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Water: Unregulated Contaminant Monitoring Program

Occurrence Data: Accessing Unregulated Contaminant Monitoring Data

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EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for contaminants suspected to be present in drinking water, but do not have health-based standards set under the Safe Drinking Water Act (SDWA). The data assist the Administrator in determining whether or not to regulate those contaminants.

  • Learn more about the UCMR.

UCMR 2 (2008-2010) Occurrence Data

The Unregulated Contaminant Monitoring Rule supporting the second cycle (UCMR 2) of monitoring, conducted under EPA oversight, was published in the Federal Register on January 4, 2007. The UCMR 2 required monitoring for 25 contaminants using five analytical methods.

  • UCMR 2 Occurrence Data (3.4MB ZIP File, January 2012)
  • The ZIP FILE contains:
    • UCMR 2 Data Considerations, Definitions and Summary PDF
    • UCMR 2 Occurrence Data Text File

The following data is a subset of the above data organized by method classification.

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UCMR 1 (2001-2005) Occurrence Data

The Unregulated Contaminant Monitoring Rule supporting the first cycle (UCMR 1) of monitoring, conducted under EPA oversight, was published in the Federal Register on September 17, 1999. The UCMR 1 required monitoring for 26 contaminants. Monitoring occurred January 2001-December 2005.

Some untreated source water data is included in these tables, but any positive result from source waters, which are subsequently treated, are not expected to be used to conduct exposure assessments. To the extent that positive results from monitoring source water that is subsequently treated are included in the table, these source water positive data are presented simply for informational purposes; in such cases, the results of additional finished water monitoring (at the entry point to the distribution system) were reported to EPA and appear in this table. Caution should be used in any interpretation of the subject data, since this table contains ALL data reported for UCMR 1, including raw source water data.

Data included in UCMR PivotTable®

This PivotTable contains information on UCMR sample results reviewed by EPA. Any or all of the following facts for a contaminant-

  • # analyses performed
  • # PWSs with analyses
  • # PWSs with detects (analytical detections above the reporting limit)
  • minimum detect
  • maximum detect
  • average detect
- can be categorized by any combination of the following water system attributes:
  • EPA Region
  • Geography type-state, tribal, territory
  • State
  • Primary county served
  • Water system type
  • Size category
  • Primary source of water
  • Owner type

- or any combination of the following sample attributes:

  • Detects only or all analyses
  • Minimum Reporting Level for an analytical method and contaminant
  • Unit of measure
  • Sample collection month and year
  • Sample point type
  • Sample analysis type
  • Analytical method

Details on these attributes are provided in the PivotTable.

You can double-click on any data cell to obtain PWS-level and sample-level information.

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UCM-State Rounds 1 and 2 (1988-1997) Occurrence Data

The Unregulated Contaminant Monitoring-State (UCM-State) Round 1 dataset contains public water system (PWS) monitoring results for 62 then unregulated contaminants (some of them have since been regulated). These data were collected by 40 states and primacy entities between 1988 and 1992. The Round 2 dataset contains PWS monitoring results for 48 then unregulated contaminants. These data were collected by 35 states and primacy entities between 1993 and 1997.

Rounds 1 & 2 contaminant occurrence data

Data included in Rounds 1 & 2 PivotTable - This PivotTable contains information on Rounds 1 & 2 sample data. Any or all of the following facts for a contaminant-

  • # analyses performed
  • # PWS with analyses
  • # detects
  • # PWS with detects
  • minimum detect
  • maximum detect
  • mean detect
-can be categorized by any combination of the following water system attributes:
  • EPA Region
  • State
  • Water system type
  • Size category *
-or any combination of the following sample attributes:
  • Which Round the sample is from *
  • Whether the data was included in the national cross-section (which is a function of the State and the Round)
  • Sample collection year *
  • Source water type where the sample was taken *

* To avoid double-counting, the Pivot Tables will not sum the number of PWSs with and without detects across this dimension/attribute. Details on these attributes are provided in the PivotTables

Data fields included in the Rounds 1 & 2 database table

  • PWSID (Pubic Water System Identification Code)
  • EPA region
  • State
  • In national cross-section?
  • Water system type
  • Size category (based on people served by the system)
    • 1 = Very Small  <=500
    • 2 = Small          501-3,300
    • 3 = Medium       3,301-10,000
    • 4 = Large          10,001-100,000
    • 5 = Very large    >100,000
  • Population served by the system
  • Source_type
  • Contaminant Code
  • Contaminant Name
  • Detect?
  • NonDetect?
  • Result (for detects)
  • Sample collection date
  • Round (sample collected in Round 1 or Round 2)

Details on these attributes are provided in the Pivot Tables

About MS Excel PivotTables®

To use these tables you'll need MS Excel 97 or later version. Detailed instructions are available for downloading, and summary instructions are included in each PivotTable. No prior knowledge of spreadsheets is required.

PivotTables are multidimensional databases (MDBs) that provide online analytical processing, or OLAP. They enable you to quickly summarize, cross-tabulate, and analyze large amounts of data. You can pivot, or rotate, rows and columns to see different summaries of the source data, filter the data, and drill-down to the details in the underlying source data.

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