Contaminant · PFAS

PFMBA in drinking water

CAS 863090-89-5 · EPA record reviewed 2026-09-02

Perfluoro-4-methoxybutanoic acid, an ether PFAS.

In focus10,307Systems tested nationwide

Public records. Clearer context.

Data as of EPA UCMR 5 final release, August 2026 (file dated Aug 28, 2026) · EPA SDWIS 2026Q2 (file dated Jul 9, 2026). How we build these pages

systems where it was found

of 10,307 tested

0.01%

of tested systems found it

3.0 ppt

highest single result in EPA's survey

What the rules say

PFMBA has no federal limit or EPA health reference value.

Read the EPA source for PFMBA.

Across the country

EPA tested 10,307 water systems for PFMBA and found it in 1. Half of the systems that found it measured less than 3.0 ppt, and one in ten measured more than 3.0 ppt.

EPA's final UCMR 5 occurrence file contains 66,361 PFMBA results from 10,307 systems. 2 results were at or above the minimum reporting level, across 1 systems. Among detections, the median was 3.0 ppt and the 90th percentile was 3.0 ppt.

Systems with the highest recorded PFMBA results

System	State	Population served	Recorded value	Records / periods
Iowa-American Wtr Co-Clinton District IA2326048	Iowa	24,769	3.0 ppt	2

Filters and testing

NSF/ANSI 58 (reverse osmosis)

A standard number by itself is not a contaminant claim. Check the product's current certification listing and performance data sheet for PFMBA or the specific contaminant you want to reduce. A utility-level record is not a test of your own faucet.

From the national picture to your tap

Find your county. Then read the guide.

Your areaCheck your countyPick your state and county to see the water systems that serve it and what EPA recorded for PFMBA.FiltersChoosing a PFAS filterHow to check a filter’s certified PFAS reduction before you buy.SurveyReading PFAS survey resultsWhat a detection, a reporting level and a yearly average mean in EPA’s survey.

Other PFAS in EPA’s survey

All contaminants