What is Phenanthrene and Why Does It Matter?

Phenanthrene is a polycyclic aromatic hydrocarbon, or PAH — a family of chemicals formed when organic materials like coal, oil, and wood burn incompletely. It enters drinking water primarily through industrial discharge, stormwater runoff, and the breakdown of asphalt and coal tar in aging water infrastructure. Power plants, vehicle exhaust, and manufacturing facilities are among the most common sources. When rain washes over roads and industrial sites, it carries phenanthrene into rivers, reservoirs, and groundwater — the same sources many utilities draw from.

Currently, 40 water systems across the U.S. have detected phenanthrene in their supplies. The average level measured is 0.143 parts per billion (ppb), but the highest recorded amount reached 3.92 ppb — more than 27 times that average. That wide gap between the typical and peak levels matters. It tells you that while most detections are low, some systems are seeing significantly higher concentrations. The good news: none of the 40 systems currently exceed established health guidelines.

That said, "below the guideline" doesn't always mean "without risk." Phenanthrene belongs to the PAH family, which the EPA classifies as possible human carcinogens. Long-term exposure to PAHs — even at low levels — has been linked to increased cancer risk, particularly kidney and skin cancers, according to the Agency for Toxic Substances and Disease Registry (ATSDR). Animal studies show PAH exposure can also disrupt hormone function and harm the immune system. Children and pregnant women are generally considered more vulnerable to these effects. Short-term exposure at very low levels, like the averages detected here, is not associated with acute health symptoms for most people.

The EPA has not set a specific maximum contaminant level (MCL) for phenanthrene on its own. Instead, it regulates PAHs as a group under broader water quality guidelines. The Environmental Working Group (EWG) applies a more precautionary standard, recommending that PAH levels stay as low as technically achievable given their cancer-causing potential. The absence of a strict federal limit for phenanthrene individually means utilities aren't legally required to reduce it, even when it's detected. That regulatory gap is worth knowing about, especially for households with young children or immunocompromised family members.

Geographically, New Jersey accounts for 38 of the 40 systems where phenanthrene has been found — a striking concentration. Texas accounts for the remaining 2. New Jersey's numbers make sense in context. The state has one of the highest densities of Superfund sites in the country, along with heavy industrial history, aging water infrastructure, and significant urban runoff. PAHs like phenanthrene tend to accumulate in areas with long industrial footprints, and New Jersey fits that profile. If you live in New Jersey — particularly near older urban centers or industrial corridors — this is a contaminant worth paying attention to.

Fortunately, phenanthrene is effectively removed by several common filtration methods. Activated carbon filtration is one of the most reliable options. It works by attracting and trapping organic compounds like PAHs as water passes through. Granular activated carbon (GAC) filters, commonly found in under-sink systems and whole-house filters, can significantly reduce phenanthrene levels. Reverse osmosis (RO) systems go a step further, pushing water through a semi-permeable membrane that blocks a wide range of contaminants — including PAHs. An RO system combined with a carbon pre-filter offers especially strong protection. Echo Water's filtration systems use both activated carbon and reverse osmosis stages, which makes them well-suited for households concerned about PAH exposure. If you're in New Jersey or another area where phenanthrene has been detected, checking your local water quality report and pairing that information with a quality home filter is one of the most practical steps you can take.

Regulatory Standards for Phenanthrene

Cities With the Highest Phenanthrene Levels

States Most Affected by Phenanthrene

Frequently Asked Questions

Related Contaminant Guides