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Data report · updated November 2026

Tap Water Report 2026: what’s in the tap water of 40 US water systems

These 40 systems serve about 55.8 million people directly and about 74.3 million counting the systems that buy water from them.

Short answer

11 of the 40 systems had at least one PFOA or PFOS (two PFAS “forever chemicals”) sample above the U.S. Environmental Protection Agency’s (EPA’s) 4 parts per trillion (ppt) limit in its 2023–25 testing; the highest was Miami, where PFOS reached 33.0 ppt. 11 had lithium above EPA’s 10 micrograms per liter (µg/L) health reference level, led by Phoenix at 160 µg/L. By the utilities’ own reports, 6 have very hard water and 6 have soft water.

EPA UCMR 5 (2023–25), EPA SDWIS 2026Q3, utility water quality reports · Sources and method

Download the data (CSV)How we built it

01 · Findings

What the numbers show

11of 40

had a PFOA or PFOS sample above EPA’s 4 ppt limit

These are single samples from EPA’s national testing, not violations. Utilities must meet the limit by 2029, judged on a yearly average. In May 2026 EPA proposed giving utilities that request it until 2031; that proposal isn’t final.

11of 40

had lithium above EPA’s 10 µg/L health reference level

Highest sample in µg/L. Lithium has no legal limit; the reference level is a screening benchmark, and about 24% of large systems nationwide tested above it.

0.5 to 18.5grains per gallon

Hardness runs from Portland, the softest, to Indianapolis, the hardest

Hardness is the reading that decides whether a softener is worth buying. 6 systems have very hard water (over 10.5 grains per gallon) and 6 have soft water.

6of 40

utilities don’t publish hardness in their annual water quality report

Hardness has no federal limit, so the reports don’t have to include it. Homeowners there can ask the utility or test it themselves.

21of 40

use chloramine in all or part of their system

That decides which filter removes the taste: ordinary carbon takes out chlorine quickly but chloramine slowly, so chloramine needs catalytic carbon.

4of 40

had a health-based violation in the five years through September 2026

Each of those city pages lists the violations and their dates, in plain words, from EPA’s federal drinking water database.

Bar chart of the highest PFOA or PFOS sample in EPA's 2023-25 testing for 11 large US water systems, against EPA's 4 ppt limit. 29 other systems had none detected.
Use this chart:Download imageFree to reuse with credit (CC BY 4.0).

Hardness, by city

0 to 300 mg/L as calcium carbonate

  1. Indianapolis18.5
  2. San Antonio17.5
  3. Las Vegas16.4
  4. Jacksonville14.4
  5. San Diego14.0
  6. Tampa10.8
  7. El Paso10.2
  8. Philadelphia8.9
  9. Albuquerque8.8
  10. San Jose8.8
  11. Washington8.1
  12. Milwaukee8.1
  13. Dallas8.0
  14. Houston7.9
  15. Fort Worth7.5
  16. Los Angeles7.5
  17. Louisville7.5
  18. Cincinnati7.5
  19. Cleveland6.8
  20. Columbus6.7
  21. Detroit6.3
  22. Denver6.1
  23. Nashville5.9
  24. Kansas City5.8
  25. Baltimore5.5
  26. Minneapolis5.5
  27. Austin5.4
  28. San Francisco3.6
  29. Memphis2.8
  30. New York1.9
  31. Charlotte1.9
  32. Seattle1.5
  33. Boston0.9
  34. Portland0.5
Each dot is the utility’s published average or range midpoint; the outline shows its published range. Classes per USGS. Source: each utility’s latest water quality report.
Use this chart:Download imageFree to reuse with credit (CC BY 4.0).

02 · The data

Every system

CityHardnessgpgHardness classDisinfectantPFOA highpptPFOS highpptLithium highµg/LHealth violations5 years
Albuquerque, NM8.8HardFree chlorinenonenone710
Atlanta, GAnot publishedFree chlorinenonenonenone0
Austin, TX5.4Moderately hardChloraminenone4.8none1
Baltimore, MD5.5Moderately hardFree chlorinenonenonenone3
Boston, MA0.9SoftChloraminenonenonenone0
Charlotte, NC1.9SoftFree chlorinenonenonenone0
Chicago, ILnot publishedFree chlorinenonenonenone0
Cincinnati, OH7.5HardFree chlorinenone6.1none0
Cleveland, OH6.8Moderately hardFree chlorinenonenonenone0
Columbus, OH6.7Moderately hardFree chlorine5.3nonenone0
Dallas, TX8.0HardChloramine6.35.1none0
Denver, CO6.1Moderately hardChloraminenonenone110
Detroit, MI6.3Moderately hardFree chlorinenonenonenone0
El Paso, TX10.2HardFree chlorinenone8.51330
Fort Worth, TX7.5HardChloramine8.37.3none0
Houston, TX7.9HardChloraminenonenone341
Indianapolis, IN18.5Very hardChloraminenonenonenone0
Jacksonville, FL14.4Very hardFree chlorinenonenone140
Kansas City, MO5.8Moderately hardChloraminenonenone590
Las Vegas, NV16.4Very hardFree chlorinenonenone430
Los Angeles, CA7.5HardChloraminenonenone1000
Louisville, KY7.5HardChloramine7.5nonenone0
Memphis, TN2.8SoftFree chlorinenonenonenone0
Miami, FLnot publishedChloramine14.033.0none0
Milwaukee, WI8.1HardChloraminenonenonenone0
Minneapolis, MN5.5Moderately hardChloraminenonenonenone0
Nashville, TN5.9Moderately hardFree chlorinenonenonenone0
New York, NY1.9SoftFree chlorinenonenonenone0
Oklahoma City, OKnot publishedChloraminenonenone680
Philadelphia, PA8.9HardChloramine8.16.0none0
Phoenix, AZnot publishedFree chlorinenonenone1600
Portland, OR0.5SoftChloraminenonenonenone0
San Antonio, TX17.5Very hardFree chlorinenonenone260
San Diego, CA14.0Very hardChloraminenonenone650
San Francisco, CA3.6Moderately hardChloraminenonenonenone0
San Jose, CA8.8HardChlorine and chloraminenone6.2101
Seattle, WA1.5SoftFree chlorinenonenonenone0
Tampa, FL10.8Very hardChloramine4.66.9none0
Tucson, AZnot publishedFree chlorinenonenone640
Washington, DC8.1HardChloraminenonenonenone0
  • Red: above EPA’s level. That’s 4 parts per trillion (ppt) for PFOA and PFOS. For lithium it’s 10 micrograms per liter (µg/L), a health reference level rather than a legal limit, which EPA compares at one significant digit, so up to 15 µg/L counts as at the level.
  • "None" means not detected. "High" is the highest single sample.
  • Sources: hardness from each utility’s published water quality data; PFAS and lithium from EPA’s national testing (UCMR 5), sampled mostly 2023 to 2025; violations from EPA’s federal drinking water database (SDWIS).

03 · Use it

Using this data

The data is free to use under a Creative Commons Attribution license (CC BY 4.0). Please credit "The Water Monitor" and link this page. The CSV has one row per system, with the EPA system ID and the URL of the utility report each hardness figure came from.

Suggested citation: The Water Monitor, "Tap Water Report 2026," thewatermonitor.com/report/, November 2026.

Sources

  1. 01EPA, Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) occurrence data, file posted 2026-10-15
  2. 02EPA, Safe Drinking Water Information System via ECHO, 2026Q3 file
  3. 03EPA, PFAS National Primary Drinking Water Regulation, 89 FR 32532
  4. 04EPA UCMR 5 Data Summary (July 2026)
  5. 05Utility water quality reports (one per system, linked on each city page and in the CSV)