In June 1989, the US Environmental Protection Agency (EPA) promulgated two national regulations that will provide greater safety for consumers of public drinking water. One is the Total Coliform Rule (54 FR 27544), the other is the Surface Water Treatment Requirements (SWTR) (54 FR 27486). Both rules became effective on December 31, 1990. Because of the lack of data before 1989 on the occurrence of Cryptosporidium, and its susceptibility to treatment, the EPA decided to regulate Cryptosporidium in a future rulemaking, rather than to delay the publication of the SWTR until this data was available. The Agency is now conducting research to determine the extent to which the SWTR controls Cryptosporidium. In this paper, we will identify the major issues and research needed to control Cryptosporidium in drinking water, and mention two possible regulatory strategies for its control. In addition, because of concerns that the SWTR may not be adequate for Giardia control at many sites, this paper will also include a discussion of Giardia control on issues common to both organisms.