How to Test Your Water for Carcinogens: A Homeowner Guide
Some drinking water contaminants, including arsenic, benzene, and certain PFAS,
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Some drinking water contaminants, including arsenic, benzene, and certain PFAS, have been linked to cancer. They can enter water through natural deposits, industrial pollution, and other sources, often without changing its appearance, taste, or smell.
Testing can help identify these chemicals, but there's no single water test that detects every potential carcinogen. The right choice depends on your water source and the contaminants you're concerned about.
This guide explains which cancer-related contaminants to consider, how to choose the right laboratory tests, and what your results can tell you.
A carcinogen is a substance that can cause cancer. Some chemicals found in drinking water have been classified as carcinogenic based on studies involving humans, animals, or other scientific evidence.
The International Agency for Research on Cancer (IARC) uses several classifications:
These categories describe how strong the evidence is that a substance can cause cancer. They do not indicate how dangerous a particular concentration is or predict an individual's likelihood of developing cancer.
For drinking water, the actual risk depends on several factors, including the contaminant, its concentration, how long someone is exposed, and how exposure occurs.
You can read more about this distinction in IARC's explanation of carcinogen classifications.
The contaminants most relevant to your water depend partly on where it comes from. Private wells and public water supplies face different contamination risks, so they may require different testing approaches.
Private wells can be affected by naturally occurring contaminants in soil and rock, along with pollution from nearby activities.
For example, arsenic may enter groundwater naturally, while volatile organic compounds (VOCs) and PFAS may be concerns near industrial sites, landfills, or other contamination sources. Radon may also occur in groundwater in certain geological areas.
Unlike public water systems, private wells are not regulated under the federal Safe Drinking Water Act. Owners are generally responsible for arranging testing and maintaining their water quality, although state and local requirements may apply.
The EPA's private well guidance provides information about testing and protecting your water supply.
Public water systems must monitor contaminants regulated under federal drinking water standards. They also provide an annual Consumer Confidence Report (CCR) with information about water quality.
Start by reviewing your utility's latest report to see which contaminants were tested and what the results showed.
You can find more information through the EPA's Consumer Confidence Report resources.
However, your home's plumbing can also affect water quality. For example, lead may enter drinking water through older pipes or fixtures, even when the utility's water meets applicable standards at other monitoring locations.
If you're concerned about a specific contaminant that isn't covered by your utility's report, additional testing may be useful.
This practical testing list covers the main carcinogens in drinking water, but it doesn't include every substance ever classified as carcinogenic.
Arsenic occurs naturally in certain rocks and soils and can dissolve into groundwater. This makes it an important contaminant to consider when testing private wells, particularly in areas with known arsenic deposits.
The International Agency for Research on Cancer (IARC) classifies inorganic arsenic compounds as carcinogenic to humans (Group 1). The EPA's drinking water limit for total arsenic in public water systems is 10 parts per billion (ppb).
For more information about sources and health concerns, read our guide to arsenic in drinking water.
Testing options: ETR Laboratories offers an Arsenic Water Test ($45) and a Heavy Metals Water Test ($190) that includes arsenic and other listed metals. Our guide to testing for heavy metals explains when a broader panel may be useful.
Volatile organic compounds (VOCs) are chemicals that evaporate readily. Some can reach drinking water through fuel leaks, industrial discharges, landfills, and contaminated groundwater.
Benzene and vinyl chloride are two VOCs classified by IARC as carcinogenic to humans (Group 1).
The EPA sets the following limits for public drinking water systems:
Not all VOCs are carcinogenic, and the chemicals included in a testing panel vary by laboratory.
ETR Laboratories' VOC Drinking Water Test ($150) screens for a published list of volatile organic compounds. Our guide to how VOCs are tested in water explains the testing process and what to look for in your results.
Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic chemicals used in products such as stain-resistant materials, firefighting foams, and industrial applications.
Many PFAS break down very slowly, allowing them to persist in the environment and contaminate water sources.
The EPA's 2024 drinking water rule established limits of 4 parts per trillion (ppt) each for PFOA and PFOS in public water systems.
In May 2026, the EPA proposed extending compliance deadlines for these two substances and separately proposed removing federal limits for several other PFAS. These proposals had not been finalized as of October 2026, so the existing regulations remain in place while the agency considers changes. Check the EPA's PFAS drinking water page for the latest regulatory status.
ETR Laboratories offers a PFAS Forever Chemicals Water Test ($415) that screens for 18 listed PFAS, including PFOA and PFOS.
For more information, see our guide to detecting and treating PFAS in drinking water.
Disinfection helps make drinking water safe by killing harmful microorganisms. However, when disinfectants such as chlorine react with naturally occurring organic matter, they can form chemicals known as disinfection byproducts.
Some of these compounds, including certain trihalomethanes (THMs), have been associated with increased cancer risks after long-term exposure.
Disinfection byproducts are mainly a concern in treated public water supplies, although they can also form in other chlorinated water systems.
Our article on cancer-related byproducts of water disinfection explains the most common compounds and potential risks.
ETR Laboratories does not currently list a standalone THM test in its online catalog. If you need testing for disinfection byproducts, contact our team to confirm available options.
Some radioactive substances occur naturally in rocks and soil and can enter groundwater.
Radon is a radioactive gas that can dissolve in well water. When you shower, wash dishes, or use water around the house, some of that gas can escape into indoor air.
IARC classifies radon-222 and its decay products as carcinogenic to humans (Group 1). Breathing radon is an established cause of lung cancer.
Other radioactive elements, including radium and uranium, may also occur in groundwater. Their health effects and testing requirements differ, so a radon test cannot identify them.
ETR Laboratories offers a Radon in Water Test ($40). Standalone radium and gross alpha testing are not currently listed in our online catalog.
For more information, see our guides to uranium in well water and radium and gross alpha testing.
1,4-Dioxane is a synthetic chemical associated with certain industrial solvents and manufacturing processes. It can reach drinking water through contaminated groundwater and is difficult to remove using some conventional water treatment methods.
IARC classifies 1,4-dioxane as possibly carcinogenic to humans (Group 2B).
This chemical is not included in every VOC testing panel. ETR Laboratories does not currently list 1,4-dioxane among the analytes in its online VOC test or offer a standalone test in its published catalog.
If you're concerned about 1,4-dioxane, contact our team before ordering to confirm which testing options are available.
Our guide to 1,4-dioxane in drinking water explains the contamination sources, testing methods, and treatment challenges.
Lead is a serious health concern, but the main reason to test is harm to learning and development. EPA and CDC agree there is no known safe level of lead in a child's blood, and EPA lists an MCLG of zero for lead. IARC lists inorganic lead compounds in Group 2A (probably carcinogenic), a lower tier than arsenic and benzene.
Lead often appears on the same lists as carcinogens, but EPA highlights learning, behavior, heart and kidney effects, as the effects of lead exposure in drinking water post explains.
Lead usually comes from plumbing, since EPA names lead pipes, faucets and fixtures as the most common sources. The ETR Lead Water Test ($45) covers it. The table below pairs each contaminant with its test.
ETR Laboratories offers individual tests and broader panels for several cancer-related drinking water contaminants. The table below shows which tests cover the chemicals discussed in this guide.
| Contaminant | Potential source | ETR test | Price |
| Arsenic | Naturally occurring deposits in rock and soil | Arsenic Water Test | $45 |
| Benzene, vinyl chloride, and listed VOCs | Fuel leaks, industrial solvents, and contaminated groundwater | VOC Drinking Water Test | $150 |
| PFOA, PFOS, and other listed PFAS | Industrial pollution, firefighting foams, and contaminated groundwater | PFAS Forever Chemicals Water Test | $415 |
| Radon | Naturally occurring radioactive materials in soil and rock | Radon in Water Test | $40 |
| Lead | Service lines, pipes, and plumbing fixtures | Lead Water Test | $45 |
| THMs, 1,4-dioxane, radium, and gross alpha | Varies by contaminant | Contact ETR to confirm testing availability | Not listed |
Important: A water test only checks for the substances included in its published analyte list. If you need to check for a specific chemical, confirm that the test includes it before ordering.
To test your water for carcinogens, match the test to your source, check what it includes, collect the sample and review the results. These steps also cover how to test well water for chemicals.
Most instant home test strips are designed to measure basic water quality factors, such as pH, hardness, or chlorine. They cannot reliably identify many cancer-related contaminants at the low concentrations relevant to drinking water.
Chemicals such as PFAS and VOCs require specialized laboratory analysis. Some are measured in parts per billion or even parts per trillion.
You can still collect a sample at home using a laboratory testing kit. The difference is that the sample is sent to a lab equipped to identify and measure the specific contaminants.
Your laboratory report should show which contaminants were tested, which were detected, and their measured concentrations.
Finding a potentially carcinogenic substance in water does not automatically mean the concentration exceeds a drinking water standard. However, the result should be compared with the appropriate health or regulatory guidance.
The EPA uses two important measurements when regulating contaminants in public drinking water systems:
For some carcinogens, including arsenic and benzene, the EPA sets the MCLG at zero. The enforceable MCL may be higher because regulations also consider what can be measured and treated using available technology.
Our guide to MCL vs. MCLG explains these differences in more detail.
A detected result means the laboratory identified a substance in your sample. The report should also show its concentration and the applicable detection or reporting limit.
A non-detect result doesn't necessarily mean the substance is completely absent. It means the laboratory did not detect or report it above the relevant threshold.
Our article on water testing detection limits explains how these values affect your results.
Not every potentially carcinogenic contaminant has an enforceable federal drinking water limit.
For example, 1,4-dioxane and radon do not have federal MCLs for drinking water. However, some states have established their own guidelines or requirements.
If your report identifies a contaminant without a federal MCL, check your state health department's recommendations. You can also ask the laboratory which official guidance is appropriate for interpreting the result.
If your test shows a concentration above an applicable health-based level:
The appropriate response depends on the specific chemical, its concentration, and your water source.
No. CDC states that boiling will not remove chemicals from water, and EPA says boiling does not remove lead. Boiling is meant for germs, not chemicals, so a laboratory test is the way to learn which chemicals are in your water.
You can collect the sample at home and send it to a lab. Home strips do not detect arsenic, VOCs or PFAS at drinking-water levels, so the analysis needs laboratory instruments. Our kits include collection instructions and a prepaid return label.
Test when you buy a home or drill a well, then follow your state health department's guidance. CDC advises yearly testing for basics such as bacteria and nitrates, and asking your health department whether to add arsenic or VOCs.
No. Drinking water can contain many different chemicals with cancer-related health concerns, and they require different laboratory methods. Broad water testing panels may cover several contaminants, but no single test includes every possible carcinogen. Check the laboratory's analyte list to confirm that the chemicals you're concerned about are included.
Start with your water source and local risk. For a private well, look at geology and nearby industrial, landfill or agricultural activity, and for city water, read the Consumer Confidence Report first. Then match those concerns to specific substances instead of ordering based only on the word "carcinogen."
Only for the contaminants tested, and only down to the laboratory's reporting limits. A clean arsenic or VOC result does not prove every possible carcinogen is absent, so add testing when you have a specific reason.
ETR Laboratories offers testing for several drinking water contaminants linked to cancer, including arsenic, certain VOCs, PFAS, and radon.
You can order individual tests for specific chemicals or choose a broader panel, such as our Premium Well Water Test, to check multiple contaminants.
Every test includes a free consultation with our water quality experts to help you understand your results.
Not sure which test you need? Contact ETR Laboratories before ordering. Our team can help you check which contaminants are included and discuss available testing options.
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