Second Unregulated Contaminant Monitoring Rule
Access Results
The Safe Drinking Water Act (SDWA) requires that once every five years the EPA issue a list of unregulated contaminants to be monitored by public water systems (PWSs).
The second Unregulated Contaminant Monitoring Rule (UCMR 2) was published on January 4, 2007. UCMR 2 required monitoring for 25 contaminants between 2008 and 2010 using analytical methods developed by the EPA and consensus organizations. This monitoring provides a basis for future actions to protect public health.
- Federal Register Notice: Revisions to the UCMR 2 for Public Water Systems, January 4, 2007
- UCMR 2 Basic Information Fact Sheet (PDF) (2 pp, 9.5 K)
UCMR 2 Scope, Analytical Methods, and Contaminants
Assessment Monitoring (AM)
All PWSs serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people monitored for 10 contaminants during a 12-month period from January 2008 through December 2010.
- UCMR 2: Fact Sheet for Assessment Monitoring (PDF) (2 pp, 9.2 K)
Screening Survey (SS)
All PWSs serving more than 100,000 people, 320 representative PWSs serving 10,001 to 100,000 people, and 480 representative PWSs serving 10,000 or fewer people monitored for 15 contaminants during a 12-month period from January 2008 through December 2010.
- UCMR 2: Fact Sheet for Screening Survey (PDF) (2 pp, 8.5 K)
The EPA paid all analytical costs associated with monitoring at PWSs serving 10,000 or fewer people.
Table 1. Contaminants, Minimum Reporting Levels, Sampling Locations, and Analytical Methods
| Contaminant | CASRN1 | Minimum Reporting Level2 | Sample Point Location3 | Analytical Method | Contaminant Classification | Monitoring Requirement |
|---|---|---|---|---|---|---|
| 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) | 5436-43-1 | 0.3 µg/L | EP | EPA 527 | Flame retardant | AM |
| 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) | 60348-60-9 | 0.9 µg/L | EP | EPA 527 | Flame retardant | AM |
| 2,2',4,4',5,5'-hexabromobiphenyl (HBB) | 59080-40-9 | 0.7 µg/L | EP | EPA 527 | Flame retardant | AM |
| 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153) | 68631-49-2 | 0.8 µg/L | EP | EPA 527 | Flame retardant | AM |
| 2,2',4,4',6-pentabromodiphenyl ether (BDE-100) | 189084-64-8 | 0.5 µg/L | EP | EPA 527 | Flame retardant | AM |
| dimethoate | 60-51-5 | 0.7 µg/L | EP | EPA 527 | Pesticide | AM |
| terbufos sulfone | 56070-16-7 | 0.4 µg/L | EP | EPA 527 | Pesticide | AM |
| 1,3-dinitrobenzene | 99-65-0 | 0.8 µg/L | EP | EPA 529 | Explosives and related compounds | AM |
| 2,4,6-trinitrotoluene (TNT) | 118-96-7 | 0.8 µg/L | EP | EPA 529 | Explosives and related compounds | AM |
| hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) | 121-82-4 | 1 µg/L | EP | EPA 529 | Explosives and related compounds | AM |
| N-nitroso-diethylamine (NDEA) | 55-18-5 | 0.005 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| N-nitroso-dimethylamine (NDMA) | 62-75-9 | 0.002 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| N-nitroso-di-n-butylamine (NDBA) | 924-16-3 | 0.004 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| N-nitroso-di-n-propylamine (NDPA) | 621-64-7 | 0.007 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| N-nitroso-methylethylamine (NMEA) | 10595-95-6 | 0.003 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| N-nitroso-pyrrolidine (NPYR) | 930-55-2 | 0.002 µg/L | EP & MR | EPA 521 | Nitrosamines; disinfection byproducts | SS |
| acetochlor | 34256-82-1 | 2 µg/L | EP | EPA 525.2 | Pesticide | SS |
| alachlor | 15972-60-8 | 2 µg/L | EP | EPA 525.2 | Pesticide | SS |
| metolachlor | 51218-45-2 | 1 µg/L | EP | EPA 525.2 | Pesticide | SS |
| acetochlor ethane sulfonic acid (ESA) | 187022-11-3 | 1 µg/L | EP | EPA 535 | Pesticide | SS |
| acetochlor oxanilic acid (OA) | 194992-44-4 | 2 µg/L | EP | EPA 535 | Pesticide | SS |
| alachlor ethane sulfonic acid (ESA) | 142363-53-9 | 1 µg/L | EP | EPA 535 | Pesticide | SS |
| alachlor oxanilic acid (OA) | 171262-17-2 | 2 µg/L | EP | EPA 535 | Pesticide | SS |
| metolachlor ethane sulfonic acid (ESA) | 171118-09-5 | 1 µg/L | EP | EPA 535 | Pesticide | SS |
| metolachlor oxanilic acid (OA) | 152019-73-3 | 2 µg/L | EP | EPA 535 | Pesticide | SS |
Notes
- Chemical Abstracts Service Registry Number (CASRN)
- The EPA-established UCMR Minimum Reporting Level (MRL) is the lowest concentration that laboratories may report to the EPA during UCMR monitoring. UCMR MRLs are determined using data from multiple laboratories that participate in the EPA’s MRL-setting studies and are not associated with contaminant health effects information. More specifically, an MRL is the quantitation limit for a contaminant that is considered achievable, with 95% confidence, by at least 75% of laboratories nationwide using a specified analytical method (recognizing that individual laboratories may be able to measure at lower levels).
- Sample Point Locations
- Entry point to the distribution system (EP)
- Distribution system at maximum residence time (MR)