Fifth Unregulated Contaminant Monitoring Rule
The Safe Drinking Water Act (SDWA) requires that once every five years EPA issue a new list of unregulated contaminants to be monitored by public water systems (PWSs).
The proposed fifth Unregulated Contaminant Monitoring Rule (UCMR 5) was signed on January 14, 2021. UCMR 5, as proposed, would require sample collection for 30 chemical contaminants between 2023 and 2025 using analytical methods developed by EPA and consensus organizations. This proposed action would provide EPA, states, and communities with scientifically valid data on the national occurrence of these contaminants in drinking water. UCMR data represent one of the primary sources of national occurrence data in drinking water that EPA uses to inform regulatory and other risk management decisions for drinking water contaminant candidates.
- Pre-Publication Notice: Proposal - Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems and Announcement of a Public Meeting
- Upcoming Meetings and Materials
- UCMR 5 Fact Sheet
Proposed UCMR 5 scope, analytical methods and contaminants
Assessment Monitoring
As proposed, all PWSs serving 3,300 or more people, and 800 representative PWSs serving fewer than 3,300 would collect samples for 30 (29 per- and polyfluoroalkyl substances [PFAS] and lithium), during a 12-month period from January 2023 through December 2025.
Proposed Monitoring Design
SDWA was amended by Section 2021 of America’s Water Infrastructure Act of 2018 (AWIA). Subject to the availability of appropriations and sufficient laboratory capacity, SDWA now requires that UCMR include all large PWSs (serving >10,000 people), all PWSs serving between 3,300 and 10,000 people, and a representative sample of PWSs serving fewer than 3,300 people. Under the AWIA provisions, EPA continues to be responsible for all analytical costs associated with monitoring at systems serving 10,000 or fewer.
Table 1. Proposed UCMR 5 Scope
|
System Size (# of people served)
|
30 Contaminants |
|---|---|
| Small Systems (25 – 3,299) | 800 randomly selected surface water (SW), ground water under the direct influence of surface water (GWUDI), and ground water (GW) systems |
| Small Systems (3,300 – 10,000) | All SW, GWUDI, and GW systems |
| Large Systems (10,001 and over) | All SW, GWUDI, and GW systems |
Proposed 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. UCMR 5 includes all 29 PFAS that are within the scope of EPA Methods 533 and 537.1; see Table 2.
The UCMR 5 proposal fulfills a key commitment in EPA’s PFAS Action Plan by including the collection of drinking water occurrence data for a broader group of PFAS (i.e., building on the monitoring for six PFAS that took place under UCMR 3).
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)2 | 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)
- Although the abbreviation used is ADONA (indicating the ammonium salt), 4,8-dioxa-3H-perfluorononanoic acid is the parent acid