Interim Enhanced Surface Water Treatment Rule - What Does It Mean to You?

The purpose of this guide is to detail the regulatory requirements of the Interim Enhanced Surface Water Treatment Rule (IESWTR). The IESWTR, published in the Federal Register on December 16, 1998 (63 FR 69478; www.epa.gov/OGWDW/mdbp/ieswtrfr.html; 66 FR 3770; www.epa.gov/safewater/mdbp/iesfr.html; Appendix H - rule language only), is the first part of a series of rules, the "Microbial-Disinfectants/Disinfection Byproducts Cluster" (M-DBP Cluster), to be published over the next several years that are intended to control microbial pathogens while minimizing the public health risks of disinfectants and disinfection byproducts (DBPs). The IESWTR is designed to address the health risks from microbial contaminants without significantly increasing the potential risks from chemical contaminants. This rule was published concurrently with the Stage 1 Disinfectants/Disinfection Byproducts Rule (Stage 1 DBPR), which addresses control of disinfectants and their byproducts.