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Last updated: February 27, 2026

How to Remove VOCs from Drinking Water

This page covers health-related contaminants in drinking water. It is not medical advice. If you have concerns about VOC exposure, talk to your doctor. In emergencies, call 911.

Activated carbon is the right tool for most VOCs. The challenge is knowing which specific VOCs you have, which filter is certified to remove them, and whether point-of-use or whole-house treatment makes more sense for your situation.

Start with a test. VOCs in water have no taste or smell at most concentrations, so you won’t know you have them without a lab panel. Test your water before choosing treatment, because source water varies by region and well.

How Carbon Adsorption Works for VOCs

Activated carbon removes VOCs through a process called adsorption. VOC molecules are drawn to the carbon surface and stick to it as water flows through. Activated carbon has an enormous surface area because of its porous structure. A single gram can have a surface area of 500 to 1,500 square meters.

The key variable is contact time. The longer water spends in contact with the carbon, the more completely VOCs are adsorbed. Fast flow rates reduce contact time and reduce removal efficiency.

Granular activated carbon (GAC) consists of loose carbon granules packed in a tank or cartridge. Water flows around the granules. GAC is used in most whole-house systems and many faucet-mounted filters.

Carbon block compresses activated carbon into a solid block. Water must flow through the block rather than around loose granules. This creates longer contact time at the same flow rate and is generally more effective for VOC removal. Most under-sink and pitcher filters use carbon block.

For point-of-use drinking water filtration, a carbon block filter outperforms a comparably sized GAC filter for VOC removal. For whole-house applications where a large GAC tank is properly sized for your flow rate, the contact time advantage of carbon block matters less.

Why NSF Certification Is Model-Specific

NSF/ANSI 53 is the standard that covers health effects contaminants, including specific VOCs like benzene, toluene, and trichloroethylene (TCE). But “NSF 53 certified” on a filter box doesn’t mean the filter was tested for all VOCs.

The NSF certification is specific to each model and each contaminant. To know what a filter is actually certified to remove, look up the specific model number in the NSF product database at nsf.org/certified-products. The database shows the complete list of contaminants and reduction percentages for that exact product.

A filter might be NSF 53 certified for lead and cysts but not for any VOCs. Another might be certified for benzene but not toluene. The only way to know is to check the certification details for the specific model.

This matters if you have a specific VOC from your water test. If your test found trichloroethylene, you need a filter with NSF 53 certification that specifically lists TCE reduction, not just a filter that says “NSF 53” on the box.

Point-of-Use vs. Whole-House

Where you filter depends on which exposure pathways you’re trying to address.

Drinking and cooking: A point-of-use carbon block filter under the kitchen sink or an RO system with carbon filtration handles this. This is the minimum for VOC treatment and protects the highest-priority exposure route.

Shower inhalation: Several VOCs, including benzene, chloroform, and some chlorinated solvents, are volatile enough to off-gas from hot shower water into the steam you breathe. Studies measuring VOC inhalation during showering show that shower exposure can equal or exceed drinking water exposure for volatile compounds. A point-of-use kitchen filter does nothing for this. Only whole-house treatment addresses shower inhalation.

Laundry and skin contact: Whole-house filtration addresses these. For most VOCs at typical groundwater concentrations, skin absorption through washing is a lower exposure pathway than drinking or inhalation. But if you have elevated benzene levels, a whole-house approach is worth considering.

If you find benzene in your well at any detectable level, the case for whole-house treatment is strong. The EPA’s MCLG for benzene is zero, meaning no safe level has been established.

See best whole-house water filters for whole-house carbon options, and best under-sink water filters for point-of-use carbon and RO systems.

Step-by-Step: Choosing a System

Step 1: Test for specific VOCs. A general VOC panel from a certified lab identifies which compounds are present and at what concentrations. This tells you what you’re actually dealing with.

Step 2: Match your VOCs to NSF certifications. Take your test results and look for filters certified under NSF/ANSI 53 for those specific compounds. Use the NSF product database to check model-by-model, not just brand claims.

Step 3: Decide on point-of-use or whole-house. If your VOCs are at low concentrations and your exposure concern is primarily drinking water, point-of-use carbon block handles it. If you have elevated levels of volatile compounds, or if shower inhalation is a real concern, whole-house GAC is the right answer.

Step 4: Size whole-house systems properly. For a whole-house GAC system, the tank needs to be sized based on your household flow rate and your VOC concentrations. Under-sizing is the most common mistake. Contact time must be maintained even at peak flow.

Step 5: Verify after installation. Test your filtered water 2-3 weeks after the system is running. Confirm the VOC levels are reduced to acceptable concentrations. Don’t assume the filter is working.

Maintenance and Monitoring

Carbon exhausts over time. The pores fill with adsorbed contaminants and the filter loses effectiveness. When carbon is exhausted, contaminants pass through.

Point-of-use carbon block filters need replacement every 3-6 months for typical household use. If your VOC levels are elevated, replace on the shorter end of that range. Follow manufacturer guidance but err on the side of more frequent replacement.

Whole-house GAC media typically needs replacement every 1-3 years. Higher VOC concentrations exhaust the media faster. Some systems have indicators, but the most reliable check is annual testing of your treated water for the specific VOCs you’re treating.

Signs that carbon may be exhausted: taste or odor returns to filtered water (for VOCs with detectable taste or odor), or an annual test shows VOC levels approaching your pre-filter concentrations.

Test your raw well water for the full VOC panel every few years, not just TDS or basic chemistry. VOC contamination from nearby industrial sites, underground storage tanks, or historic land use can appear or increase over time. Knowing your baseline and checking it periodically is the responsible approach for well owners.

For lab testing options, see best mail-in water tests.

Related pages: VOCs in Drinking Water | Best Whole-House Water Filters | Best Under-Sink Water Filters | Best Mail-In Water Tests

Sources

This page covers health-related contaminants in drinking water. It is not medical advice. If you have concerns about VOC exposure, talk to your doctor. In emergencies, call 911.

Frequently Asked Questions

Does reverse osmosis remove VOCs?
Partially. RO membranes are most effective at removing ionic contaminants (metals, nitrates, fluoride). Smaller, uncharged VOC molecules can pass through RO membranes to some extent, though most RO systems include a carbon pre-filter or post-filter that adsorbs VOCs. An RO system with carbon filtration provides better VOC coverage than the RO membrane alone.
What NSF certification covers VOC removal?
NSF/ANSI 53 covers health effects contaminants including specific VOCs. When you look up a filter in the NSF product database, you'll see a list of contaminants the filter is certified to reduce. That list is specific to the model. "NSF 53 certified" on a box doesn't mean the filter has been tested for every VOC. Check which VOCs appear on the certification list for the specific model you're considering.
Will a whole-house carbon filter remove all VOCs?
A properly sized whole-house granular activated carbon (GAC) filter reduces most VOCs if they're present at typical groundwater concentrations. Sizing matters, because contact time between water and carbon determines effectiveness. Too fast a flow rate or an undersized unit reduces effectiveness. A water treatment professional can size the system based on your VOC test results and your household flow rate.
How long does a carbon filter last for VOC removal?
The carbon media in a whole-house GAC filter typically needs replacement every 1-3 years, depending on your water quality and VOC levels. Higher VOC concentrations exhaust the carbon faster. Point-of-use carbon block filters (under-sink or pitcher) need more frequent replacement, typically every 3-6 months. An annual test of your filtered water is the reliable way to confirm the filter is still working.
Do I need to filter for VOCs in my shower?
Some VOCs are volatile enough to off-gas from shower water into the air you breathe. For people with confirmed high levels of specific VOCs (particularly benzene, toluene, or chloroform), inhalation during showering is a real exposure pathway. A whole-house carbon filter addresses this better than a point-of-use kitchen filter. If you only have an under-sink filter, your shower exposure isn't reduced.