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These cities have significant water quality challenges based on EPA contaminant data, compliance violations, and infrastructure concerns. Residents in these areas should strongly consider using certified water filters.
If your city appears on this list, we strongly recommend using a certified water filter to protect your family's health. Pay special attention to the specific contaminants found in your city's water.
View Filter RecommendationsClick any city to see detailed water quality report including specific contaminants, violations, and recommended filters.
| Rank | City | State | Score | Grade | Population Affected |
|---|---|---|---|---|---|
| #1 | Alameda | California | 44/100 | F | 79,827 |
| #2 | Union City | Georgia | 44/100 | F | 22,329 |
| #3 | San Bernardino | California | 45/100 | F | 222,101 |
| #4 | San Marcos | California | 45/100 | F | 97,477 |
| #5 | Windsor | Colorado | 45/100 | F | 32,551 |
| #6 | Mishawaka | Indiana | 46/100 | F | 51,063 |
| #7 | Bardstown | Kentucky | 46/100 | F | 13,567 |
| #8 | Indio | California | 47/100 | F | 92,301 |
| #9 | San Jose | California | 47/100 | F | 1,013,240 |
| #10 | Safety Harbor | Florida | 47/100 | F | 17,203 |
| #11 | Hanover Park | Illinois | 47/100 | F | 38,510 |
| #12 | Cape Coral | Florida | 48/100 | F | 194,016 |
| #13 | Plantation | Florida | 48/100 | F | 94,366 |
| #14 | Dalton | Georgia | 48/100 | F | 34,417 |
| #15 | Lenexa | Kansas | 48/100 | F | 57,434 |
| #16 | San Buenaventura | California | 49/100 | F | 110,763 |
| #17 | Arvada | Colorado | 49/100 | F | 124,402 |
| #18 | Wheat Ridge | Colorado | 49/100 | F | 32,133 |
| #19 | Jacksonville | Florida | 49/100 | F | 949,611 |
| #20 | Woodland | California | 50/100 | D | 61,032 |
| #21 | Peachtree City | Georgia | 50/100 | D | 38,633 |
| #22 | Hagerstown | Maryland | 50/100 | D | 43,527 |
| #23 | Nogales | Arizona | 51/100 | D | 20,103 |
| #24 | Durango | Colorado | 51/100 | D | 19,399 |
| #25 | Coral Springs | Florida | 51/100 | D | 133,759 |
| #26 | Parkland | Florida | 51/100 | D | 34,670 |
| #27 | Oswego | Illinois | 51/100 | D | 34,485 |
| #28 | Scottsdale | Arizona | 52/100 | D | 241,361 |
| #29 | Santa Clara | California | 52/100 | D | 127,134 |
| #30 | Houma | Louisiana | 52/100 | D | 33,727 |
| #31 | Parker | Colorado | 53/100 | D | 58,512 |
| #32 | Belleville | Illinois | 53/100 | D | 41,097 |
| #33 | Palatine | Illinois | 53/100 | D | 69,350 |
| #34 | Garden Grove | California | 54/100 | D | 172,800 |
| #35 | Alexandria | Louisiana | 54/100 | D | 45,275 |
| #36 | Quincy | Massachusetts | 54/100 | D | 101,636 |
| #37 | El Mirage | Arizona | 55/100 | C- | 35,753 |
| #38 | Palm Bay | Florida | 55/100 | C- | 119,760 |
| #39 | Aurora | Illinois | 55/100 | C- | 177,564 |
| #40 | Germantown | Maryland | 55/100 | C- | 91,249 |
| #41 | Kenai | Alaska | 56/100 | C- | 7,424 |
| #42 | Paradise Valley | Arizona | 56/100 | C- | 14,502 |
| #43 | Encinitas | California | 56/100 | C- | 62,671 |
| #44 | Mission Viejo | California | 56/100 | C- | 95,638 |
| #45 | North Miami | Florida | 56/100 | C- | 62,468 |
| #46 | St. Petersburg | Florida | 56/100 | C- | 258,308 |
| #47 | Baton Rouge | Louisiana | 56/100 | C- | 227,470 |
| #48 | Lake Charles | Louisiana | 56/100 | C- | 84,872 |
| #49 | Prescott | Arizona | 57/100 | C- | 43,376 |
| #50 | Pooler | Georgia | 57/100 | C- | 25,711 |
Contaminants like lead, arsenic, nitrates, or disinfection byproducts found at levels approaching or exceeding EPA maximum limits.
Multiple or recent violations of Safe Drinking Water Act requirements, including health-based violations or failure to properly monitor.
Old pipes, outdated treatment facilities, or inadequate distribution systems that contribute to water quality degradation.
Contamination from agricultural runoff, industrial discharge, or naturally occurring minerals in the source water supply.
Click on your city above to see the specific contaminants and violations affecting your water. Understanding the exact issues is the first step to protection.
Choose a filter certified to remove the specific contaminants in your water. Not all filters remove all contaminants. Look for NSF certification for your concerns.
Municipal testing doesn't include your home plumbing. Home tests can identify lead from pipes or other issues specific to your residence.
Review your water utility's annual Consumer Confidence Report. Attend public meetings about water quality and advocate for infrastructure improvements.
Water quality varies over time, but cities commonly cited for water quality issues include Flint, Michigan (historic lead crisis), Newark, New Jersey (lead contamination), and various cities in Texas and California with elevated arsenic or PFAS levels. Check our updated rankings for the current worst-rated cities based on EPA data.
Poor water quality results from: 1) Elevated contaminant levels (lead, arsenic, PFAS, nitrates) exceeding or approaching EPA limits, 2) EPA compliance violations, 3) Aging infrastructure that introduces contaminants, 4) Inadequate treatment processes, 5) Contaminated source water from industrial or agricultural pollution.
If your city has poor water quality: 1) Install a certified water filter matched to your specific contaminants (reverse osmosis for lead/PFAS/arsenic), 2) Use only cold water for drinking and cooking, 3) Run water for 30 seconds before use, 4) Consider having your home water tested, 5) Stay informed through your utility's annual water quality report.
Bottled water can be a temporary solution but is expensive and creates plastic waste. A better long-term solution is installing a certified water filter. Reverse osmosis systems remove 95-99% of contaminants including lead, arsenic, and PFAS, and provide safe water at a fraction of the cost of bottled water over time.
Water quality differences stem from: 1) Natural geology (arsenic, radium occur naturally in some regions), 2) Industrial history (legacy contamination near factories, military bases), 3) Infrastructure age (older pipes, lead service lines), 4) Funding levels (wealthier cities invest more in water treatment), 5) Source water quality (surface water vs groundwater, upstream pollution).