National Contaminant Occurrence Database (NCOD)

The National Contaminant Occurrence Database (NCOD) is maintained by the US EPA that offers access to data on the occurrence of both regulated and unregulated drinking water contaminants according to information in the Safe Drinking Water Act (SDWA). They have been collected from 1988 to present and are stored in the NCOD. Data for regulated drinking water contaminants are available from links to four, Six-Year Reviews of national drinking water regulations. The unregulated contaminants data are accessed from links to five, Unregulated Contaminant Monitoring Rule Datasets. The data include measurements of chemical, microbial, and radiological contaminants that support the EPA's regulatory decision-making when reviewing unregulated contaminants that may require future regulation under the SDWA. All of the data help support research and risk assessments and provide transparency through public access to information about drinking-water contaminants.