EPA Releases Third Round of UCMR 5 Data

On February 1, EPA released the third round of data from the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5). Every five years, EPA is required under the Safe Drinking Water Act (SDWA) to monitor for contaminants that may be present in drinking water but are not subject to National Primary Drinking Water Regulations (NPDWR). All public water systems (PWSs) serving 3,300 or more people and a representative sample of 800 systems serving 25 to 3,299 people must test for these contaminants.

UCMR 5 includes 29 PFAS and lithium, including the six PFAS in the proposed NPDWR. The data released today is the third of 12 data sets that will be released quarterly through 2026. The first three releases represent 24% of the total data that will be collected. The Agency will use this data to make determinations about future actions for these substances under SDWA. The data can be found publicly in EPA’s National Contaminant Occurrence Database. Additionally, EPA updated the UCMR 5 Data Finder, the Occurrence Data Text Files, the UCMR 5 Data Summary, the UCMR 5 Website QA, and EPA’s PFAS Analytic Tools.

The updated summary of the data noted:

  • PFOA and PFOS were measured above the EPA health advisory (HA) levels for 11.5% and 12.8% of PWSs, respectively (an increase from the second data release).
  • One PWS (out of 3,722 tested) measured HFPO-DA (“GenX chemicals”) above its HA level.
  • PFBS has still not been found above its HA level at any PWS.
  • Of the remaining 25 PFAS, 17 were measured at or above their respective Minimum Reporting Levels (MRL) by at least one PWS (an increase from the 14 reported under the second data release).
  • No PWSs have reported results at or above their respective MRLs for the final eight PFAS.
  • 25.6% of PWSs reported lithium results above EPA’s health reference level, a minor increase from the second data release.