Volatile organic compounds (VOCs)

At a glance: Volatile organic compounds (VOCs) are industrial and fuel chemicals, such as benzene, TCE and PCE, that dissolve in water and evaporate easily. Several are linked to cancer and liver problems, and EPA limits benzene, TCE and PCE to 5 µg/L each. They are rare above health limits in private wells but serious where they occur, usually near a gas station, dry cleaner, landfill or industrial site. Because you breathe them in the shower, a well with VOCs usually calls for whole-house carbon, not just a kitchen filter.

City water is monitored for regulated VOCs, so most city customers can rely on the annual water quality report.

What it is and where it comes from

VOCs are a large group of chemicals that, in the words of Wisconsin’s health department, “easily evaporate into the air.” They are found in fuels, solvents, paints, glues and cleaning products.

EPA’s health table gives the typical drinking water sources for the best-known ones:

Compound	Typical source (EPA)
Benzene	Factory discharge; leaching from gas storage tanks
Trichloroethylene (TCE)	Metal degreasing sites and other factories
Tetrachloroethylene (PCE)	Factories and dry cleaners
Vinyl chloride	Leaching from PVC pipes; plastic factories

Wisconsin advises testing if your well is near a landfill, industrial site, gas station or dry cleaner. EPA’s list of tests to add for private wells includes VOCs for wells near industrial or commercial sites.

Chlorinated city water contains another group: trihalomethanes (TTHMs), disinfection byproducts that form when chlorine reacts with organic matter. EPA regulates them separately at 80 µg/L.

Health and household effects

Health effects depend on the compound, the level and how long you are exposed. EPA’s health table lists:

• Benzene: anemia, decrease in blood platelets, increased risk of cancer.
• TCE and PCE: liver problems, increased risk of cancer.
• Vinyl chloride: increased risk of cancer.
• TTHMs: liver, kidney or central nervous system problems, increased risk of cancer.

Drinking is not the only route. Wisconsin’s health department says VOCs such as TCE and benzene can escape from water used for showering, bathing, dishwashing and laundry, and that breathing the vapors can be a significant source of exposure. That is the main reason whole-house treatment matters for VOCs when it often does not for metals.

You usually cannot rely on taste, smell or staining to tell you VOCs are present. Testing is the only reliable check.

Limits and what they mean

Compound	EPA MCL	EPA health goal
Benzene	5 µg/L	Zero
TCE	5 µg/L	Zero
PCE	5 µg/L	Zero
Vinyl chloride	2 µg/L	Zero
Total trihalomethanes	80 µg/L	Not set

EPA sets separate limits for more than 20 VOCs, so check any lab result compound by compound against the table. A health goal of zero means EPA considers no level free of risk; the MCL is the enforceable limit for public systems. Private wells are not covered by these rules.

How common are they? A USGS study of more than 2,000 domestic wells found organic compounds, including VOCs, “frequently detected at low concentrations” but “seldom” above health benchmarks: each of the few that exceeded one did so in fewer than 1% of wells.

How to test

Order a VOC screen from a state-certified lab. Wisconsin’s state lab charges $141 and lists about 21 business days for results. Ask your health department whether there is known contamination near you, which also tells you which compounds to look for.

VOCs evaporate easily, so use the lab’s own vials and follow its filling instructions exactly. Our well testing guide covers labs and what else to test.

On city water, read your Consumer Confidence Report before spending money on a test.

Treatment options

Method	How well it works	Certification to look for	Cost range
Whole-house activated carbon	High, and covers shower and laundry exposure	NSF/ANSI 53 VOC reduction	$500 to $3,000
Point-of-use carbon	High for drinking water	NSF/ANSI 53 VOC reduction	$10 to $100
Reverse osmosis	Moderate on its own; carbon stages do most of the work	NSF/ANSI 58 individual VOC claims	$300 to $1,500
Aeration (air stripping)	High for many VOCs, TCE and vinyl chloride (MDH)	None common	$800 to $4,000

Cost ranges are Minnesota Department of Health estimates based on 2017 and 2018 quotes, low end self-installed and high end professionally installed.

Wisconsin’s health department lists carbon filtration certified to NSF/ANSI 53 as the device type for VOCs. Carbon has a finite capacity, so replace it on schedule and test the treated water after installation and periodically after that. Our whole-house filter picks and well water picks compare carbon systems, and the filter finder shows which products hold VOC claims. For how whole-house and point-of-use approaches compare, see whole-house filter vs reverse osmosis.

When to call a professional

If a well test shows any VOC above its EPA limit, call your state health or environmental agency before choosing treatment. A VOC detection often means a contamination source nearby, and the agency can tell you whether it is tracking one.

Use a water treatment professional to size whole-house carbon for your flow and the specific compound, and to set a media replacement schedule. Keep testing the treated water: carbon that is exhausted can let VOCs through without any change you would notice.