What is Polychlorinated biphenyls (PCBs) and Why Does It Matter?

Polychlorinated biphenyls — better known as PCBs — are a group of man-made chemicals that were widely used in electrical equipment, industrial fluids, and building materials throughout most of the 20th century. The U.S. banned their production in 1979, but PCBs don't break down easily. They linger in soil, sediment, and water for decades. PCBs enter drinking water primarily through leaching from old industrial sites, contaminated groundwater, and aging infrastructure near former manufacturing facilities.

The health concerns around PCBs are serious and well-documented. The International Agency for Research on Cancer classifies PCBs as a known human carcinogen. Long-term exposure — even at low levels — has been linked to liver damage, immune system disruption, hormonal interference, and developmental problems in children (according to the EPA). PCBs are particularly concerning for pregnant women and young children because they can affect brain development and disrupt the endocrine system. These aren't theoretical risks. They're based on decades of research across human and animal populations.

The EPA's maximum contaminant level (MCL) for PCBs in drinking water is 0.5 parts per billion (ppb). On the surface, that sounds protective. But the Environmental Working Group (EWG) sets its health guideline far lower — at just 0.0000064 ppb — based on cancer risk modeling. That's a massive gap between what's legally allowed and what researchers consider safe for long-term consumption. Of the 21 water systems across the country that detected PCBs, 8 reported levels above the EWG health guideline. The average detected level was 0.088 ppb. One system hit the maximum of 0.5 ppb — exactly at the EPA's legal limit, but roughly 78,000 times above the EWG guideline.

Florida leads the country in PCB detections, with 9 water systems reporting the contaminant. Ohio follows with 3, and Arizona and Kentucky each show 2. Delaware rounds out the top states with 1 affected system. Florida's numbers likely reflect the state's dense mix of aging industrial corridors, legacy contamination from manufacturing sites, and the challenges of managing water quality across a large, geographically varied state. Ohio's presence on this list isn't surprising either — the state has a long industrial history, and PCB contamination near old electrical facilities and manufacturing plants remains an ongoing concern. Arizona's detections are worth watching, given the state's reliance on complex water delivery infrastructure across long distances.

The good news is that PCBs are very effectively removed by the right filtration technology. Granular activated carbon (GAC) filters and reverse osmosis (RO) systems are both proven to reduce PCB levels significantly. The EPA specifically lists activated carbon as a recommended treatment method for PCBs. A high-quality reverse osmosis system can remove up to 99% or more of PCBs from your drinking water. If you're in Florida, Ohio, Arizona, or Kentucky — or if you simply want peace of mind — checking your annual water quality report (called a Consumer Confidence Report) is a smart first step. Echo Water's reverse osmosis systems are designed to target exactly these kinds of persistent industrial contaminants, giving your family cleaner water at the tap without relying on what's legally "acceptable." Legal and safe aren't always the same thing, and with PCBs, that distinction matters.

Regulatory Standards for Polychlorinated biphenyls (PCBs)

Cities With the Highest Polychlorinated biphenyls (PCBs) Levels

States Most Affected by Polychlorinated biphenyls (PCBs)

Frequently Asked Questions

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