EPA has begun the fourth Six-Year Review process. Throughout the Six-Year Review process, EPA reviews and assesses new data, information and technologies and identifies NPDWRs which may be appropriate for revision. Six-Year Review 4 results are anticipated to be completed in early 2023.

June 3, 2020 — EPA sent a data call letter to all primacy agencies requesting the voluntary submission of contaminant occurrence data and treatment technique information collected from 2012 to 2019 for all regulated contaminants. EPA is encouraging each primacy agency to submit their data to improve EPA's understanding of regulated contaminants in drinking water and help decide whether existing regulations need to be revised. The collection has been approved by OMB (Control Number 2040-0298).

October 31, 2019 —The Federal Register Notice announcing EPA’s submission of the ICR to OMB for review and approval, and an additional public comment period was published. The deadline for public comment was December 2, 2019. The notices and the ICR Supporting Statement associated with each notice can be found in docket number EPA-HQ-OW-2018-0241.

October 5, 2018 —The Federal Register Notice announcing the proposed Information Collection Request (ICR) for Contaminant Occurrence Data in Support of the Fourth Six-Year Review was published. The first three Six-Year Reviews were supported by Office of Management and Budget (OMB) approved information collections. The notice proposes an information collection to support the fourth Six-Year Review. Before submitting the ICR to OMB for approval, EPA solicited public comments on specific aspects of the proposed, voluntary information collection. The deadline for public comment was December 4, 2018.