How to Test for Emerging Contaminants in Private Well Water

Private well owners increasingly face a new class of water quality threats—emerging contaminants. Unlike traditional pollutants like bacteria, nitrates, or lead, these substances include pharmaceuticals, personal care products, industrial chemicals, and per- and polyfluoroalkyl substances (PFAS). Many are not yet regulated under the Safe Drinking Water Act, yet scientific evidence suggests they may pose risks to human health even at trace levels. For families relying on private wells, which are not subject to federal testing requirements, proactive monitoring is the only line of defense. This article provides a comprehensive guide to understanding, testing for, and addressing emerging contaminants in private well water.

Understanding Emerging Contaminants

Emerging contaminants, also called contaminants of emerging concern (CECs), are chemicals and microorganisms that have been detected in water supplies but are not commonly monitored or regulated. Their presence is often linked to modern human activities: pharmaceuticals from household waste, microplastics from synthetic fabrics, flame retardants from furniture, and pesticides from agriculture. Because treatment technologies were not designed to remove them, they can persist through conventional water filtration and enter groundwater and private wells.

The U.S. Environmental Protection Agency (EPA) periodically updates its Contaminant Candidate List (CCL) to identify unregulated contaminants that need further study. The current CCL 5 includes over 90 substances, such as PFAS, 1,4-dioxane, hormones, and cyanotoxins. Many of these are now routinely detected in private well samples from areas near landfills, farms, or industrial sites.

Sources vary widely. Septic systems can release pharmaceutical residues and personal care products. Agricultural runoff carries antibiotics, hormones, and pesticides. Industrial discharges contribute solvents, plasticizers, and firefighting foam chemicals. Even rainwater can deposit atmospheric pollutants like polycyclic aromatic hydrocarbons (PAHs). Understanding the potential sources in your region helps narrow down which contaminants to test for.

Health Implications

Scientific research continues to uncover health effects associated with chronic, low-level exposure to emerging contaminants. For example, PFAS have been linked to immune system suppression, thyroid disruption, and certain cancers. Pharmaceutical residues may contribute to antibiotic resistance or endocrine disruption. Microplastics can carry adsorbed toxins into the body. While regulatory limits for many CECs do not yet exist, health advisory levels have been established for some, such as the EPA’s lifetime health advisory of 70 parts per trillion for two common PFAS compounds.

Why Private Well Owners Should Be Concerned

Unlike public water systems, which are required to test for regulated contaminants and report results, private well owners are solely responsible for their water quality. The EPA estimates that over 13 million U.S. households rely on private wells, and a significant percentage have never been tested for contaminants beyond basic bacteria and nitrates. Emerging contaminants often escape these standard tests.

Geographic location matters. Wells in agricultural regions may face higher risks from pesticides and veterinary pharmaceuticals. Wells near airports, military bases, or fire-training facilities are more likely to contain PFAS from aqueous film-forming foam (AFFF). Suburban areas with aging septic systems may see elevated levels of pharmaceuticals and personal care products. Even wells in seemingly pristine rural areas can be affected by atmospheric deposition of industrial pollutants.

Regulatory gaps compound the problem. The Safe Drinking Water Act does not apply to private wells, so homeowners cannot rely on government monitoring. Testing for emerging contaminants is strictly voluntary, and many laboratories do not offer these advanced analyses without a specific request. As a result, contamination can go undetected for years, leading to long-term exposure.

Key fact: A 2020 study by the U.S. Geological Survey found at least one emerging contaminant in more than 60% of sampled private wells across the country.

Proactive testing is the only way to know your water’s safety. Waiting for regulatory action or visible signs of contamination—emerging contaminants are often odorless, tasteless, and colorless—is not a viable strategy.

The Challenge of Testing for Emerging Contaminants

Testing for CECs is fundamentally different from routine well water analysis. Standard kits screen for coliform bacteria, nitrates, pH, hardness, and a handful of heavy metals. Emerging contaminants require specialized instrumentation such as liquid chromatography–mass spectrometry (LC-MS/MS) or gas chromatography–mass spectrometry (GC-MS). These methods can detect compounds at parts-per-trillion concentrations, but they are expensive—typically $200 to $800 per test—and require expert interpretation.

Selecting a Certified Laboratory

Not all laboratories can perform these analyses. When choosing a lab, verify that it is accredited by a recognized body, such as the National Environmental Laboratory Accreditation Program (NELAP) or the state health department. Ask specifically whether the lab can test for the contaminants you are concerned about—some specialize in PFAS, others in pharmaceuticals, and few test for both.

The EPA maintains a list of laboratories approved for drinking water analysis under the Safe Drinking Water Act. However, many of these labs focus on regulated contaminants. For emerging contaminants, you may need to contact university research labs or commercial environmental firms that offer advanced services. Be prepared to provide information about your well construction, nearby activities, and any known contamination incidents to help the lab recommend an appropriate test panel.

Sample Collection and Handling

Proper sampling is critical. Emerging contaminants can degrade, adsorb to container walls, or become contaminated during collection. Most labs supply specific containers—often amber glass bottles for organic compounds, or plastic bottles with preservatives for metals and perfluorinated chemicals. Follow these guidelines:

Flush the well for 15–30 minutes before sampling to clear stagnant water from the plumbing.
Avoid sampling from hoses, aerators, or water softeners. Use a cold-water faucet directly from the well's pressure tank.
Wear disposable gloves to prevent introducing contaminants from your hands.
Fill containers exactly as instructed—some require a headspace, others must be filled to the brim.
Ship or deliver samples overnight on ice, as many CECs are unstable over time.

Chain-of-custody forms are often required to document sample handling. Fill them out completely and include a request for the specific analytes. If the lab detects a contaminant, they will need this information to provide concentration data and comparison with any available health advisories.

Step-by-Step Guide to Testing Your Well Water

1. Identify Contaminants of Concern

Begin by researching what may be in your area. Local health departments often have data on known contamination issues, such as PFAS from nearby military bases or nitrates from agricultural use. The EPA’s “How’s My Waterway” tool can show surface water quality trends that sometimes correlate with groundwater. Also, review well construction records: shallow wells are more vulnerable to surface contamination, while deeper bedrock wells may have different challenges.

Consider your household’s specific risks. If anyone in the home is immunocompromised, pregnant, or young, the threshold for concern may be lower. Some emerging contaminants, like endocrine-disrupting compounds, may pose greater risks during developmental windows.

2. Select a Laboratory and Test Panel

Once you know which contaminants to target, contact several accredited labs and ask for quotes. Many labs offer “emerging contaminant panels” that bundle the most common CECs—for example, a PFAS panel (typically 18–30 compounds), a pharmaceutical and personal care product panel (20–50 compounds), and a volatile organic chemical (VOC) panel (60+ compounds). Costs add up quickly, so prioritize based on your risk assessment.

For first-time testing, a broad initial screen can be worthwhile, but be prepared for higher costs. Alternatively, start with the most likely contaminants: PFAS near known sources, pharmaceuticals near septic fields, or pesticides near farmland. Some state health departments offer subsidized testing programs for certain contaminants, especially PFAS. Check with your local environmental agency.

3. Collect and Submit Samples

Review the lab’s sampling instructions well in advance. Schedule collection early in the week so you can ship overnight before a weekend. Use only the containers provided—do not rinse them, as some may contain preservatives. Label each container with the sample ID, date, time, and your initials. Fill out the chain-of-custody form and include payment. Some labs offer “sample pickup” via courier; others require you to drop off or ship.

4. Review Results and Take Action

Lab reports for emerging contaminants typically list each analyte, its concentration in parts per trillion (ppt) or parts per billion (ppb), the method detection limit (MDL), and any available health advisory or regulatory limit. Compare your results to EPA lifetime health advisories or state-specific guidance. If no advisory exists, you may need to consult a toxicologist or water treatment professional to evaluate risk.

If contaminants are detected above recommended levels, you have several options:

Point-of-use treatment: Activated carbon filters can reduce many organic contaminants, including PFAS, pharmaceuticals, and pesticides. Reverse osmosis systems are effective for a broad range of CECs, including most ions and organic molecules.
Whole-house treatment: Granular activated carbon or anion exchange systems can treat all water entering the home. These are more expensive but protect you during bathing and washing, as some contaminants can be absorbed through skin.
Alternative water source: If contamination is severe or treatment costs are prohibitive, you might consider drilling a deeper well (if the aquifer is different) or installing a rainwater collection system for drinking water.

Always verify that the treatment system is certified to remove the specific contaminants found. The NSF International and Water Quality Association (WQA) maintain databases of certified products.

5. Ongoing Monitoring

Emerging contaminant levels can fluctuate with seasons, rainfall, and changes in land use. Retesting every one to two years is recommended, especially if you live near a potential source. Keep detailed records of all test results, including the lab name, date, and method. This history can help spot trends and justify the need for treatment upgrades.

Interpreting Test Results and Taking Action

Understanding lab data can be daunting. Focus on the detection frequency and magnitude relative to health guidance. For PFAS, the EPA has established a health advisory of 70 ppt for combined PFOA and PFOS. Some states have set lower limits (e.g., 20 ppt for the sum of certain PFAS). If your results exceed these, immediate action is warranted.

For pharmaceuticals, few health advisories exist. In such cases, compare your levels to those seen in published studies or drinking water screening levels from the EPA’s Integrated Risk Information System (IRIS). It may be helpful to work with a water quality consultant or your local extension service.

If your results are below detection limits, that does not guarantee safety—there may be other unmeasured compounds, or the detection limit may be too high to capture very low levels. Nevertheless, non-detect results for the most likely contaminants provide reasonable reassurance.

Treatment Options at a Glance

Contaminant Type	Effective Treatment	Considerations
PFAS	Granular activated carbon, anion exchange, reverse osmosis	Carbon media must be replaced regularly; select NSF-certified filters
Pharmaceuticals	Reverse osmosis, advanced oxidation, activated carbon	RO removes most; carbon works well for many but not all
Pesticides	Activated carbon (specific types), reverse osmosis	Check compatibility; some pesticides require specialized media
1,4-Dioxane	Advanced oxidation (UV/H2O2), reverse osmosis	Carbon is ineffective; requires specialized treatment

Preventing Contamination

Testing is essential, but prevention is even better. Maintaining your well and septic system reduces the risk of emerging contaminants entering the groundwater.

Well Maintenance

Inspect the wellhead yearly for cracks, loose seals, or damage. Keep the area free of debris, fertilizers, and animal waste.
Ensure the well casing extends at least one foot above ground and the cap is tightly sealed.
Test your well annually for coliform bacteria and nitrates as a baseline; changes in these indicators may signal broader contamination.

Septic System Care

Pump the septic tank every three to five years to prevent overflows and groundwater contamination.
Never dispose of pharmaceuticals, household chemicals, or personal care products down the drain. Use a medication take-back program instead.
Install a septic system that meets current codes and is properly sited away from the well.

Land Use Considerations

If you have a private well, avoid applying pesticides or fertilizers within 100 feet of the wellhead.
Store gasoline, paint, solvents, and other chemicals in a secure, impermeable container away from the well.
Monitor any industrial or agricultural neighbors and communicate concerns to local environmental agencies.

Resources and Support

Navigating the world of emerging contaminants can be overwhelming. Fortunately, several reliable organizations provide information and assistance.

EPA Contaminant Candidate List: The CCL 5 details unregulated contaminants under consideration for regulation. It can guide your testing priorities.
CDC Private Well Testing: The CDC’s well testing page offers general guidance and links to state resources.
Water Quality Association (WQA): The WQA’s contaminants of emerging concern page provides fact sheets and treatment recommendations.
State Drinking Water Programs: Contact your state health department or environmental agency. Many have emerging contaminant monitoring programs and may offer assistance with testing or funding.
Local University Extension Services: Cooperative Extension offices often have water quality specialists who can interpret test results and recommend actions.

Remember, when in doubt, consult a certified water treatment professional who has experience with emerging contaminants. They can design a treatment system tailored to your specific water chemistry and contaminant profile.

Testing for emerging contaminants in private well water is an investment in your family’s health. While the process may seem complex—with specialized labs, high costs, and nuanced interpretation—the peace of mind and protection it provides are invaluable. By staying informed, choosing appropriate tests, and taking proactive steps to treat or prevent contamination, you can ensure that your well remains a safe, reliable source of drinking water for years to come.