What is Ethylbenzene* and Why Does It Matter?

Ethylbenzene is a colorless, flammable liquid with a sweet, gasoline-like smell. It's a natural component of crude oil and coal tar, and it's widely used in manufacturing styrene — the building block of polystyrene plastics. Most ethylbenzene in drinking water comes from industrial discharge, gasoline spills, and leaking underground fuel storage tanks. When fuel leaks into soil, ethylbenzene can travel downward and reach groundwater sources that supply municipal water systems.

Across the U.S., ethylbenzene has been detected in 138 water systems. The average level found is 0.363 parts per billion (ppb), but some systems have recorded concentrations as high as 10.0 ppb. That upper end is worth paying attention to. Short-term exposure to high levels of ethylbenzene has been linked to eye and throat irritation, dizziness, and headaches. Long-term exposure at elevated levels is more concerning. Animal studies show it can damage the kidneys and liver over time, and the EPA classifies ethylbenzene as a possible human carcinogen (cancer-causing agent) based on evidence from those animal studies. The International Agency for Research on Cancer (IARC) places it in Group 2B — meaning it's "possibly carcinogenic to humans."

The EPA has set the Maximum Contaminant Level (MCL) for ethylbenzene at 700 ppb — a limit designed primarily to prevent acute, short-term health effects. That number may sound reassuring, and the good news is that none of the 138 systems where ethylbenzene was detected exceeded that legal limit. However, the EPA's legal limit and what's actually safe over a lifetime of drinking aren't always the same thing. The Environmental Working Group (EWG) recommends a much more cautious health guideline based on long-term cancer risk. When regulatory standards haven't been updated in decades, they often don't reflect the latest science on low-level, chronic exposure — which is exactly the case with ethylbenzene.

Geographically, Texas accounts for the largest share of detections by far — 91 of the 138 affected systems. That concentration isn't surprising. Texas has one of the largest petrochemical industries in the country, with extensive oil refining, fuel storage, and pipeline infrastructure. Iowa comes in second with 14 systems, followed by Pennsylvania with 7. Both states have significant agricultural and industrial activity, along with aging underground fuel storage infrastructure that can leak over time. Mississippi and New York each reported 3 affected systems. The pattern here is clear: ethylbenzene tends to show up where oil, gas, and industrial activity intersect with groundwater sources.

The most effective way to remove ethylbenzene from drinking water is activated carbon filtration. Granular activated carbon (GAC) and solid block carbon filters both perform well against volatile organic compounds (VOCs) like ethylbenzene — these are carbon-based chemicals that evaporate easily and can contaminate both water and air. Reverse osmosis (RO) systems also remove ethylbenzene effectively and provide broad protection against a wide range of contaminants at once. If you live in Texas, Iowa, Pennsylvania, or another area with known petrochemical or fuel storage activity near your water source, a whole-home or under-sink filtration system is a smart precaution. Echo Water's reverse osmosis systems are certified to remove VOCs including ethylbenzene, giving you cleaner water straight from the tap. The first step is always knowing what's in your water — pulling your annual Consumer Confidence Report (CCR) from your utility is free and tells you exactly what has been detected in your local supply.

Regulatory Standards for Ethylbenzene*

Cities With the Highest Ethylbenzene* Levels

States Most Affected by Ethylbenzene*

Frequently Asked Questions

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