Millions of people rely on tap water daily, but is it really safe? While the Environmental Protection Agency (EPA) regulates some contaminants, its standards often exceed the recommended safe levels established by researchers at the Environmental Working Group (EWG). 

Even after treatment, water quality varies widely by location, leaving many unaware of potential risks.

Water quality standards and testing methods vary by state, so there is no definitive ranking of states with the most unsafe drinking water. 

Above all, we strive to remain objective while presenting factual information sourced from the EPA, EWG, and various studies. This particular list highlights states with the highest number of water quality violations in public water systems based on EPA data.

Regardless of your state’s rank, taking proactive steps to protect yourself from contaminants like chemicals and metals in your water is vital. Explore our  tap water database for reports on your local water quality and personalized recommendations to ensure safe, trusted water.

104,677 acute violations

718,049 health-based violations

• Groundwater in Oregon has been polluted with nitrates for decades. Morrow County residents recently filed a lawsuit against the Port of Morrow and businesses for dumping nitrate levels up to 4x the EPA’s limit into drinking water.

• Southern Oregon's water system was found to have unsafe arsenic levels this year. Further research showed that the region has struggled with arsenic contamination for the last two decades. 

• Over 300 utilities in Oregon serve nearly 4 million people with water containing harmful levels of total trihalomethanes (TTHM), haloacetic acids (HAA5), and nitrates.

903,930 acute violations 

1,821,238 health-based violations

• A 2024 EWG report ranks Pennsylvania among the top 5 states with the most contaminated drinking water systems. 

• Of the water systems tested this year, 19% contain PFAS levels above new EPA standards.  

• The USGS tested Pennsylvania rivers and streams – sources of drinking water for residents of Philadelphia and surrounding counties – for PFAS in 2023, and found 76% contained one or more types of the chemical. 

• Pennsylvania has approximately 261,023 lead pipes that need to be replaced under new federal mandates.

Over 1,300 water supplies serving 11 million residents have concerning levels of TTHM, bromodichloromethane, and chloroform in their water.

196,838 acute violations 

1,457,187 health-based violations

• Massachusetts ranks among the top states for contaminated water, with 439 systems affected.

• Springfield residents are at risk of HAA5 exposure after samples taken in September showed concentrations of HAA5 that exceeded the federal limit. 

• Massachusetts has approximately 132,627 lead pipes in use.

Over 6 million residents are using tap water with concerning levels of TTHM, HAA5, and chloroform.

435,166 acute violations 

806,526 health-based violations

• Durant residents received a notice from their Public Works department warning that levels of HAA5 in their water supply exceeded the EPA’s Maximum Contaminant Levels. 

• Oklahoma lawmakers are now taking significant steps to address elevated levels of chromium 6 in their water supplies to protect residents from the carcinogen. 

• Nearly 800 public water utilities are supplying over 3 million residents with water containing concerning levels of TTHM, chloroform, and nitrates.

57,422 acute violations 

495,576 health-based violations

• Paden City's water is still contaminated with tetrachloroethylene, exposing residents to severe health risks. Despite Superfund designation in 2022, cleanup plans remain vague, and past contamination levels are unknown.

• Ritchie County officials are planning to build a new community water system after water samples showed high levels of arsenic and lead. 

• Over 1.5 million residents with water containing elevated levels of TTHM, HAA5, and nitrates.

1,727,204 acute violations 

561,075 health-based violations

• The EPA has ordered the U.S. Air Force and Arizona National Guard to address rising PFAS contamination in Tucson’s groundwater. These “forever chemicals” have reached dangerous concentrations near the Tucson International Airport at the National Guard base and at a property owned by the U.S. Air Force.

• The Arizona Department of Environmental Quality estimates that nearly 30% of Arizona's water systems fail to meet new limits for arsenic. 

• Phoenix is one of the largest cities with the highest levels of chromium 6 in their water systems. 

• Over 6 million Arizona residents are affected by water contamination, with up to 670 utilities reporting elevated nitrates, arsenic, and chromium 6.

1,617,783 acute violations 

451,556 health-based violations

• Maryland officials detected high levels of PFAS at 10 schools. Given the dangers of PFAS exposure, the Maryland Department of the Environment advised against consumption.

• EPA reports indicate that the six states within the Chesapeake Bay watershed, one of the sources of drinking water in Maryland, are unlikely to meet pollution reduction goals by the 2025 Chesapeake Bay Watershed Agreement. 

• Elevated levels of TTHMs found in 379 water systems, impacting over 5 million residents.

319,056 acute violations 

1,598,546 health-based violations

• A study by the Water Collaborative of Greater New Orleans found 88% of homes tested had lead, with some exceeding the EPA’s action level. 

• Louisiana has approximately 140,762 lead pipes in use. 

• Shreveport officials detected historic levels of manganese in their water supply. 

• Over 900 systems are supplying nearly 5 million people with water containing high levels of TTHMs, HAA5, and dichloroacetic acid.

1,279,034 acute violations 

2,807,128 health-based violations

• 56% of schools in New Jersey had water supplies containing lead beyond the recommended maximum limit. 

• The New Jersey Department of Environmental Protection announced a $14 million resolution of a natural resource damages lawsuit against two companies for contaminating groundwater with TCE, which shut down drinking water wells and tainted aquifers.

• New Jersey has the most highly contaminated drinking water system, with 556 systems. 

• There are approximately 294,554 active lead pipes that need to be replaced.

• At least 379 water systems, serving more than 5 million residents, have detected elevated levels of TTHMs in their supply.

365,865 acute violations 

10,182,249 health-based violations

• A $1.25 million fine was issued after a water company and three municipalities were found supplying water contaminated with HAA5s, which are linked to cancer and birth defects.

• Syracuse announced the EPA–mandated lead monitoring found extraordinarily high levels of lead in local drinking water, with levels up to four times higher than the EPA’s lead action level. 

• New York had approximately 299,629 active lead pipes that need to be replaced.

• Over 20 million people are exposed to tap water containing TTHMs, HAA5, and arsenic at concentrations that exceed EWG Health Guidelines.

Bottled water might seem like an easy fix for contaminated tap water, but the reality is that oftentimes bottled water is just as dirty as tap. Bottled water is regulated by the FDA, and their water quality standards match those of the EPA's for public tap water. In many cases, bottled water is simply tap water repackaged for sale.

Beyond that, plastic bottles can leach microplastics into the water, rendering it an ineffective alternative for clean drinking water. Learn more about the hidden risks of bottled water here.

Although water standards vary from state to state, the most reliable way to ensure your water is clean and safe is with a powerful filtration system. Clearly Filtered is proven to remove up to 99.99% of 365+ contaminants, protecting your health and providing peace of mind. Explore our lab test results and upgrade your water today.