Naphthalene: The Contaminant in Tap Water You Didn't Know Was Harming Your Health

Written by Craig "The Water Guy" Phillips

When you turn on your tap expecting clean, safe drinking water, the last thing you might consider is the presence of naphthalene - a chemical compound that could be silently affecting your health. This aromatic hydrocarbon, commonly known for its use in mothballs, represents one of the lesser-known but potentially significant contaminants that can infiltrate our water supply systems. Understanding naphthalene contamination is crucial for protecting your family's health and making informed decisions about your drinking water.

Understanding Naphthalene and Its Presence in Water Systems

Naphthalene is a white crystalline compound with a distinctive mothball odor that belongs to a class of chemicals known as polycyclic aromatic hydrocarbons (PAHs).
This organic compound occurs naturally in fossil fuels and is also produced synthetically for various industrial applications. While many people associate naphthalene primarily with traditional mothballs, its presence in our environment - and potentially our drinking water - extends far beyond this household use.

The compound's molecular structure makes it relatively stable in the environment, which unfortunately means it can persist in water systems for extended periods. What makes naphthalene particularly concerning as a water contaminant? Its ability to dissolve in water, though limited, is sufficient to create health risks when consumed over time. The chemical can enter groundwater through various pathways, including industrial discharge, atmospheric deposition, and leaching from contaminated soil.

Naphthalene's volatility means it can evaporate from water surfaces, but this same property can lead to inhalation exposure when contaminated water is used for showering or cooking. The compound's persistence in the environment and its potential for bioaccumulation make it a contaminant of particular concern for water quality professionals and public health officials.

Primary Sources of Naphthalene Contamination in Drinking Water

Industrial activities represent the largest source of naphthalene contamination in water systems, with coal tar production, petroleum refining, and chemical manufacturing being primary contributors.
These industrial processes release naphthalene into the environment through various pathways, including direct discharge into water bodies, atmospheric emissions that later deposit into water sources, and contamination of soil that subsequently leaches into groundwater.

Coal gasification plants and coking operations have historically been significant sources of naphthalene contamination. Many older industrial sites, particularly those involved in gas production and coal processing, may have legacy contamination that continues to affect local water sources decades after operations ceased. How does naphthalene travel from these industrial sources to your tap? The compound can migrate through soil and groundwater systems, eventually reaching municipal water supplies or private wells.

Vehicle emissions and the combustion of fossil fuels also contribute to naphthalene contamination through atmospheric deposition. When naphthalene-containing particles settle into surface water bodies like rivers and lakes used as drinking water sources, they can introduce contamination into the water treatment system. Additionally, leaking underground storage tanks, particularly those containing petroleum products, can be significant point sources of naphthalene contamination in groundwater.

Surprisingly, some household products beyond mothballs can contribute to localized naphthalene contamination. Wood preservatives, certain pesticides, and some consumer products containing coal tar derivatives may introduce naphthalene into the environment, though typically at lower concentrations than industrial sources.

Health Effects and Risks Associated with Naphthalene Exposure

Exposure to naphthalene through contaminated drinking water can lead to both acute and chronic health effects, with the severity depending on the concentration and duration of exposure.
The compound is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC), making any level of exposure a potential concern for long-term health.

Short-term exposure to higher concentrations of naphthalene can cause immediate symptoms including nausea, vomiting, diarrhea, and confusion. Some individuals may experience hemolytic anemia, a condition where red blood cells are destroyed faster than they can be produced. What makes naphthalene exposure particularly dangerous for certain populations? Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency are at significantly higher risk for severe anemia and other complications from naphthalene exposure.

Chronic exposure to lower levels of naphthalene, which is more likely through contaminated drinking water, can lead to cataracts, kidney damage, and liver dysfunction. Studies have shown that prolonged exposure may affect the nervous system, potentially causing headaches, fatigue, and cognitive difficulties. There is also concern about naphthalene's potential to disrupt endocrine function, though research in this area is ongoing.

Children and pregnant women face particular risks from naphthalene exposure. The developing nervous system is more vulnerable to chemical damage, and naphthalene exposure during pregnancy may affect fetal development. Additionally, children's higher water consumption relative to body weight increases their potential exposure levels, making contamination particularly concerning for families with young children.

Detection Methods and Regulatory Standards for Naphthalene

Detecting naphthalene in drinking water requires sophisticated analytical techniques, primarily gas chromatography-mass spectrometry (GC-MS), which can identify and quantify the compound at very low concentrations.
This analytical method is sensitive enough to detect naphthalene at the parts-per-billion level, which is necessary given the compound's potential health effects even at low concentrations.

The Environmental Protection Agency (EPA) has established a Maximum Contaminant Level Goal (MCLG) of zero for naphthalene in drinking water, reflecting the agency's determination that there is no safe level of exposure to this potential carcinogen. However, the Maximum Contaminant Level (MCL) - the legally enforceable standard - is set at 100 parts per billion (ppb). Why is there a difference between the MCLG and MCL for naphthalene? The MCL represents a practical limit that balances health protection with the technical and economic feasibility of treatment and detection.

Regular monitoring for naphthalene is required for larger public water systems, but smaller systems and private wells may not be tested routinely. This monitoring gap means that many consumers may be unaware of potential naphthalene contamination in their water supply. Water utilities must test for naphthalene as part of their synthetic organic chemical monitoring, typically every three years unless contamination is detected.

Private well owners should consider testing for naphthalene if their wells are located near industrial sites, former gas plants, or areas with known petroleum contamination. Professional water testing laboratories can perform naphthalene analysis, though the test may need to be specifically requested as it's not included in standard water quality panels.

Treatment and Prevention Strategies for Naphthalene Contamination

Several water treatment technologies can effectively remove naphthalene from drinking water, with activated carbon adsorption being the most commonly used and effective method.
Granular activated carbon (GAC) systems can achieve high removal rates for naphthalene, making them an excellent choice for both municipal treatment facilities and point-of-use home systems. The porous structure of activated carbon provides numerous binding sites for naphthalene molecules, effectively removing them from the water stream.

Advanced oxidation processes, including ozonation and UV treatment combined with hydrogen peroxide, can break down naphthalene molecules into less harmful compounds. These treatment methods are particularly effective because they actually destroy the contaminant rather than simply removing it. What factors should you consider when choosing a treatment system for naphthalene removal? The choice depends on contamination levels, water usage patterns, budget considerations, and whether other contaminants are also present.

For homeowners concerned about naphthalene contamination, point-of-use carbon filtration systems can provide effective protection. However, it's important to choose systems certified for volatile organic compound (VOC) removal and to maintain them properly with regular filter changes. Whole-house carbon systems may be warranted in areas with confirmed widespread contamination.

Prevention strategies focus on reducing naphthalene sources and protecting water supplies. This includes proper disposal of naphthalene-containing products, supporting industrial pollution control measures, and protecting groundwater sources from contamination. Communities can advocate for stronger industrial discharge controls and environmental monitoring to prevent future contamination.

Frequently Asked Questions About Naphthalene in Drinking Water

Understanding naphthalene contamination can be complex, and many people have questions about this lesser-known water contaminant.
Here are answers to the most common questions about naphthalene in drinking water.

Q: How can I tell if my water contains naphthalene?
A: Naphthalene often produces a mothball-like odor in water, but contamination can be present without any noticeable taste or smell. Professional water testing is the only reliable way to confirm naphthalene presence and concentration levels.

Q: Is boiling water effective for removing naphthalene?
A: Boiling can reduce naphthalene levels since it's somewhat volatile, but it's not a reliable treatment method. Boiling may actually concentrate other contaminants and isn't recommended as a primary treatment for naphthalene contamination.

Q: How long does naphthalene stay in the body after exposure?
A: Naphthalene is metabolized relatively quickly by the liver, with most of it eliminated from the body within 24-48 hours. However, repeated exposure through contaminated water can lead to accumulation of metabolites and ongoing health effects.

Q: Are there any natural ways to remove naphthalene from water?
A: While some natural materials like certain clays and organic matter can bind naphthalene, these methods are not reliable or practical for drinking water treatment. Certified treatment systems are recommended for effective and safe removal.

Q: Should I be concerned about naphthalene if I use municipal water?
A: Municipal water systems are required to test for and treat naphthalene contamination, but breakthrough can occur. If you live near industrial areas or notice mothball odors in your water, consider independent testing for peace of mind.

Q: What should I do if my water tests positive for naphthalene?
A: Contact your water utility immediately if you're on municipal water, or install appropriate treatment if you have a private well. Consider using bottled water for drinking and cooking until treatment is in place, and consult with a healthcare provider about potential health effects.