National Primary Drinking Water Regulations: Monitoring Requirements for Public Drinking Water Supplies: Cryptosporidium, Giardia, Viruses, Disinfection Byproducts, Water Treatment Plant Data and Other Information Requirements

EPA is proposing to require public water systems which serve 10,000 people or greater to generate and provide the Agency with specific monitoring data and other information characterizing their water systems. Systems which use surface water, or ground water under the influence of surface water, and serve between 10,000-100,000 people would be required to (a) monitor their source water at the intake of each plant for two disease-causing protozoa, Giardia and Cryptosporidium; fecal coliforms or Escherichia coli; and total coliforms; and (b) provide specific engineering data as it pertains to removal of disease-causing microorganisms. Systems which use surface water, or ground water under the influence of surface water, and serve more than 100,000 people would be required to monitor their source water at the intake of each plant for the microorganisms indicated above, plus viruses, and, when pathogen levels exceed one pathogen/ liter in the source water, finished water for these microorganisms; monitor for certain disinfection byproducts (DBPs) as well as other water quality indicators; and provide specific engineering data as they pertain to removal of disease causing organisms and control of DBPs. All ground water systems that serve more than 100,000 people would be required to monitor for certain DBP, other water quality indicators, and to provide specific physical and engineering data. Systems which use surface water and serve more than 100,000 people and systems which use ground water and serve more than 50,000 people would be required to conduct bench or pilot scale studies to evaluate treatment performance for the removal of precursors to DBPs unless they have met certain source water or treated water quality criteria. This information will be used to consider possible changes to the current Surface Water Treatment Rule (SWTR) and to develop drinking water regulations for disinfectants and DBPs. If the SWTR is amended, information collected under this monitoring rule would assist utilities in complying with such amendments.