made to EPA's current drinking water filtration and disinfection rule and to determine the need for new regulations for disinfectants and DBPs.