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These cities face the greatest water quality challenges based on EPA contaminant data, compliance history, and infrastructure assessments. Browse by overall contamination or by specific contaminants to see if your city is affected.
Water contamination is a serious public health concern affecting millions of Americans. If your city appears on these lists, consider testing your home water and using a certified filter appropriate for your specific contaminants.
See which cities have the highest levels of each contaminant. Click any contaminant to view the top 100 most affected cities.
Cities ranked by overall water quality score, factoring in all detected contaminants, compliance history, and infrastructure. Lower scores indicate more concerns.
| Rank | City | State | Score | Grade | Top Contaminants | Population |
|---|---|---|---|---|---|---|
| #1 | Alameda | California | 44/100 | F | LeadMercury | 84,394 |
| #2 | Union City | Georgia | 44/100 | F | LeadHaloacetic Acid... | 24,877 |
| #3 | San Bernardino | California | 45/100 | F | CopperNitrite | 221,094 |
| #4 | San Marcos | California | 45/100 | F | Total Trihalome...Nitrate | 100,051 |
| #5 | Windsor | Colorado | 45/100 | F | CopperNitrite | 30,201 |
| #6 | Mishawaka | Indiana | 46/100 | F | ArsenicChromium | 51,940 |
| #7 | Bardstown | Kentucky | 46/100 | F | Haloacetic Acid...Lead | 17,535 |
| #8 | Indio | California | 47/100 | F | LeadHaloacetic Acid... | 96,735 |
| #9 | San Jose | California | 47/100 | F | Total Trihalome...Nitrate | 1,012,356 |
| #10 | Safety Harbor | Florida | 47/100 | F | Total Trihalome...Copper | 12,419 |
| #11 | Hanover Park | Illinois | 47/100 | F | Total Trihalome...Haloacetic Acid... | 41,216 |
| #12 | Cape Coral | Florida | 48/100 | F | Total Trihalome...Nitrite | 190,445 |
| #13 | Plantation | Florida | 48/100 | F | LeadCopper | 92,578 |
| #14 | Dalton | Georgia | 48/100 | F | Haloacetic Acid...Chromium | 33,119 |
| #15 | Lenexa | Kansas | 48/100 | F | Total Trihalome...Chromium | 56,572 |
| #16 | San Buenaventura | California | 49/100 | F | Haloacetic Acid...Lead | 109,996 |
| #17 | Arvada | Colorado | 49/100 | F | Haloacetic Acid...Copper | 122,991 |
| #18 | Wheat Ridge | Colorado | 49/100 | F | LeadTotal Trihalome... | 33,790 |
| #19 | Jacksonville | Florida | 49/100 | F | Total Trihalome...Nitrate | 952,495 |
| #20 | Woodland | California | 50/100 | D | Total Trihalome...Lead | 65,033 |
| #21 | Peachtree City | Georgia | 50/100 | D | Total Trihalome...Haloacetic Acid... | 38,802 |
| #22 | Hagerstown | Maryland | 50/100 | D | Total Trihalome...Copper | 42,034 |
| #23 | Nogales | Arizona | 51/100 | D | Total Trihalome...Nitrite | 22,856 |
| #24 | Durango | Colorado | 51/100 | D | Haloacetic Acid...Copper | 16,593 |
| #25 | Coral Springs | Florida | 51/100 | D | Haloacetic Acid...Lead | 131,860 |
| #26 | Parkland | Florida | 51/100 | D | LeadTotal Trihalome... | 39,147 |
| #27 | Oswego | Illinois | 51/100 | D | LeadTotal Trihalome... | 32,956 |
| #28 | Scottsdale | Arizona | 52/100 | D | Haloacetic Acid...Total Trihalome... | 244,541 |
| #29 | Santa Clara | California | 52/100 | D | Haloacetic Acid...Lead | 125,268 |
| #30 | Houma | Louisiana | 52/100 | D | NitriteTotal Trihalome... | 37,535 |
| #31 | Parker | Colorado | 53/100 | D | Haloacetic Acid...Nitrate | 56,485 |
| #32 | Belleville | Illinois | 53/100 | D | Haloacetic Acid...Total Trihalome... | 39,285 |
| #33 | Palatine | Illinois | 53/100 | D | Haloacetic Acid...Lead | 66,114 |
| #34 | Garden Grove | California | 54/100 | D | Total Trihalome...Copper | 176,920 |
| #35 | Alexandria | Louisiana | 54/100 | D | Total Trihalome...Haloacetic Acid... | 46,654 |
| #36 | Quincy | Massachusetts | 54/100 | D | LeadCopper | 101,993 |
| #37 | El Mirage | Arizona | 55/100 | C- | Total Trihalome...Copper | 32,910 |
| #38 | Palm Bay | Florida | 55/100 | C- | NitriteArsenic | 124,351 |
| #39 | Aurora | Illinois | 55/100 | C- | LeadHaloacetic Acid... | 176,880 |
| #40 | Germantown | Maryland | 55/100 | C- | Total Trihalome...Lead | 95,954 |
| #41 | Kenai | Alaska | 56/100 | C- | Total Trihalome...Lead | 8,065 |
| #42 | Paradise Valley | Arizona | 56/100 | C- | LeadTotal Trihalome... | 17,473 |
| #43 | Encinitas | California | 56/100 | C- | LeadCopper | 66,157 |
| #44 | Mission Viejo | California | 56/100 | C- | Haloacetic Acid...Nitrite | 99,786 |
| #45 | North Miami | Florida | 56/100 | C- | LeadCopper | 65,145 |
| #46 | St. Petersburg | Florida | 56/100 | C- | Haloacetic Acid...Nitrite | 255,045 |
| #47 | Baton Rouge | Louisiana | 56/100 | C- | Total Trihalome...Haloacetic Acid... | 224,800 |
| #48 | Lake Charles | Louisiana | 56/100 | C- | CopperHaloacetic Acid... | 89,012 |
| #49 | Prescott | Arizona | 57/100 | C- | CopperNitrate | 46,399 |
| #50 | Pooler | Georgia | 57/100 | C- | Total Trihalome...Haloacetic Acid... | 23,913 |
Our water quality scores (0-100) are calculated based on three factors:
Being on this list doesn't mean water is unsafe to drink, but indicates:
Click on your city in the rankings or use our search to see exactly which contaminants are present and at what levels.
Not all filters remove all contaminants. Choose a filter certified to remove the specific contaminants found in your water.
Municipal testing doesn't capture contaminants from your home plumbing. Testing your tap water directly provides the most relevant data.
Request your utility's annual Consumer Confidence Report and stay aware of any water quality advisories in your area.