Naphthalene in Drinking Water
Found in 82 water systems • vocs
Updated September 2026 • Data from EWG & EPA
What is Naphthalene and Why Does It Matter?
NAPHTHALENE IN YOUR TAP WATER: WHAT YOU NEED TO KNOW
What Is Naphthalene and How Does It Get Into Your Water?
Naphthalene is a chemical compound made of two connected benzene rings. You've probably smelled it before — it's the main ingredient in mothballs and some types of air fresheners. In nature, naphthalene forms when coal and oil break down. It also comes from human activities like coal tar production, asphalt manufacturing, and creosote wood treatment.
This chemical enters water supplies through several routes. Coal tar used to seal and repair roads leaches naphthalene into groundwater over time. Landfills and industrial sites containing coal tar or creosote-treated wood can contaminate nearby wells. In some cases, aging water pipes with coal tar linings release naphthalene directly into drinking water. Atmospheric deposition — naphthalene falling from the air as pollution settles — also contributes to surface water contamination.
Health Effects and Exposure Risks
The EPA has not set a drinking water standard for naphthalene, which means there's no federal limit on how much can be in your tap water. However, the Environmental Working Group (EWG) established a health guideline of 0.2 parts per billion (ppb) based on cancer risk research. This is important: it's lower than what the EPA requires for other similar chemicals, reflecting growing evidence of naphthalene's potential health effects.
At high exposure levels, naphthalene can damage the eyes, skin, and respiratory system. Animal studies show that chronic exposure may affect the liver and kidneys. The primary health concern for drinking water exposure is cancer risk — the International Agency for Research on Cancer (IARC) classifies naphthalene as a possible human carcinogen. Most people exposed through drinking water face low risk, but vulnerable populations like pregnant women, young children, and people with existing respiratory conditions warrant extra caution.
Current Regulations and Guidelines
Here's where things get complicated. The EPA has not established a maximum contaminant level (MCL) for naphthalene in drinking water. This doesn't mean it's safe — it means the EPA hasn't acted on it yet. The EWG's 0.2 ppb guideline is significantly stricter than what most water systems are required to monitor.
Looking at the data, naphthalene appears in 82 water systems across the United States, with an average concentration of 0.551 ppb. While no systems tested above the EWG guideline, many are approaching it. The maximum detected level was 11.4 ppb — more than 57 times higher than the EWG recommendation. This gap between current regulations and emerging health evidence is why staying informed matters.
Geographic Hotspots and Why They Exist
Arkansas leads the nation with naphthalene detection in 36 water systems, followed by Wisconsin with 9 systems. Texas, Iowa, and New Jersey each report 4 affected systems. This geographic pattern reflects the location of coal tar-related industries and aging water infrastructure.
Arkansas's high detection rate likely stems from coal tar production history and coal-dependent power generation in the region. Wisconsin's contamination correlates with industrial manufacturing zones and older water distribution systems with coal tar-lined pipes. These states share another common factor: older infrastructure that was sealed with coal tar decades ago but is now aging and breaking down.
Removal Methods and What You Can Do
Activated carbon filters effectively remove naphthalene from drinking water. Reverse osmosis systems eliminate 99.9% of naphthalene and other similar organic compounds. Granular activated carbon (GAC) filters, commonly used in pitcher and under-sink systems, reduce naphthalene to below detection levels when properly maintained.
If you live in Arkansas, Wisconsin, or other affected areas, consider testing your tap water through Echo Water's testing service. A whole-home reverse osmosis system provides comprehensive protection, while point-of-use filters work well for drinking and cooking water. Even if your water tests below the EWG guideline, filtration adds an extra layer of protection for your family's health.
Regulatory Standards for Naphthalene
| Standard | Level | Notes |
|---|---|---|
| Average Detected Level | 0.55 ppb | Across all tested systems |
| Highest Detected Level | 11.40 ppb | Worst-case system |
Cities With the Highest Naphthalene Levels
| # | City | Detected Level | People Served |
|---|---|---|---|
| 1 | Bingen, WA | 11.40 ppb | 0 |
| 2 | Quincy, IL | 5 ppb | 5,755 |
| 3 | Manly, IA | 3.35 ppb | 0 |
| 4 | Honaker, VA | 2.30 ppb | 2,250 |
| 5 | Lebanon, VA | 2.30 ppb | 375 |
| 6 | Lebanon, VA | 2.30 ppb | 125 |
| 7 | Massena, IA | 1.80 ppb | 364 |
| 8 | Spring Green, WI | 1.50 ppb | 300 |
| 9 | La Valle, WI | 1.25 ppb | 0 |
| 10 | Kelley, IA | 1 ppb | 304 |
| 11 | Lubbock, TX | 0.99 ppb | 29 |
| 12 | Pittsford, NJ | 0.94 ppb | 200 |
| 13 | Hampstead, MD | 0.90 ppb | 0 |
| 14 | New London, WI | 0.81 ppb | 71 |
| 15 | Unity, WI | 0.81 ppb | 32 |
States Most Affected by Naphthalene
How to Remove Naphthalene From Your Water
Naphthalene is effectively adsorbed by activated carbon due to its polycyclic aromatic hydrocarbon structure; quality pitcher filters with proper carbon can achieve meaningful reduction.
Standard pitcher filters and carbon block filters can provide some reduction of Naphthalene, though effectiveness varies by brand and flow rate. For maximum protection, a certified RO system is recommended.
While activated carbon works well for naphthalene, basic pitcher filters need adequate contact time and sufficiently thick carbon beds; reverse osmosis provides near-complete removal but is slower.
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Shop Hydrogen FlaskFrequently Asked Questions
Is Naphthalene in my drinking water?
Naphthalene was detected in 82 water systems across the US. Check your city's water quality report to see if it affects your water supply.
What are the health effects of Naphthalene in water?
Naphthalene has been associated with various health concerns at elevated levels. The EWG has set health guidelines that are typically stricter than EPA legal limits.
Which city has the most Naphthalene in its water?
Based on our analysis, Bingen, WA has the highest detected levels of Naphthalene in its water supply.
How do I remove Naphthalene from my water?
Reverse osmosis (RO) systems are generally the most effective at removing this contaminant. Check the filtration recommendations section for specific guidance.
Related Contaminant Guides
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
