Most Americans get tap water with no health-based violations, but it isn't risk-free. In EPA's 2025 violation records, Hawaii comes out best, with no residents affected. New York looks worse by 51%, mostly because of one New York City treatment violation. Louisiana and West Virginia rank low on both of our measures.
Before you hunt for your state, one thing matters more than any rank. A state rank is not your tap. A state near the bottom doesn't mean every water system in it is failing, and a state near the top can still have a struggling utility. What comes out of your faucet depends on your own utility provider; see "How to check your own water" below.
Which states have the best and worst tap water?
We ranked the states two ways, because one number can mislead. The first counts people: the share of a state's residents served by a community water system with at least one health-based violation in 2025. (That means a system went over a contaminant limit, missed a required disinfection level, or skipped a required treatment step. Late paperwork doesn't count.) The second counts systems: the share of a state's water systems with one. Rank 1 is the lowest share. Nationally, 7.3% of people on community water systems were on one with a health-based violation, by BOROUX's calculation from EPA data.
The 10 best states
| Rank by people | State | % of residents on a system with a violation | Rank by systems | % of systems with a violation |
|---|---|---|---|---|
| 1 | Hawaii | 0.0 | 1 | 0.0 |
| 2 | Florida | 0.07 | 2 | 1.0 |
| 3 | Delaware | 0.07 | 5 | 1.94 |
| 4 | North Dakota | 0.2 | 6 | 1.97 |
| 5 | Connecticut | 0.22 | 27 | 5.49 |
| 6 | Washington | 0.28 | 8 | 2.34 |
| 7 | California | 0.45 | 23 | 4.98 |
| 8 | Maine | 0.6 | 29 | 5.96 |
| 9 | Maryland | 0.67 | 11 | 2.8 |
| 10 | Iowa | 0.71 | 3 | 1.57 |
The 10 worst states
| Rank by people | State | % of residents on a system with a violation | Rank by systems | % of systems with a violation | Why it lands here |
|---|---|---|---|---|---|
| 42 | New Jersey | 7.52 | 40 | 9.55 | Lead and Copper Rule is the most common family; the largest system is 32.4% of affected residents |
| 43 | Mississippi | 9.83 | 20 | 4.55 | One system is 60.2% of affected residents; Groundwater Rule is the most common family |
| 44 | Massachusetts | 9.99 | 18 | 3.98 | Boston Water and Sewer Commission is 67.8% of affected residents (lead service line replacement, open since Nov 2020) |
| 45 | New Mexico | 12.18 | 48 | 29.03 | A high share of systems, mostly groundwater-rule issues; no one system dominates (23.0% is the largest) |
| 46 | Texas | 13.16 | 36 | 8.42 | Houston's May 2025 turbidity violation is 68.0% of affected residents |
| 47 | Oklahoma | 15.14 | 47 | 22.83 | Many systems, but no single dominant one; the largest is only 6.3% |
| 48 | West Virginia | 16.56 | 50 | 31.4 | Nearly one-third of systems have a violation; the largest is 11.6% |
| 49 | Oregon | 18.78 | 31 | 7.14 | Portland's failure-to-filter violation is 94.6% of affected residents |
| 50 | Louisiana | 24.82 | 49 | 31.28 | Both shares are high; the largest system, New Orleans, is 25.8% |
| 51 | New York | 51.16 | 7 | 2.31 | One New York City treatment violation is 88.1% of affected residents |
Source: EPA ECHO SDWA download, file dated July 9, 2026; calendar year 2025; BOROUX analysis. A state on this list does not mean every water system in that state is failing.
Two states jump out. New York is last by people but 7th best by systems, and Oregon is 49th by people but 31st by systems. In both, one big city does most of the work. Louisiana, West Virginia, New Mexico and Oklahoma are different: they rank low on both. First, here is how we built the numbers, so you can check them.
How did we rank the states?
EPA doesn't publish an official best-and-worst list. This is BOROUX's analysis of EPA's public enforcement records, with no EWG data and no other group's rankings mixed in.
We counted active community water systems, meaning the utilities that serve the same homes year-round, in the 50 states and Washington, DC. That's 48,100 systems serving about 326.2 million people. Private wells, tribal and EPA-direct systems, and the territories are left out, and Puerto Rico is reported separately, with 402 community water systems and 38% of its served population on a system with a health-based violation.
One category didn't make the cut. EPA flags a missed deadline to file a lead service line inventory (code 2E) as health-based. It's a paperwork failure, not a water test result, and EPA's own 2024 report ties that year's jump in health-based violations to it. So we excluded it. Counting it would move the national figure from 7.3% to 9.3%. A different code, lead service line replacement (code 64), is a real treatment requirement, so it stays in.
Does it match EPA's own count? Nearly. EPA's 2024 national compliance report counts 10,769 public water systems with a health-based violation. Counting violations that began in 2024, across all system types and with the lead-inventory code included, our file gives 10,887, about 1% higher. Two gaps we could not close. For 2023, our file shows 4,897 systems against EPA's 6,045, which is 19% lower. And it shows 6,564 systems with the lead-inventory violation against EPA's 3,902. We're telling you rather than quietly adjusting for them.
The numbers have limits, too. States report differently, so a state that reports diligently can look worse. Small states swing more: Hawaii has 118 systems and Washington, DC has 4. A system deactivated during 2025 is missing, and fourth-quarter data may still be revised. The state-level data file and the script are available on request.
The settings and codes, for anyone checking our work:
- Data: EPA ECHO SDWA bulk download, file dated July 9, 2026 (latest quarter: 2026 Q2), retrieved September 30, 2026
- Year and universe: calendar year 2025, counting any violation whose noncompliance period overlapped it; active community water systems (CWS), assigned to the state in the first two letters of the EPA system ID
- Health-based violations: exceeding a maximum contaminant level (MCL) or maximum residual disinfectant level (MRDL), or failing a treatment technique (TT) requirement
- Codes: 2E "LSL Inventory" excluded; 64 "Lead Service Line Replacement" kept
- Measures: the two rankings correlate at 0.54 (Spearman), so both appear
EPA describes the file in its ECHO SDWA download summary and its drinking water FAQ. The national comparison is from EPA's 2024 public water system compliance report.
So how does a state land last when nearly all of its systems are fine?
Why can one city move a whole state's ranking?
Take New York. Seeing 51.2% of New Yorkers on a system with a violation sounds like a lot, so here's what's behind it. New York City's water system serves about 8.27 million people and has had an open treatment-technique violation since February 1, 2017. A treatment technique is a required step, like filtering surface water, rather than a cap on how much of something can be in the water. This one is coded "Treatment Technique Uncovered Reservoir," under the Long Term 2 Enhanced Surface Water Treatment Rule: a required step for an uncovered reservoir wasn't met. That's a regulatory violation, not a contaminant reading from anyone's sink.
Because the people measure counts residents, that one open item makes up 88.1% of New York's figure. Meanwhile only 2.31% of New York's systems had a health-based violation in 2025, the 7th best share in the country. Both are true: New York is last by people, and nearly all of its systems had no health-based violation that year.
Oregon works the same way. The Portland Water Bureau serves about 666,200 people and accounts for 94.6% of Oregon's figure. Its violation, coded "Failure to Filter (SWTR)," has been open since December 18, 2017, under the same Long Term 2 rule. That's why Oregon is 49th by people and 31st by systems.
In Massachusetts, the Boston Water and Sewer Commission serves about 676,000 people and makes up 67.8% of the state's figure. Its violation is for lead service line replacement (code 64), open since November 1, 2020. That is a violation of a replacement requirement, not a lead test result from any home.
Louisiana and Texas each have a big city with a 2025 turbidity violation. Turbidity means cloudiness, and these are treatment-plant rules, not results from a home tap. New Orleans Carrollton Water Works (about 334,900 people) had a "Monthly Turbidity Exceed (Enhanced SWTR)" violation, code 44, and is Louisiana's largest single contributor at 25.8%. Louisiana is also 49th by systems, though, so one city doesn't explain its rank. The City of Houston (about 2.97 million people) had a "Single Turbidity Exceed (Enhanced SWTR)" violation, code 43, in May 2025, and accounts for 68.0% of Texas's figure.
So read "New York is worst" as "one very large system has had a treatment requirement open since 2017." It tells you little about the water in your kitchen. The last column of the full table shows which other states lean on one system this way. It's also one reason lists can't agree.
Why do tap water rankings disagree?
If you've seen "worst states" lists that contradict each other, the data isn't broken. Each publisher counts something different: raw violations, people, systems, or contaminants measured against a health guideline that isn't EPA's legal limit.
| Publisher and date | What it measures | Data years | A state that ranks very differently |
|---|---|---|---|
| Afina study, via Newsweek (Jan 2026) | 40% violation points per 100 residents + 60% contaminants in violation per 100 residents | Violations over 5 years, contaminants over 3 years | West Virginia scores 0 of 100; Hawaii is near the top |
| TapWater.org (Jan 2026) | Violations normalized by population and system count, with contaminants weighted | EPA, EWG, J.D. Power and USGS data, 2020-2025 | Texas is listed worst |
| US Water Grade (2026) | Population-weighted city grades from health-based violations, lead results and PFAS monitoring | EPA SDWIS | Oklahoma grades A; New York and Florida grade lowest |
| Newsweek raw-count map (Jan 2025) | Raw count of EPA SDWA violations | 2023 | Pennsylvania has the most; Hawaii has very few |
| Pentair (Jul 2021) | Share of public water systems compliant | 2021 | West Virginia lowest at 34% |
| Clearly Filtered, 2026 edition (Dec 2025) | Count of contaminants detected in EWG's Tap Water Database (cited by attribution only) | EWG data; years not stated by the publisher | Texas and New York show the highest counts |
| BOROUX, this page | Share of residents and share of systems with a health-based violation | EPA ECHO, calendar 2025 | Hawaii 0%; New York worst by people, 7th best by systems |
Each row is the publisher's own stated method, not an endorsement or a criticism.
Oklahoma shows the split best. US Water Grade gives it an A, the Afina study puts it near the bottom, and in our EPA 2025 table it is 47th on both measures. All three can be true, because each measures something different. Pennsylvania tops the raw-count map partly because it has about 8,000 public water systems, which is a lot of places to record a violation; in our table it is 36th by people and 42nd by systems. The water didn't change between lists. What each list divides by did.
Per-person scores have their own catch. The Brockovich Report quotes Natalie Exum, who works in environmental health. She noted that violations can stem from many factors and that normalizing by population size might inflate scores for smaller systems. EPA adds that states monitor and report differently. That's why we show two measures.
Whichever list you trust, what sits behind these violations, and could a filter on your counter touch any of them?
What are the most common violations, and can a filter help?
It depends on the violation. In our full table, the most common rule family is the Groundwater Rule in 16 states, the Stage 2 disinfection byproducts rule in 14, and the Lead and Copper Rule in 8. Those are very different problems, and a home filter handles some and not others.
Two standards come up in the table. NSF/ANSI 53 is the standard for filters that reduce health-related contaminants, and a product's listing names each contaminant it was tested for. "Check a 53 listing" means: look for the contaminant by name.
| Violation family | Does a carbon block filter address it? | Depends on the filter? | Reduced by BOROUX Foundation Filter? (evidence type) | What to do instead |
|---|---|---|---|---|
| Total coliform / RTCR (microbial indicators) | No | No | Not intended. The BOROUX Foundation is not intended to filter microorganisms. | Follow your utility's notice. Use a treatment intended for microbiological safety, such as UV or distillation. See the micron rating explainer. |
| Nitrate | No | No | Not claimed (absent from the test report) | Reverse osmosis, anion exchange, or distillation. Do not boil; boiling concentrates nitrate. |
| Arsenic | No | No | Not claimed (absent from the test report) | Reverse osmosis, adsorptive media, anion exchange, or distillation. |
| DBPs: TTHM (total trihalomethanes) | Generally yes. WQA says activated carbon can often filter out chlorine disinfection byproducts. | Yes. Check a 53 listing naming THMs or VOCs. | Independent lab test report (IAPMO R&T Lab): chloroform, the test's stand-in for VOCs, 300 → 4.4 µg/L over 200 gal. THM rows show the same value. | Check a 53 listing naming THMs or VOCs. See the trihalomethanes explainer. |
| DBPs: HAA5 (haloacetic acids) | Some. Carbon can treat disinfection byproducts, but HAA5 is a separate group. | Yes. Check a 53 listing naming HAA5. | Not claimed as a group; only tribromoacetic acid appears in the report's surrogate rows | Check a 53 listing naming haloacetic acids. |
| Lead and Copper Rule | For lead, some carbon block filters can reduce it. Copper: not listed for carbon in the sources reviewed. | Lead: yes. Check a 53 listing naming lead. "Lead-free" (NSF/ANSI/CAN 372) describes a filter's materials, not lead reduction. | Lead, test report (IAPMO R&T Lab; R&D test to the 53 lead protocol, not a 53 certification): 150 → 1.7 µg/L over 4,000 gal at pH 6.5; 150 → 1.6 µg/L over 450 gal at pH 8.5. Copper: Not claimed. | Check a 53 listing naming lead or copper. See the lead explainer. |
| Surface water treatment / turbidity | No. This is a treatment-plant requirement, not a point-of-use fix. | No | Not applicable; no microorganism claim. | Follow your utility's notice. This is a system-level issue. |
| Radionuclides (radium, uranium, gross beta) | Radium: no. Uranium and gross beta: not listed for carbon in the sources reviewed. | Radium: no. Uranium: Minnesota Department of Health lists anion exchange, adsorptive media and reverse osmosis. | Uranium, test report (IAPMO R&T Lab): 97 → 4.3 µg/L over 500 gal. Gross beta (cesium), test report: 200 → 4.4 pCi/L over 50 gal. Radium: Not claimed. | For radium: softening, reverse osmosis, or distillation, per WQA guidance. |
| PFAS (UCMR 5 occurrence, not a compliance family) | Some carbon filters can reduce PFAS; filter design matters. | Yes. Check a 53 listing naming PFAS, PFOA or PFOS. | Total PFAS, test report (IAPMO R&T Lab; R&D test to the 53 PFAS protocol, not a 53 certification): 2 → 0.01 µg/L over 400 gal. PFBS and PFDA: no effluent result reported. | Check a 53 listing naming PFAS, PFOA or PFOS. |
Units: µg/L is micrograms per liter, and pCi/L is picocuries per liter, a measure of radioactivity. General verdicts come from CDC home water treatment guidance, the Minnesota Department of Health, and WQA fact sheets on nitrate, arsenic and radium. BOROUX's figures come from its independent IAPMO R&T Lab test reports, dated October 28, 2025 for the main report, plus separate lead and PFAS reports. They are test-report evidence, not certification.
A carbon block filter helps with some chemical concerns, but it doesn't stand in for your utility's treatment plant. If a notice points to bacteria, nitrate or arsenic, you need something rated for that contaminant specifically. So should a low ranking worry you at all?
Does your state's rank mean your tap water is unsafe?
For most families, not by itself, and a good rank doesn't clear your tap either. A state rank describes whether community water systems met EPA requirements in one year. Your own system may have had no violation at all. Two more things to know:
- Taste and hardness aren't contamination. Hard water usually means calcium and magnesium, and a chlorine or metallic smell may be a matter of taste, not a violation. A TDS meter can't tell beneficial minerals from contaminants, so it won't settle the question.
- Private wells sit outside this data. The U.S. Geological Survey says more than 43 million people rely on private wells, and those aren't regulated under the federal Safe Drinking Water Act. If you have a well, none of these rankings describe your water. Our well water guide covers the separate testing questions.
How to check your own water
Your own system's record is what counts. Four steps get you there.
- Find your system on ECHO. EPA's ECHO drinking water dashboard lets you search for your public water system and see its violation flags and compliance history. Look for health-based violations, not monitoring and reporting ones.
- Read your annual water quality report. Every community water system must send its Consumer Confidence Report by July 1 each year. It lists what was detected and whether it met federal standards. Find yours through EPA's Consumer Confidence Report page.
- Follow any notice you receive. If your utility says to boil your water, use bottled water or stop using it, do what the notice says.
- Test for what you're worried about. A utility report describes the system, not the plumbing inside your home, so it can't see lead from your own pipes. A certified lab test can. Start with our guide to what's in your tap water, or see a home-testing option.
For another look at your utility's detection history, there's EWG's Tap Water Database. EWG reports against its own health guidelines, which differ from EPA's legal limits and aren't EPA violations. We don't use EWG's numbers in this ranking.
Where do PFAS fit?
PFAS don't change this ranking, because the available PFAS data shows what was found, not whether a system complied. In EPA's UCMR 5 data summary, a weighted estimate is that 7.8% of public water systems nationwide had an average above the limit for at least one regulated PFAS. EPA says those results "do not indicate compliance or noncompliance."
The 2024 federal PFAS rule set a limit of 4 parts per trillion for PFOA and PFOS, which is four billionths of a gram per liter. As of September 2026, EPA's May 18, 2026 proposals would give some systems until 2031 to comply and would rescind the limits for PFHxS, PFNA, HFPO-DA and the mixture Hazard Index. Follow the current status on EPA's PFAS page or read our PFAS explainer. For your family, PFAS is a testing question for your own tap, not a state score.
Full ranking: all 50 states and DC
| Rank by people | State | % of residents on a system with a violation | Rank by systems | % of systems with a violation | Community water systems | Systems with a violation | Population served | Most common rule family | Largest system's share (%) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Hawaii | 0.0 | 1 | 0.0 | 118 | 0 | 1,507,181 | None | — |
| 2 | Florida | 0.07 | 2 | 1.0 | 1,593 | 16 | 22,112,439 | Stage 2 DBP Rule | 49.8 |
| 3 | Delaware | 0.07 | 5 | 1.94 | 206 | 4 | 1,022,226 | Inorganic Chemicals | 45.8 |
| 4 | North Dakota | 0.2 | 6 | 1.97 | 305 | 6 | 706,282 | Lead and Copper Rule | 54.8 |
| 5 | Connecticut | 0.22 | 27 | 5.49 | 474 | 26 | 2,726,655 | Total Coliform Rules | 53.9 |
| 6 | Washington | 0.28 | 8 | 2.34 | 2,311 | 54 | 9,564,273 | Inorganic Chemicals | 20.0 |
| 7 | California | 0.45 | 23 | 4.98 | 2,812 | 140 | 40,104,392 | Inorganic Chemicals | 13.8 |
| 8 | Maine | 0.6 | 29 | 5.96 | 386 | 23 | 691,453 | Lead and Copper Rule | 25.5 |
| 9 | Maryland | 0.67 | 11 | 2.8 | 464 | 13 | 5,529,590 | Stage 2 DBP Rule | 42.0 |
| 10 | Iowa | 0.71 | 3 | 1.57 | 1,080 | 17 | 3,017,414 | Inorganic Chemicals | 44.8 |
| 11 | Nevada | 0.99 | 43 | 12.31 | 195 | 24 | 3,121,873 | Groundwater Rule | 61.8 |
| 12 | Virginia | 1.05 | 16 | 3.69 | 1,056 | 39 | 7,446,446 | Stage 2 DBP Rule | 24.4 |
| 13 | Colorado | 1.07 | 41 | 10.02 | 1,058 | 106 | 7,193,844 | Groundwater Rule | 24.8 |
| 14 | Rhode Island | 1.2 | 39 | 8.99 | 89 | 8 | 1,065,952 | Lead and Copper Rule | 64.1 |
| 15 | Vermont | 1.52 | 10 | 2.47 | 405 | 10 | 465,404 | Lead and Copper Rule | 87.4 |
| 16 | Wisconsin | 1.7 | 24 | 5.19 | 1,022 | 53 | 4,236,576 | Groundwater Rule | 13.4 |
| 17 | Tennessee | 1.73 | 14 | 3.14 | 446 | 14 | 7,875,875 | Stage 2 DBP Rule | 39.6 |
| 18 | South Carolina | 1.77 | 4 | 1.6 | 562 | 9 | 4,815,162 | Stage 2 DBP Rule | 60.4 |
| 19 | Kansas | 1.81 | 33 | 7.61 | 854 | 65 | 2,872,457 | Stage 2 DBP Rule | 12.7 |
| 20 | Minnesota | 1.83 | 19 | 4.34 | 968 | 42 | 4,681,564 | Radionuclides | 39.8 |
| 21 | Utah | 2.21 | 32 | 7.57 | 502 | 38 | 3,713,734 | Groundwater Rule | 48.3 |
| 22 | Montana | 2.43 | 22 | 4.86 | 803 | 39 | 790,601 | Total Coliform Rules | 25.5 |
| 23 | Illinois | 2.6 | 26 | 5.43 | 1,787 | 97 | 12,093,685 | Lead and Copper Rule | 9.1 |
| 24 | Idaho | 2.72 | 34 | 7.71 | 765 | 59 | 1,568,464 | Groundwater Rule | 34.4 |
| 25 | Michigan | 2.76 | 15 | 3.63 | 1,377 | 50 | 7,418,920 | Lead and Copper Rule | 30.9 |
| 26 | Missouri | 2.92 | 28 | 5.59 | 1,432 | 80 | 5,707,087 | Groundwater Rule | 24.0 |
| 27 | Alabama | 2.93 | 9 | 2.4 | 500 | 12 | 6,314,046 | Stage 2 DBP Rule | 23.5 |
| 28 | Indiana | 3.07 | 38 | 8.75 | 766 | 67 | 5,231,650 | Groundwater Rule | 30.5 |
| 29 | Georgia | 3.22 | 13 | 2.93 | 1,742 | 51 | 10,619,849 | Stage 2 DBP Rule | 36.5 |
| 30 | Ohio | 4.04 | 17 | 3.73 | 1,125 | 42 | 10,455,183 | Groundwater Rule | 66.2 |
| 31 | New Hampshire | 4.13 | 25 | 5.24 | 706 | 37 | 922,702 | Groundwater Rule | 32.1 |
| 32 | Kentucky | 4.14 | 37 | 8.58 | 373 | 32 | 5,054,146 | Stage 2 DBP Rule | 21.0 |
| 33 | North Carolina | 4.29 | 12 | 2.83 | 1,980 | 56 | 9,657,715 | Stage 2 DBP Rule | 28.6 |
| 34 | Nebraska | 4.51 | 21 | 4.8 | 583 | 28 | 1,707,669 | Inorganic Chemicals | 66.8 |
| 35 | Alaska | 4.89 | 46 | 21.38 | 407 | 87 | 700,160 | Groundwater Rule | 9.4 |
| 36 | Pennsylvania | 5.29 | 42 | 11.78 | 1,851 | 218 | 11,467,074 | Groundwater Rule | 15.7 |
| 37 | District of Columbia | 5.4 | 51 | 50.0 | 4 | 2 | 668,435 | Stage 2 DBP Rule | 53.5 |
| 38 | Wyoming | 5.81 | 44 | 13.93 | 323 | 45 | 534,408 | Groundwater Rule | 24.7 |
| 39 | South Dakota | 5.87 | 30 | 6.91 | 463 | 32 | 879,933 | Stage 1 DBP Rule | 54.2 |
| 40 | Arkansas | 6.0 | 35 | 8.04 | 659 | 53 | 3,062,354 | Stage 2 DBP Rule | 15.9 |
| 41 | Arizona | 6.58 | 45 | 18.96 | 749 | 142 | 7,115,496 | Groundwater Rule | 27.3 |
| 42 | New Jersey | 7.52 | 40 | 9.55 | 555 | 53 | 8,901,068 | Lead and Copper Rule | 32.4 |
| 43 | Mississippi | 9.83 | 20 | 4.55 | 1,011 | 46 | 3,205,105 | Groundwater Rule | 60.2 |
| 44 | Massachusetts | 9.99 | 18 | 3.98 | 527 | 21 | 9,973,797 | Lead and Copper Rule | 67.8 |
| 45 | New Mexico | 12.18 | 48 | 29.03 | 558 | 162 | 1,926,900 | Groundwater Rule | 23.0 |
| 46 | Texas | 13.16 | 36 | 8.42 | 4,749 | 400 | 33,188,144 | Stage 2 DBP Rule | 68.0 |
| 47 | Oklahoma | 15.14 | 47 | 22.83 | 889 | 203 | 3,653,821 | Stage 2 DBP Rule | 6.3 |
| 48 | West Virginia | 16.56 | 50 | 31.4 | 414 | 130 | 1,553,852 | Surface Water Treatment Rules | 11.6 |
| 49 | Oregon | 18.78 | 31 | 7.14 | 938 | 67 | 3,747,651 | Total Coliform Rules | 94.6 |
| 50 | Louisiana | 24.82 | 49 | 31.28 | 908 | 284 | 5,239,132 | Groundwater Rule | 25.8 |
| 51 | New York | 51.16 | 7 | 2.31 | 2,250 | 52 | 18,342,635 | Surface Water Treatment Rules | 88.1 |
Source: EPA ECHO SDWA download, file dated July 9, 2026; calendar year 2025; BOROUX analysis. "Largest system's share" is the largest single system's percentage of the state's affected residents; a high number means one utility drives the state figure. A dash means not applicable.
The rule-family labels, in plain words:
- Stage 1 or Stage 2 DBP Rule: disinfection byproducts such as TTHM and HAA5
- Inorganic Chemicals: a group of standards for contaminants such as nitrate and arsenic
- Lead and Copper Rule: tap sampling, corrosion control and service-line requirements
- Total Coliform Rules: microbial indicator requirements
- Groundwater Rule: microbial protection requirements for groundwater systems
- Surface Water Treatment Rules: plant requirements for filtration, disinfection, turbidity and covered reservoirs
- Radionuclides: radium, uranium and gross alpha/beta requirements
- None: no system had a qualifying violation
FAQ
Which state has the best tap water?
Hawaii. In this 2025 EPA analysis, 0.0% of its residents and 0.0% of its community water systems had a health-based violation. It has only 118 systems, and small states swing more. The ranking measures regulatory compliance, not taste or mineral content.
Which cities have the worst tap water?
This is a state ranking, so we don't rank cities. New York City, Portland, New Orleans, Boston and Houston move their states' figures most, as described above. To check your own city or town, use the ECHO lookup.
Does boiling water help?
Only when your utility's notice tells you to boil. CDC says boiling does not reduce lead, and Minnesota's health department says boiling makes nitrate more concentrated. For lead, look for a filter certified to NSF/ANSI 53 for lead. For nitrate, the options are reverse osmosis, anion exchange or distillation.
Where does a countertop carbon filter fit?
Once you've looked up your system and read your report, you can decide whether a filter makes sense. A gravity-fed carbon block countertop filter suits the contaminants it has evidence for: chlorine and chloramine, plus those in BOROUX's published test report, such as chloroform (the stand-in for disinfection byproducts), lead under the tested conditions, total PFAS and uranium. It doesn't replace your utility's surface water treatment, and it is not intended to filter microorganisms.
Here's what a real test looks like. BOROUX's independent lab report shows lead at pH 6.5 going from 150 to an average of 1.7 micrograms per liter over 4,000 gallons, and total PFAS from 2 to 0.01 over 400 gallons. Those are lab results, not state-scale fixes.
BOROUX Foundation Filters are WQA certified to NSF Standards: NSF/ANSI 42 for nominal particulate Class I, NSF/ANSI/CAN 372 for lead-free materials (lead content, not lead reduction), and NSF/ANSI/CAN 401 for microplastics in the 0.5 to under 1 µm size range. The certifications page shows what each covers.