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

Written by Craig "The Water Guy" Phillips

Every day, millions of people turn on their taps expecting clean, safe drinking water, but lurking beneath the surface may be a dangerous contaminant that most have never heard of: perchlor. This industrial chemical, also known as perchloroethylene or tetrachloroethylene (PCE), has been quietly infiltrating water supplies across communities, posing serious health risks that many consumers remain unaware of. Understanding perchlor contamination is crucial for protecting your family's health and making informed decisions about your drinking water safety.

Understanding Perchlor: What Is This Silent Water Contaminant

Perchlor is a colorless, volatile organic compound (VOC) that has been widely used in industrial applications for decades.
Chemically known as tetrachloroethylene or perchloroethylene, this synthetic chemical belongs to a class of compounds called chlorinated solvents. The substance is highly effective as a degreasing agent and solvent, which explains its widespread industrial adoption since the 1930s.

What makes perchlor particularly concerning is its persistence in the environment: Unlike many organic compounds that break down naturally over time, perchlor can remain stable in groundwater for years or even decades. This chemical doesn't occur naturally in the environment, meaning any detection in water supplies is a direct result of human industrial activity.

The physical properties of perchlor make it especially problematic for water contamination. It's denser than water, which means it can sink through soil and accumulate in groundwater aquifers. Additionally, its volatile nature allows it to evaporate from contaminated water, potentially creating indoor air quality issues when contaminated water is used for showering, cooking, or other household activities.

Common Sources and Pathways of Perchlor Contamination

The primary source of perchlor contamination in drinking water stems from dry cleaning operations.
Approximately 85% of perchlor use in the United States has historically been attributed to the dry cleaning industry, where it serves as the main cleaning solvent. Thousands of dry cleaning facilities across the country have used perchlor for decades, and improper handling, storage, or disposal practices have led to soil and groundwater contamination at many of these sites.

Industrial manufacturing represents another significant source of perchlor contamination: Metal degreasing operations, textile processing facilities, and chemical manufacturing plants have all contributed to environmental releases. These facilities often used perchlor in large quantities, and historical disposal practices frequently involved direct discharge to the ground or into unlined lagoons.

Underground storage tanks and waste disposal sites present ongoing contamination risks. Many older facilities stored perchlor in underground tanks that were prone to leaking due to corrosion or structural failures. Similarly, hazardous waste sites where perchlor-containing materials were disposed of continue to be sources of groundwater contamination decades after their closure.

Transportation accidents and spills have also contributed to localized contamination incidents. Tank truck accidents, railroad derailments, and pipeline failures have resulted in significant perchlor releases that can impact nearby water supplies.

Health Effects and Risks Associated with Perchlor Exposure

Perchlor exposure has been linked to a wide range of serious health effects, making it a contaminant of significant concern for public health officials.
The Environmental Protection Agency (EPA) has classified perchlor as a likely human carcinogen based on extensive research showing increased cancer rates in exposed populations. Studies have specifically linked perchlor exposure to increased risks of bladder cancer, non-Hodgkin's lymphoma, and multiple myeloma.

Neurological effects represent some of the most concerning health impacts of perchlor exposure: Research has documented connections between perchlor contamination and cognitive impairment, memory problems, and mood disorders. Pregnant women exposed to perchlor face particular risks, as studies have shown associations with birth defects, developmental delays, and pregnancy complications.

Liver and kidney damage can result from both acute and chronic perchlor exposure. The chemical is metabolized primarily in the liver, where it can cause cellular damage and interfere with normal organ function. Long-term exposure has been associated with liver enzyme elevation and kidney function impairment.

Respiratory and cardiovascular effects have also been documented in populations exposed to perchlor-contaminated water. These can include breathing difficulties, chest pain, and irregular heart rhythms. Additionally, perchlor exposure may suppress immune system function, potentially increasing susceptibility to infections and other diseases.

Detection, Testing, and Monitoring of Perchlor in Water Supplies

Detecting perchlor in drinking water requires specialized laboratory testing using sophisticated analytical equipment.
The most common method for perchlor detection is gas chromatography coupled with mass spectrometry (GC-MS), which can identify and quantify the chemical at very low concentrations. This testing method is highly accurate and can detect perchlor at levels well below the EPA's maximum contaminant level.

The EPA has established a maximum contaminant level (MCL) of 5 parts per billion (ppb) for perchlor in public drinking water systems: This standard was set based on health risk assessments and the best available treatment technology. Public water systems are required to monitor for perchlor and other volatile organic compounds on a regular basis, with testing frequency determined by factors such as contamination history and potential sources in the area.

Private well owners face unique challenges regarding perchlor testing, as they are not subject to the same regulatory monitoring requirements as public water systems. How can private well owners determine if their water contains perchlor: The only reliable method is to have water samples analyzed by a certified laboratory. Testing should be conducted by homeowners who live near known contamination sources such as dry cleaning facilities, industrial sites, or hazardous waste locations.

Continuous monitoring systems are being implemented in areas with known contamination to provide real-time data on perchlor levels. These systems can alert water utilities to contamination events and help ensure rapid response to protect public health.

Treatment and Prevention Strategies for Perchlor Contamination

Several proven treatment technologies can effectively remove perchlor from contaminated drinking water.
Granular activated carbon (GAC) filtration is one of the most widely used and effective methods for perchlor removal. The carbon's porous structure adsorbs the chemical molecules, trapping them and preventing them from reaching consumers. GAC systems can achieve removal efficiencies of greater than 95% when properly designed and maintained.

Air stripping technology offers another effective treatment approach for perchlor removal: This process works by forcing air through contaminated water, causing the volatile perchlor to evaporate from the water phase into the air stream. The contaminated air is then typically treated with activated carbon to prevent atmospheric release of the chemical.

Advanced oxidation processes (AOPs) represent cutting-edge treatment technology for perchlor destruction. These systems use powerful oxidizing agents such as ozone, hydrogen peroxide, or UV light to break down perchlor molecules into harmless byproducts. AOPs offer the advantage of actually destroying the contaminant rather than simply transferring it to another medium.

Prevention strategies focus on source control and proper management of perchlor-containing materials. Modern dry cleaning facilities are transitioning to alternative cleaning solvents that pose fewer environmental risks. Proper storage, handling, and disposal of perchlor-containing materials can prevent future contamination incidents.

Groundwater remediation at contaminated sites often involves pump-and-treat systems, where contaminated groundwater is extracted, treated to remove perchlor, and either discharged or re-injected into the aquifer. In-situ treatment methods, such as injection of treatment chemicals directly into contaminated aquifers, are also being used to address perchlor plumes.

Frequently Asked Questions About Perchlor Contamination

Q: How do I know if my tap water contains perchlor?

A: The only reliable way to determine if your water contains perchlor is through laboratory testing. Contact your water utility for information about recent test results, or have your water independently tested by a certified laboratory, especially if you live near potential contamination sources like dry cleaning facilities or industrial sites.

Q: Is it safe to shower or bathe in water contaminated with perchlor?

A: Perchlor can be absorbed through the skin and inhaled when it evaporates from hot water during showering. While the primary concern is drinking contaminated water, prolonged exposure through bathing may also pose health risks. Consider installing whole-house treatment systems if your water contains perchlor above safe levels.

Q: Can boiling water remove perchlor contamination?

A: While boiling water can reduce perchlor levels due to its volatile nature, it's not a reliable treatment method and may actually increase indoor air contamination. Professional treatment systems like activated carbon filtration are much more effective and safer for removing perchlor from drinking water.

Q: What should I do if perchlor is detected in my water supply?

A: If perchlor is detected above safe levels, immediately switch to bottled water for drinking and cooking. Contact your water utility or health department for guidance, and consider installing appropriate water treatment equipment. Pregnant women and children should be especially cautious about exposure to contaminated water.

Q: How long does perchlor contamination typically last in groundwater?

A: Perchlor is highly persistent in groundwater and can remain at dangerous levels for decades without treatment. Natural breakdown processes are extremely slow, which is why active remediation efforts are typically necessary to address contamination and protect drinking water supplies.

Q: Are there any home water filters that can remove perchlor effectively?

A: Yes, activated carbon filters certified for volatile organic compound (VOC) removal can effectively reduce perchlor levels. Look for filters certified by NSF International under Standard 53 for VOC reduction. However, ensure proper maintenance and cartridge replacement according to manufacturer specifications for continued effectiveness.