When it comes to removing harmful chemicals from your drinking water, reverse osmosis is one of the best methods available. But does reverse osmosis remove VOCs?
Reverse osmosis can remove many VOCs from drinking water. However, some VOCs are more effectively treated than others, and you need to look at the specific compounds to know whether RO is effective or not. Chemicals that are very soluble in water, such as vinyl chloride, are not removed very well by RO. Large organic molecules, such as dichloromethane, are removed very effectively. Solvents like benzene and toluene, can be treated at low to moderate concentrations, but grossly contaminated water may saturate the membrane in a relatively short period of time.
In this guide, we will explore howe well reverse osmosis treats VOCs and much more. We’ll discuss what VOCs are, how they can affect your health, and how reverse osmosis works to remove them from your water supply. By the end of this article, you’ll have a better understanding of whether or not reverse osmosis is right for you and your home.
What Are VOCs
Volatile organic compounds, also known as VOCs, are a type of chemical that can be found in many common household products. Some examples of items that may contain VOCs are paint, cleaners, and air fresheners. These chemicals can also be released into the air from burning fossil fuels such as oil or gasoline.
The USGS estimates that more than one in five private wells tested nationwide contains at least one volatile organic compound above the EPA’s maximum contaminant level.
VOCs can be harmful to your health in a number of ways. They have been linked to cancer, liver damage, kidney damage, and central nervous system damage. Inhaling or coming into contact with VOCs can also cause irritation to the eyes, nose, and throat. Short-term exposure to high levels of VOCs can cause headaches, dizziness, and nausea.
Because of the dangers they pose to our health, it’s important to remove them from our homes whenever possible.
How do VOCs get in my drinking water?
VOCs are easily dissolved and leach into groundwater, so private wells near industrial or commercial areas, gas stations, landfills, railroad tracks or farm fields can be at risk of contamination. These chemicals can enter drinking water systems through leaks, accidental spills and improper disposal.
Most common VOCs
There are literally thousands of VOCs, but some are more common and pose a greater risk to human health than others. The most common VOCs found in drinking water include:
- Benzene
- Toluene
- Xylene
- Methyl tertiary butyl ether (MTBE)
- Trichloroethylene (TCE)
- Perchloroethylene (PCE)
- Trihalomethanes (THMs)
These VOCs are all man-made chemicals with a variety of uses. Benzene, for example, is used as a solvent and in the production of plastics, while TCE is used as a degreaser and an industrial cleaning agent. Xylenes are found in gasoline and MTBE was once added to gasoline to improve its combustion.
PCE and TCE are the most common VOCs found in drinking water, according to a 2009 report from the U.S. Geological Survey (USGS).
VOCs and Your Health
While VOCs in drinking water at low levels aren’t likely to cause health problems, some people who drink water containing VOCs in excess of EPA’s maximum contaminant level (MCL) for many years could experience problems with their liver, kidney and central nervous systems, and may have an increased risk of cancer.
It’s important to note that the MCL is not a health goal, but rather a maximum level of a contaminant that is allowed in drinking water. This means that there is still some risk to your health even if your water contains VOCs below the MCL.
If you are concerned about VOCs in your drinking water, you should have it tested by a certified laboratory. You can also contact your local or state health department for more information.
Reverse Osmosis
Reverse osmosis (RO) is a water treatment technology that can be used to remove a variety of contaminants from drinking water, including many VOCs. RO removes contaminants from water by using pressure to force water molecules through a semipermeable membrane. As water is forced through the RO membrane, contaminants are left behind and filtered water is collected on the other side.
Reverse osmosis works by using high pressure force water through a semipermeable membrane. The RO membrane is made of very thin layers of synthetic material that have tiny pores. The pores in the RO membrane are small enough to allow water molecules through, but too small for most contaminants.
This means that as water is forced through the membrane under pressure, contaminants are left behind in a concentrated waste solution known as brine. The brine is discharged to the drain or stored and disposed of offsite. Filtered water is collected on the other side of the membrane.
Does RO remove VOCs
Reverse osmosis can remove a wide variety of contaminants from water, including dissolved minerals, bacteria, viruses, and many VOCs. Several studies have demonstrated that RO has potential to remove VOCs from drinking water. Since VOCs are a large group of many different chemicals, the effectiveness of RO to remove them varies by compound.
Some VOCs are very effectively removed by reverse osmosis, some are partially treated by RO, while others aren’t removed at all.
The following table summarizes the effectiveness of RO to remove VOCs from drinking water. It also includes the USEPA MCL which is a helpful standard to understand how toxic a particular VOC might be.
| VOC | EPA MCL (mg/L) | RO Removal Efficiency |
| Benzene | 0.005 | Moderate |
| Toluene | 1 | Moderate |
| Xylene | 10 | Moderate |
| Methyl tertiary butyl ether | NA | Very Effective |
| Trichloroethylene | 0.005 | Moderate |
| Perchloroethylene | 0.005 | Moderate |
| Trihalomethanes | 0.080 | Very Effective |
The type of membrane has a significant effect on how well the RO filter removes VOCs. Membranes made of cellulose, polyamide, and think film composite membranes performed less effectively than those made of special polymers.
Many RO filters include activated carbon filters. Activated carbon is a benchmark technology for removing VOCs – this means that it is the gold standard that all other technologies are compared to. If your RO filter includes a carbon filter, its ability to remove VOCs will be significantly improved.
National Sanitation Foundation (NSF/ANSI) Standard 58
Look for a reverse osmosis system with a National Sanitation Foundation (NSF/ANSI) Standard 58 certification. NSF/ANSI 58 is the American National Standard for point-of-use (POU) reverse osmosis (RO) systems.
The NSF standard addresses a wide range of quality and performance standards for RO systems, including:
- Wetted materials and their safety
- Construction quality
- Reduction of TDS (total dissolved solids)
- Efficiency and recovery
- Contaminant reduction (verified through testing)
Testing Your Water for VOCs
If you want to know for sure whether VOCs are present in your water, the only way to find out is to have your water tested. A qualified water testing laboratory can analyze your water and tell you what contaminants are present and at what levels.
If you are concerned about VOCs in your water, the best thing to do is to have your water tested.
Laboratory testing
The most reliable and accurate way to test for VOCs is to send a water sample to a qualified water testing laboratory. A trained technician will analyze your water and provide you with a report that lists the contaminants present and their levels.
Check out Tap Score and their laboratory services for homeowners.
Home test kits
If you want to test your water yourself, you can purchase an at-home water testing kit. These kits are less accurate than laboratory testing but can give you a general idea of what contaminants are present in your water.
Other Methods to Remove VOCs from Water
If you are looking to remove VOCs from your water, it is important to understand the types of filters that are available and how effective they are at removing these chemicals. There are a few different methods that can be used to remove VOCs from water.
Activated carbon filters
Activated carbon is a benchmark treatment for VOCs, which means it sets the gold standard for all other methods. Activated carbon, also known as charcoal, is made from materials like coal, wood, and coconut shells. The pores in the activated carbon attract and trap VOCs, effectively removing them from the water.
The base material is heated to very high temperatures to create charcoal. This material is then exposed to high temperatures and steam to create tiny pores in the charcoal. The pores in the activated carbon attract and trap VOCs, effectively removing them from the water.
Air stripping
Air stripping is another common method of removing VOCs from water. In this process, air is bubbled up through the water in order to strip the VOCs from it. As the small air bubbles contact the VOCs in water, these molecules volatize into the air and are removed from the water. This process is very effective for molecules that have a high vapor pressure and low solubility.
Oxidation
Oxidation is another method of removing VOCs from water. In this process, the water is exposed to an oxidizing agent which breaks down the VOCs into harmless compounds – carbon dioxide and water.
FAQs
Does boiling water remove VOCs?
Boiling tap water is often used to remove certain VOCs from contaminated water, but it isn’t a reliable method to purify drinking water. Boiling water may also release more volatile organic compounds into the air in your home resulting in a health risk. This process can also concentrate heavy metals which make the water more toxic.
Does my water softener remove VOCs?
Water softeners do not remove VOCs from water. They use an ion exchange resin to remove calcium and magnesium, but most VOCs do not adsorb to this media.
Do refrigerator filters remove VOCs?
If your refrigerator filter has activated carbon, then it will remove most VOCs that might be in your drinking water. However, these filters only have a small amount of carbon, and they don’t have a long enough column to use them as a primary method of removing toxic VOCs from your drinking water.
Conclusion
While reverse osmosis is an effective method for removing VOCs from water, it is important to understand that not all systems are created equal. It is also important to have a pre-filter and post-filter in place in order to remove any residual VOCs that may have passed through the membrane. If you are looking for a reliable way to remove VOCs from your water, activated carbon filters are the gold standard.