With the EPA setting new PFAS MCLs of 4 ppt for PFOA and PFOS in April 2024, millions of Americans want to know whether their water filter will protect them. The answer depends entirely on the type of filter, and most common filters do very little to remove PFAS.
The PFAS Problem
PFAS compounds are detected in 34.4% of U.S. public water systems per EPA UCMR 5 data. Even systems that comply with the new MCLs may still have PFAS at levels the EPA considers a health concern for sensitive populations. For current contamination levels by state, see SafeWater's PFAS Tracker →
Filters That DON'T Remove PFAS
Most standard household filters provide little to no PFAS removal:
- Standard pitcher filters (Brita, PUR standard): Granular activated carbon (GAC) in most pitchers is not effective for short-chain PFAS and has limited effectiveness for longer-chain compounds. Not NSF 473 certified unless specifically labeled.
- Refrigerator filters: Same issue; typically certified only for NSF 42 (taste/odor), not PFAS removal.
- Boiling water: Does not remove PFAS. Boiling concentrates PFAS by evaporating water and leaving contaminants behind.
Filters That DO Remove PFAS
Reverse Osmosis (RO)
PFAS removal rate: 90–99%
RO systems force water through a semi-permeable membrane with pores so small that PFAS molecules cannot pass through. Look for NSF/ANSI 58 certification. Point-of-use RO systems (undersink) are the most effective option available to consumers. Limitations: produces wastewater (3–4 gallons per gallon treated), removes beneficial minerals, requires installation.
Activated Carbon Block (ACB), Certified
PFAS removal rate: 73–95% for longer-chain PFAS; less effective for short-chain
Carbon block filters (not granular) can significantly reduce PFAS when certified under NSF/ANSI 473. These include some high-end pitcher filters and countertop units. Key: look specifically for NSF 473 certification, not just NSF 42 or 53.
High-Pressure Membrane Filters (Nanofiltration)
Similar to RO but less common in consumer products; effective for PFAS removal. Less water waste than standard RO.
NSF Certification Is Essential
The NSF/ANSI 58 standard (for RO) and NSF/ANSI 473 (for emerging contaminants including PFAS) are the certifications to look for. Verify any product's claims at nsf.org; certifications are publicly searchable.
The Chain Length Problem
PFAS is a family of 12,000+ compounds. Longer-chain PFAS (like PFOS and PFOA, the ones EPA now regulates at 4 ppt) are more readily removed by activated carbon. Shorter-chain replacements like GenX and PFBS are harder to remove with carbon and require RO or nanofiltration. If your water has a mix of PFAS types, RO is the safest choice.
Recommended Approach
- Test your water for PFAS (ask your utility or use a certified lab)
- If PFAS are detected above 4 ppt: install an NSF 58-certified RO system at your primary drinking tap
- If PFAS are below 4 ppt but you want additional protection: use an NSF 473-certified carbon block filter
- Replace filter cartridges on schedule; a saturated carbon filter may release trapped PFAS
See the full filter comparison guide: Best Water Filters for Removing Contaminants →