In 1986, Congress amended the Safe Drinking Water Act (SDWA) requiring the U.S. Environmental Protection Agency (USEPA) to promulgate disinfection requirements for all public-water supplies. The USEPA promulgated the Surface Water Treatment Rule (SWTR) in June 1989 to establish disinfection requirements for surface-water supplies and for ground water under the direct influence of surface water. To complete the requirements of the SDWA, the USEPA plans to propose and promulgate disinfection requirements for ground water not under the direct influence of surface water to protect the public health of persons served by those systems.