Volatile organic compounds (VOCs) are a group of carbon-based chemicals that can contaminate drinking water through industrial activities, fuel spills, household products, and environmental pollution. If you're wondering what are VOCs in water, the answer depends on the specific chemical present, where it came from, and how it entered your water supply.
Many VOCs are commonly associated with gasoline, solvents, paints, adhesives, pesticides, and manufacturing processes. While some VOCs naturally evaporate into the air, others can migrate through soil and contaminate groundwater, private wells, and even the source water used by municipal drinking water systems. The U.S. Environmental Protection Agency (EPA) regulates specific VOC contaminants in public drinking water, but not every VOC is regulated under the Safe Drinking Water Act.
In this guide, you'll learn what volatile organic compounds are, how VOCs get into water, the most common VOCs found in drinking water, potential health concerns, how to test your water, and the most effective methods for removing VOCs from drinking water.
What are Volatile Organic Compounds?Volatile organic compounds (VOCs) are organic chemicals that evaporate easily at normal temperatures because they have a relatively high vapor pressure. Although they readily become gases in the air, VOCs can also dissolve in water and contaminate groundwater, lakes, rivers, and drinking water supplies.
Many volatile organic compounds are human-made chemicals used in industrial manufacturing, petroleum products, dry cleaning, paints, adhesives, cleaning products, and pesticides. Others occur naturally in small amounts through biological processes. Not every VOC is considered hazardous, and not every VOC found in the environment is regulated in drinking water.
It's also important to distinguish between airborne VOC exposure and VOCs in drinking water. Indoor air concerns often focus on emissions from building materials and household products, while drinking water contamination typically results from chemicals entering groundwater or source water through spills, leaks, improper disposal, or industrial activities.
Where do VOCs in Water Come From?VOCs can enter drinking water from a variety of residential, commercial, industrial, and environmental sources. Once these chemicals reach the soil, they may migrate into groundwater, affecting both private wells and the water sources used by municipal treatment facilities.
Household Sources
Common household products can contain volatile organic compounds, including:
- Paints and paint thinners
- Adhesives
- Cleaning solvents
- Automotive fluids
- Pesticides and herbicides
- Fuel stored for lawn equipment
Using these products does not automatically contaminate drinking water. However, improper disposal, accidental spills, or leaking containers can contribute to groundwater contamination over time.
Commercial and Industrial Sources
Commercial facilities and industrial operations are among the largest contributors to VOC contamination. Potential sources include:
- Manufacturing plants
- Dry cleaning facilities
- Chemical storage sites
- Industrial degreasers
- Petroleum processing
- Landfills
Leaks, spills, and improper waste disposal can allow VOCs to move through soil into underground aquifers.
Fuel and Petroleum Products
Gasoline, diesel fuel, heating oil, and other petroleum products contain several volatile organic compounds. Underground storage tank leaks, pipeline failures, and fuel spills are common pathways for these chemicals to enter groundwater.
Water Treatment Byproducts
Not all VOCs originate from pollution. Certain compounds, including total trihalomethanes (TTHMs), can form during municipal water treatment when disinfectants such as chlorine react with naturally occurring organic material in source water. These compounds are monitored separately from industrial VOC contaminants and are regulated by the EPA.
Common Products and Materials That Release VOCsMany everyday products contain volatile organic compounds, including:
- Gasoline and diesel fuel
- Paints and paint removers
- Adhesives and sealants
- Cleaning products
- Dry-cleaning chemicals
- Pesticides and herbicides
- Permanent markers
- Disinfectants
- Building materials and finishes
- Industrial solvents
The presence of VOCs in these products does not necessarily mean your drinking water is contaminated. Problems generally occur when chemicals are spilled, improperly disposed of, or repeatedly released into the environment, allowing them to reach groundwater or other drinking water sources.
How VOCs Enter Wells and Municipal Water SuppliesUnderstanding how VOCs get into water helps explain why contamination can affect both private wells and public water systems.
The process often follows a simple path:
- VOC-containing chemicals are spilled, leaked, or improperly disposed of.
- The chemicals move through soil after rainfall or groundwater recharge.
- They reach underground aquifers or surface water sources.
- Private wells or municipal utilities draw water from these sources.
- Without effective treatment, VOCs may remain in drinking water.
Private wells can be especially vulnerable because they often draw directly from groundwater and are not routinely monitored by a public utility. Municipal systems regularly test for regulated contaminants, but source water can still contain VOCs before treatment, and certain disinfection byproducts may form during the treatment process.
Common VOCs Found in Drinking WaterSeveral common VOCs in water are routinely monitored because of their potential impact on drinking water quality. The EPA regulates more than 20 volatile organic compounds in public drinking water.
Benzene
Benzene is commonly associated with gasoline and petroleum products. It can enter groundwater through fuel spills, leaking underground storage tanks, and industrial discharges. Because of its potential health concerns, benzene is regulated in public drinking water supplies.
Tetrachloroethylene (PCE)
Also known as perchloroethylene, PCE has long been used in dry cleaning and metal degreasing. Improper disposal or leaks from commercial facilities can contaminate groundwater and nearby wells.
Trichloroethylene (TCE)
TCE is an industrial solvent used for cleaning metal parts and manufacturing. Like PCE, it may enter groundwater through industrial releases or historical contamination at manufacturing sites.
Methyl Tertiary Butyl Ether (MTBE)
MTBE was widely added to gasoline to improve combustion efficiency. Although its use has declined, historic fuel leaks continue to affect groundwater in some areas.
Vinyl Chloride
Vinyl chloride is primarily associated with PVC manufacturing but can also form as other chlorinated solvents break down in groundwater. Because of its potential health risks, it is one of the VOCs most closely monitored in drinking water.
Total Trihalomethanes (TTHMs)
Unlike industrial VOCs, total trihalomethanes are a group of disinfection byproducts that form when chlorine reacts with naturally occurring organic matter during water treatment. The EPA regulates total trihalomethanes as a group because elevated concentrations may indicate treatment-related water quality concerns.
Vinyl Chloride in Drinking Water
Vinyl chloride is a volatile organic compound used primarily in the production of polyvinyl chloride (PVC), a plastic found in products such as pipes, flooring, and packaging materials. While vinyl chloride itself is not typically added to drinking water, it can enter groundwater through industrial releases, improper chemical disposal, or as other chlorinated solvents break down over time.
The EPA regulates vinyl chloride in public drinking water because long-term exposure above established limits may increase health risks. If laboratory testing confirms vinyl chloride contamination, selecting a treatment system that has been certified for the specific contaminant is important. Because treatment effectiveness varies by system design and contaminant concentration, homeowners with confirmed contamination should consult a qualified water treatment professional before choosing a filtration solution.
VOCs can affect both private wells and municipal water supplies, but the level of risk depends on the water source and surrounding environment rather than the type of water system alone.
Private Wells
Private wells are generally more vulnerable because they draw directly from groundwater and are not regulated under the Safe Drinking Water Act. If your property is located near fuel storage tanks, manufacturing facilities, dry cleaners, landfills, agricultural operations, or areas with a history of chemical spills, your well may have a greater risk of VOC contamination.
Since private wells are not routinely monitored, laboratory testing is the most reliable way to determine whether VOCs are present.
Municipal Water
Public water systems are required to monitor regulated VOC contaminants and publish annual Consumer Confidence Reports (CCRs) summarizing water quality results. Municipal treatment significantly reduces many contaminants before water reaches consumers, although some regulated disinfection byproducts, such as total trihalomethanes, can form during the treatment process.
Reviewing your local Consumer Confidence Report can help you understand which contaminants have been detected in your public water supply and whether additional point-of-use treatment may be beneficial.
Health Risks of VOCs in Drinking WaterNot all volatile organic compounds present the same level of risk. Potential health effects depend on several factors, including the specific compound, its concentration, the route of exposure, and how long exposure continues.
Some VOCs have little documented impact at the concentrations typically found in drinking water, while others are more closely monitored because of their potential health effects. For this reason, it is important to evaluate each contaminant individually rather than treating all VOCs as equally hazardous.
Potential VOC health effects vary by compound but may include:
- Liver or kidney effects from long-term exposure to certain solvents
- Nervous system effects associated with specific chemicals
- Increased cancer risk for certain regulated VOCs after prolonged exposure
- Taste or odor concerns in drinking water
This information is intended for educational purposes only and should not be considered medical advice. If testing identifies elevated VOC concentrations, consult your local health department or healthcare provider if you have concerns about potential exposure.
How to Test Water for VOCsIf you suspect VOC contamination, the most reliable way to identify the specific chemicals present is through laboratory analysis. Unlike contaminants such as hardness or chlorine, VOCs generally cannot be confirmed through simple test strips or by taste, odor, or appearance alone.
Homeowners should consider how to test water for VOCs when:
- A fuel or chemical spill occurs nearby
- A private well is located close to industrial or commercial property
- A nearby landfill or dry-cleaning facility has reported contamination
- Your water utility issues a drinking water advisory
- You notice unexplained water quality concerns and want laboratory confirmation
A typical testing process includes:
- Select a certified laboratory that offers VOC analysis.
- Collect the water sample according to the laboratory's instructions.
- Submit the sample within the required timeframe.
- Review the laboratory report to identify any detected contaminants and their concentrations.
Because VOCs can evaporate easily, proper sample collection is essential for obtaining accurate results.
How to Remove VOCs from Drinking WaterOnce testing identifies the specific contaminant, you can choose the most appropriate treatment method. Since different VOCs behave differently, no single filtration technology is ideal for every situation.
Activated Carbon Filters
Activated carbon is one of the most common treatment methods for reducing VOCs in residential drinking water. Carbon works through adsorption, attracting many organic chemicals to the surface of the carbon media as water passes through the filter.
The effectiveness of activated carbon depends on several factors, including:
- The specific VOC being treated
- Carbon media type
- Contact time
- Water chemistry
- Flow rate
- Proper filter maintenance
Because filter capacity is limited, replacement cartridges should be changed according to the manufacturer's recommendations.
Reverse Osmosis Systems
Reverse osmosis systems may also reduce certain VOCs as part of a complete treatment system. Most residential reverse osmosis systems reduce many VOCs primarily because they include activated carbon prefilters and postfilters. The RO membrane may provide additional reduction for some compounds, but carbon typically performs most of the VOC removal.
RO systems are often selected when homeowners want broader contaminant reduction beyond VOCs, including dissolved solids, nitrates, heavy metals, and other regulated contaminants.
Whole-House Treatment
If contamination affects all household water uses rather than only drinking water, a point-of-entry (whole-house) treatment system may be appropriate. In some cases, granular activated carbon systems or aeration systems are used to reduce VOC concentrations before water enters the home's plumbing.
Aeration is generally most effective for highly volatile compounds that readily transfer from water into air and is often followed by activated carbon to capture any remaining contaminants.
The best treatment approach should always be based on laboratory test results rather than assumptions about which contaminants may be present.
Learn more: Lab water tests vs at-home water test kits
Choosing the right VOC Water Treatment
Choosing the right treatment system begins with identifying exactly which VOCs are present and at what concentration. Water testing provides the information needed to compare certified treatment options and determine whether point-of-use or whole-house filtration is the better solution.
For many homeowners, an under-sink treatment system provides effective drinking water protection when contamination is limited to potable water. If contamination affects the entire household or multiple water uses, a whole-house system may provide more comprehensive treatment.
Before purchasing a filtration system, consider:
- Which contaminants have been identified
- Certified contaminant reduction claims
- System capacity
- Filter replacement requirements
- Ongoing maintenance needs
Selecting a system based on verified water test results helps ensure the treatment solution matches your home's specific water quality concerns.
Does Boiling Water Remove VOCs?
Unlike bacteria, boiling water is generally not recommended as a method for removing VOCs. Because many VOCs evaporate readily, boiling may release them into the surrounding air and can even increase the concentration of less volatile contaminants as water evaporates. Proper filtration or aeration is a safer and more effective solution.
Learn more: Activated carbon filters 101
Final Thoughts
Volatile organic compounds can enter drinking water through a variety of environmental and human-made sources, but not every VOC poses the same level of concern. Understanding what are VOCs in water, how VOCs get into water, and how to test for contamination allows homeowners to make informed treatment decisions.
The best approach is simple: identify the contaminant through laboratory testing, choose a treatment system certified for the compounds present, maintain the system according to the manufacturer's recommendations, and retest your water periodically to verify continued performance. Whether you rely on a private well or municipal water, taking these steps can help ensure your drinking water continues to meet your household's needs.
Learn more: What is a reverse osmosis system?
If you have any additional questions, please do not hesitate to contact us.
Comments
Really thorough guide on VOCs. One critical point for anyone selecting carbon filters specifically for VOC removal: the carbon source material matters enormously for different VOC types.
For low-molecular-weight VOCs like benzene, toluene, and vinyl chloride (molecular diameter 0.3-0.6 nm), coconut shell activated carbon with high micropore volume is the clear winner. Coconut shell carbon typically has iodine numbers of 1000-1200 mg/g and micropore volume of 0.8-1.2 cm³/g — that dense micropore structure creates much stronger adsorption forces for small VOC molecules compared to coal-based carbon (iodine 600-900, micropore 0.4-0.7 cm³/g).
However, for larger VOCs like MTBE (molecular diameter ~0.6 nm) or certain pesticide residues, you actually need some mesopore volume (2-50 nm) in the carbon. Coal-based carbon has a broader pore size distribution that can handle these larger molecules better.
The article makes an excellent point about filter lifespan — VOCs exhausting carbon 33% faster is spot on. In industrial settings, we use differential TOC (total organic carbon) monitoring between inlet and outlet as an early warning. When the TOC removal efficiency drops below 60% of initial performance, it’s time to replace. For homeowners without TOC monitors, a simple rule: if you notice any return of chemical taste or odor, replace immediately — the carbon is likely exhausted for VOCs even if it still removes chlorine.
Also worth noting: carbon with ash content below 3% (typical of quality coconut shell carbon) performs better for VOC adsorption because mineral ash occupies pore space that could otherwise capture VOC molecules.