National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule

EPA is promulgating National Primary Drinking Water Regulations that require the use of treatment techniques, along with monitoring, reporting, and public notification requirements, for all public water systems that use surface water sources. The purposes of the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) are to protect public health from illness due to Cryptosporidium and other microbial pathogens in drinking water and to address risk-risk trade- offs with the control of disinfection byproducts. Key provisions in the LT2ESWTR include the following: source water monitoring for Cryptosporidium, with a screening procedure to reduce monitoring costs for small systems; risk-targeted Cryptosporidium treatment by filtered systems with the highest source water Cryptosporidium levels; inactivation of Cryptosporidium by all unfiltered systems; criteria for the use of Cryptosporidium treatment and control processes; and covering or treating uncovered finished water storage facilities. EPA believes that implementation of the LT2ESWTR will significantly reduce levels of infectious Cryptosporidium in finished drinking water. This will substantially lower rates of endemic cryptosporidiosis, the illness caused by Cryptosporidium, which can be severe and sometimes fatal in sensitive subpopulations (e.g., infants, people with weakened immune systems). In addition, the treatment technique requirements of this regulation will increase protection against other microbial pathogens like Giardia lamblia.