For Community Water Systems and Non-Transient Non-Community Water Systems 

Under 40 CFR Part 141, all community water systems and non-transient non-community systems must conduct initial monitoring or obtain approval to use previously collected monitoring data for per and polyfluoroalkyl substances (PFAS) by April 26, 2027. Initial monitoring requirements are based on the size of the system and the system’s source water. 

  • All Surface Water Systems regardless of population size. 
  • Quarterly within a 12-month period.  
  • Samples must be collected 2 to 4 months apart.  
  • Groundwater Systems serving more than 10,000 customers. 
  • Quarterly within a 12-month period. 
  • Samples must be collected 2 to 4 months apart.  
  • Groundwater Systems serving less than or equal to 10,000 customers. 
  • Twice within a 12-month period. 
  • Samples must be collected 5 to 7 months apart.  

Key Points to Consider

  • Sampling must be conducted at each entry point of the system, under normal/representative operating conditions.  
  • Either Monthly or Quarterly Sampling has to begin early enough for the required sampling noted above, so that the results can be submitted prior to the current deadline of April 26, 2027. 
  • To reduce costs for systems, systems can request to use previously collected monitoring data to satisfy some or all the initial monitoring requirements, if the sampling was conducted using EPA Methods 533 or 537.1 as part of UCMR 5, state-level, or other appropriate monitoring campaigns.  
  • The state of Florida has not yet obtained primacy over the PFAS requirements, in part as we are anticipating changes to the national primary drinking water regulations for PFAS in accordance with EPA’s May 14, 2025, announcement as discussed further below. Until such time the state receives approval for primacy or enters into a primacy extension, EPA Region 4 directly regulates all PFAS requirements for drinking water systems.  

On May 14, 2025, EPA announced it intended to propose changes to the current National Primary Drinking Water Regulations for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These proposed changes included reconsidering and rescinding the maximum contaminant levels for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index. EPA’s announcement also proposed to extend the compliance date for the MCLs until 2031. However, the May 14, 2025, EPA announcement did not indicate that the above initial monitoring requirements would be revised or extended by EPA.   

If you have any questions, please contact your local DEP regulatory district office or approved county health department (ACHD), or PFAS_NPDWR@FloridaDEP.gov.  

Last Modified: Thursday, Mar 12, 2026 - 07:21am