Fifth Unregulated Contaminant Monitoring Rule
The Safe Drinking Water Act (SDWA) requires that once every five years EPA issue a list of unregulated contaminants to be monitored by public water systems (PWSs).
The fifth Unregulated Contaminant Monitoring Rule (UCMR 5) was published on December 27, 2021. UCMR 5 requires sample collection for 30 chemical contaminants between 2023 and 2025 using analytical methods developed by EPA and consensus organizations. This action provides EPA and other interested parties with scientifically valid data on the national occurrence of these contaminants in drinking water. Consistent with EPA’s PFAS Strategic Roadmap, UCMR 5 will provide new data that is critically needed to improve EPA’s understanding of the frequency that 29 PFAS (and lithium) are found in the nation’s drinking water systems and at what levels. This data will ensure science-based decision-making and help prioritize protection of disadvantaged communities.
- 40 CFR (Code of Federal Regulations, Title 40) Part 141: Final - Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems and Announcement of Public Meetings (pdf) (27 pp, 650 K, About PDF)
- Press Release: EPA Takes Action to Address PFAS in Drinking Water
-
UCMR 5 Program Overview Fact Sheet (pdf)
- Hoja informativa del programa (pdf) (Spanish Version)
- Health-Based Reference Values for UCMR 5
- Sample Collection Training Video for Small Public Water Systems
- EPA Approved Laboratories for UCMR 5
UCMR 5 Scope, Analytical Methods and Contaminants
Monitoring Scope
All PWSs serving more than 10,000 people (i.e., large systems) will monitor; all PWSs serving 3,300 to 10,000 people, and 800 representative PWSs serving fewer than 3,300 will monitor, subject to availability of appropriations and sufficient laboratory capacity. PWSs will collect samples for 29 per- and polyfluoroalkyl substances (PFAS) and lithium, during a 12-month period from January 2023 through December 2025. If EPA does not receive the appropriations needed in a given year, then a reduced number of small systems will perform monitoring. As EPA finalizes its sampling design plan for each sample collection year, the Agency will notify the participating small systems. EPA is undergoing its planning anticipating that necessary appropriations will become available.
EPA continues to be responsible for all analytical costs associated with monitoring at systems serving 10,000 or fewer. See table below for the monitoring design.
Table 1. UCMR 5 Monitoring Scope
|
System Size (# of people served)
|
System Participation in Monitoring for 30 Contaminants |
|---|---|
| Small Systems (fewer than 3,000) | 800 randomly selected surface water (SW), ground water under the direct influence of surface water (GWUDI), mixed sources (MX) and ground water (GW) systems |
| Small Systems (3,300 – 10,000) | All SW, GWUDI, MX, and GW systems |
| Large Systems (10,001 and over) | All SW, GWUDI, MX, and GW systems |
Contaminants and Analytical Methods
SDWA was amended by Section 7311 of the National Defense Authorization Act (NDAA) for Fiscal Year 2020. NDAA specifies that EPA shall include all PFAS in UCMR 5 for which a drinking water method has been validated, and that are not subject to a national primary drinking water regulation. In addition to lithium, UCMR 5 includes all 29 PFAS that are within the scope of EPA Methods 533 and 537.1; see Table 2.
Table 2. Contaminants, Minimum Reporting Levels, Sampling Locations, and Analytical Methods
Twenty-nine Per- and Polyfluoroalkyl Substances
| Contaminant | Chemical Abstract Service Registry Number (CASRN) | Minimum Reporting Level | Sample Point Location1 | Analytical Methods |
|---|---|---|---|---|
| 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) | 763051-92-9 | 0.005 µg/L | EPTDS | EPA Method 533 |
| 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS) | 756426-58-1 | 0.002 µg/L | EPTDS | EPA Method 533 |
| 4,8-dioxa-3H-perfluorononanoic acid (ADONA) | 919005-14-4 | 0.003 µg/L | EPTDS | EPA Method 533 |
| hexafluoropropylene oxide dimer acid (HFPO DA) | 13252-13-6 | 0.005 µg/L | EPTDS | EPA Method 533 |
| nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | 151772-58-6 | 0.02 µg/L | EPTDS | EPA Method 533 |
| perfluorobutanoic acid (PFBA) | 375-22-4 | 0.005 µg/L | EPTDS | EPA Method 533 |
| perfluorobutanesulfonic acid (PFBS) | 375-73-5 | 0.003 µg/L | EPTDS | EPA Method 533 |
| 1H,1H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS) | 39108-34-4 | 0.005 µg/L | EPTDS | EPA Method 533 |
| perfluorodecanoic acid (PFDA) | 335-76-2 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluorododecanoic acid (PFDoA) | 307-55-1 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluoro(2-ethoxyethane)sulfonic acid (PFEESA) | 113507-82-7 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluoroheptanesulfonic acid (PFHpS) | 375-92-8 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluoroheptanoic acid (PFHpA) | 375-85-9 | 0.003 µg/L | EPTDS | EPA Method 533 |
| 1H,1H, 2H, 2H-perfluorohexane sulfonic acid (4:2FTS) | 757124-72-4 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluorohexanesulfonic acid (PFHxS) | 355-46-4 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluorohexanoic acid (PFHxA) | 307-24-4 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluoro-3-methoxypropanoic acid (PFMPA) | 377-73-1 | 0.004 µg/L | EPTDS | EPA Method 533 |
| perfluoro-4-methoxybutanoic acid (PFMBA) | 863090-89-5 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluorononanoic acid (PFNA) | 375-95-1 | 0.004 µg/L | EPTDS | EPA Method 533 |
| 1H,1H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) | 27619-97-2 | 0.005 µg/L | EPTDS | EPA Method 533 |
| perfluorooctanesulfonic acid (PFOS) | 1763-23-1 | 0.004 µg/L | EPTDS | EPA Method 533 |
| perfluorooctanoic acid (PFOA) | 335-67-1 | 0.004 µg/L | EPTDS | EPA Method 533 |
| perfluoropentanoic acid (PFPeA) | 2706-90-3 | 0.003 µg/L | EPTDS | EPA Method 533 |
| perfluoropentanesulfonic acid (PFPeS) | 2706-91-4 | 0.004 µg/L | EPTDS | EPA Method 533 |
| perfluoroundecanoic acid (PFUnA) | 2058-94-8 | 0.002 µg/L | EPTDS | EPA Method 533 |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | 2991-50-6 | 0.005 µg/L | EPTDS | EPA Method 537.1 |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | 2355-31-9 | 0.006 µg/L | EPTDS | EPA Method 537.1 |
| perfluorotetradecanoic acid (PFTA) | 376-06-7 | 0.008 µg/L | EPTDS | EPA Method 537.1 |
| perfluorotridecanoic acid (PFTrDA) | 72629-94-8 | 0.007 µg/L | EPTDS | EPA Method 537.1 |
One Metal
| Contaminant | Chemical Abstract Service Registry Number (CASRN) | Minimum Reporting Level | Sample Point Location1 | Analytical Methods |
|---|---|---|---|---|
| lithium | 7439-93-2 | 9 µg/L | EPTDS | EPA Method 200.7; SM 3120 B (2017); SM 3120 B-99 (1999); ASTM D1976-20 |
Notes
- Sampling Locations - Entry points to the distribution system (EPTDS)