VOCs (volatile organic compounds) are EPA-regulated contaminants present in the air you breathe and in your drinking water. VOCs originate from a host of common household products, from bug sprays to paint thinners. Through spillage and runoff, they can end up in your water supply.

John Woodard, our Master Water Specialist, explains what VOCs are, how to test for them, and how to remove them from your water supply. 

What are VOCs? 

Volatile organic compounds, abbreviated as VOCs, are organic chemicals with very low boiling points. Consequentially, when exposed to normal air temperatures they will readily turn into gases and vapors. Their ability to convert to gas even in temperatures well below freezing is called volatility. 

Where do VOCs come from?

VOCs are common in the atmosphere because they are present in many regularly used household products. VOCs come from paint, gasoline, solvents, inks, glues, magic markers, and dry erase pens, to name a few. The distinct odor when you take the cap off of a permanent marker is an example of a VOC in action. That smell is a volatile organic compound releasing into a vaporous form after exposure to room temperature air. VOCs can also come from spray adhesives, pesticides, upholstery, caulking agents, cleaning products, and air fresheners. 

How do VOCs get in water? 

Most VOCs enter the water supply directly as a result of human activity. Improper disposal of volatile organic compounds causes them to leach into the ground. Once they’ve infiltrated the groundwater, they can migrate from aquifers to lakes and reservoirs. Precipitation can further carry them to water supplies like wells and municipal plants. Some VOCs are created are the result of chemical reactions that take place during water disinfection processes. However, waterborne VOCs are a bit different than their airborne counterparts. They don’t have the distinct taste or smell associated with many airborne VOCs, like gasoline. If your water has a high level of volatile organic compounds, it’s most likely one of three contaminants. 

The three most common waterborne VOCs: 

  • Trihalomethane: Trihalomethane is the most common VOC found in water. Trihalomethane is a byproduct of water disinfection. When a municipal water treatment plant wants to sterilize water to distribute throughout the city, they add chlorine. When a water supply with organic content present is chlorinated, the organics and the chlorine will combine and create trihalomethane as a byproduct. This happens when city suppliers chlorinate water from lakes or rivers. Because of how widespread this disinfection method is, trihalomethane is the most common waterborne VOC. When a private well owner puts chlorine in their well, the same trihalomethane compound is created. 
  • PCE (Perchloroethylene): PCE is a byproduct of solvents. PCE is commonly used in dry cleaning and as a degreaser at industrial sites. It is also found in consumer products like shoe polish and solvents used for diluting and breaking down inks. 
  • MTBE (Methyl tert-butyl ether): MTBE is a fuel additive. After lead was no longer legally allowed to be used with gasoline, MTBE was substituted to raise the octane number of the gas. After its usage became extensive, MTBE began to appear in water. From spillages to underground storage tank leakage, MTBE has caused swathes of groundwater and soil to become contaminated. 

What is my risk of VOC exposure? 

High VOCs are more apt to be found in groundwater well supplies than they are in city water. However, city water also will have VOC levels, though you will not see them in high abundance. The EPA regulates 23 volatile organic compounds, meaning city water suppliers are required to monitor these. If they should ever rise above a maximum contaminant level set by the EPA, then the city supplier has to take action to reduce the levels so that they are below the maximum contaminant level. Nonetheless, it is important to regularly test your groundwater to make sure your VOC levels are not too high, especially if you are a private well owner. 

Are VOCs dangerous? 

It is difficult to generalize the dangers of waterborne VOCs because there so many different variations of them. Furthermore, there has not been extensive testing done to determine the health risks posed by many of the household products that release VOCs. But, there is evidence exposure to VOCs has negative side effects. According to the EPA, Volatile organic compounds are associated with irritation of the eyes, nose, and throat, headaches, loss of coordination, and nausea. Prolonged exposure can cause damage to the liver, kidneys, and central nervous system. Whether or not they are carcinogenic is still contested. Some organics have manifested as cancerous in animals, and there are some that are suspected to cause cancer in human beings. 

How do you test for VOCs in water? 

The only way to effectively test VOCs in water is to take a water sample and send it to a certified laboratory. The National Testing Laboratories' Watercheck test kit makes this process incredibly easy. In addition to bacteria and heavy metals, it tests for trihalomethanes and 44 other VOCs that could be in your water. If you depend on a well for your home water supply, you should test your water for volatile organic compounds every year. The only way to reliably know if your VOC levels are too high is to test your water periodically. Waterborne VOCs don’t necessarily have a smell, a taste, or a color. So, you could unknowingly have high levels of VOCs if you do not run tests on your water.  

How do you remove VOCs from water? 

Carbon filters are very effective at removing VOCs from water. Since VOCs are organic compounds, they are carbon-based. The adsorption properties of the activated carbon filter allow it to grab hold of the carbon-based VOC. There is no better defense mechanism against VOCs in your water than carbon. Carbon filters come in many various shapes, sizes, and applications. If you have a refrigerator filter that's carbon guaranteed, that will remove the VOCs from your refrigerator water. You can install carbon filters under the sink, on your counter-top, or even as a whole house filtration system. This has the added benefit of removing chlorine and chloramines, which will greatly improve the taste of your drinking water throughout your house. 

If you are using a point-of-use drinking water filter, you do want to make sure it is rated for VOC reduction. VOCs will exhaust filtration media much faster than chlorine will. For effective volatile organic compound reduction, it is important not to overrun the filter's capacity. 

Learn more about the extraordinary filtration properties of carbon: Activated Carbon Filters 101

Does RO remove VOCs?

Reverse osmosis systems will take out VOCs, but only if they have a carbon pre-filter or post-filter. By itself, the reverse osmosis process cannot take out VOCs. The VOCs will pass through the membrane just like oxygen does. Fortunately, carbon filters are very commonly installed with VOCs. And if they do manage to pass through the membrane, your carbon post-filter will remove it before it touches your drinking water.


VOC Rated Under-Sink Filter
VOC-Rated Carbon Filter


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