Contaminant Occurrence Data in Support of the EPA's Fourth Six-Year Review of National Primary Drinking Water Regulations

The EPA is required by the Safe Drinking Water Act (SDWA), as amended in 1996, to review existing National Primary Drinking Water Regulations (NPDWRs) no less often than every six years. This routine evaluation is referred to as the “Six-Year Review of National Primary Drinking Water Regulations” or simply, the “Six-Year Review.” Throughout the Six-Year Review process, the EPA assesses new data to determine risks to human health posed by regulated drinking water contaminants and identifies NPDWRs that may be appropriate for revision. The EPA completed and published review results for the first Six-Year Review cycle (1996-2002) on July 18, 2003 (68 FR 42908). The occurrence assessments for the first Six-Year Review were based on compliance monitoring from a cross-section of 16 States, collected from 1993 to 1997, which were voluntarily provided by the States. The EPA completed and published review results for the second Six-Year Review cycle (2003-2009) on March 29, 2010 (75 FR 15500). The occurrence assessments conducted for the second Six-Year Review are based on data collected between 1998 and 2005, voluntarily submitted by States and other drinking water primary enforcement (primacy) agencies (i.e., the District of Columbia, the Commonwealth of Puerto Rico, the Virgin Islands, Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, the Trust Territory of the Pacific Islands, or an eligible Indian tribe). The EPA completed and published review results for the third Six-Year Review cycle (2010-2016) on January 11, 2017 (82 FR 3518). The occurrence assessments conducted for the third Six-Year Review are based on contaminant occurrence and treatment techniques data collected between 2006 and 2011, voluntarily submitted by States and other drinking water primacy agencies. The EPA created this new ICR to continue to engage States and other drinking water primacy agencies in data collection efforts. For this ICR, the EPA is soliciting States and other primacy agencies to (voluntarily) provide historical, compliance monitoring (contaminant occurrence) data for community water systems (CWSs) and non-transient non-community water systems (NTNCWSs) to the Agency in support of the fourth Six-Year Review. The EPA is requesting contaminant occurrence and treatment technique data collected from 2012 to 2019 for all regulated chemical, radiological, and microbial contaminants, including data collected for the Revised Total Coliform Rule, newly promulgated since the third Six-Year Review information collection. The compliance monitoring records for this information collection (including all results for analytical detections and non-detections) provide the data needed to conduct statistical estimates of national occurrence for regulated contaminants and evaluate treatment technique information associated with the control of pathogens, disinfectants, and disinfection byproducts. The national occurrence estimates and information on treatment techniques will support the EPA’s review of existing NPDWRs as required by the SDWA, section 1412(b)(9). In addition, the SDWA, section 1445(g), requires the EPA to maintain a national drinking water contaminant occurrence database (i.e., the National Contaminant Occurrence Database (NCOD)), using occurrence data for both regulated and unregulated contaminants in public water systems (PWSs). This data collection will provide new occurrence data on regulated contaminants to maintain the NCOD.

The latest form for Contaminant Occurrence Data in Support of the EPA's Fourth Six-Year Review of National Primary Drinking Water Regulations expires 2023-02-28 and can be found here.