EPA has released a report to assist drinking water systems in conducting a source water contamination threat inventory (SWCTI). An SWCTI is an actionable and detailed assessment of potential sources of contamination that can be an important element of a Source Water Assessment or a Risk and Resilience Assessment.

Through its analysis of a multistate SWCTI that looked at which of its data sources are most accessible and useful for the average water utility, EPA finds “the most complete and useful data source for conducting an SWCTI is Tier II chemical inventory data collected under the Emergency Planning and Community Right-to-Know Act (EPCRA).” Members are encouraged to read the report and it’s 2021 companion, Occurrence of Releases with the Potential to Impact Sources of Drinking Water,  to improve any SWCTI-related processes or efforts. Read more at EPA.

Clarification: Following consultation with EPA, this article has been updated to reflect that there is no federal requirement for water systems to update a SWCTI. Rather, there is the requirement for community water systems serving more than 3,300 customers to update Risk and Resilience Assessments (RRA) every five years, and one of the assets that should be considered in an RRA is source water. If an RRA indicates that source water contamination is an important threat for a community water system, they may consider conducting or updating a SWCTI to gain a deeper understanding of that specific threat. But there is no federal requirement to do so.

This article was originally titled "EPA Report Provides Guidance for Conducting Federally Mandated Updates of SWCTI." And the first paragraph, second sentence read: " An SWCTI is an actionable and detailed assessment of potential sources of contamination that can be an important element of a Source Water Assessment or a Risk and Resilience Assessment, which are required to be updated every five years under America’s Water Infrastructure Act (AWIA)."