Carcinogens in Drinking Water: Is Your Water Raising Your Cancer Risk?

For many of us, the word cancer alone is enough to evoke feelings of fear, unease, and worry. To reduce our risk, we try to make lifestyle changes, like quitting smoking, exercising regularly, and eating a healthy diet. But rarely do we consider filtering our drinking water. What does water have to do with cancer, you ask? Two words: cancer-causing contaminants.

A recent study by the Environmental Working Group (EWG) declares that Americans are drinking water containing cancer-causing contaminants and that the contamination could result in more than 100,000 cancer cases. As if that wasn’t bad enough, a cumulative risk analysis by the University of Illinois at Chicago found that U.S. counties with the highest pollution rates also have higher cancer rates, suggesting that contaminated drinking water likely plays a role.

No need to panic, though. This post explains everything you need to know about carcinogens in drinking water, including their possible health effects, testing methods, and how to minimize your risk.

What are Carcinogens?

A carcinogen is anything that can cause you to develop cancer. It may be a particular virus, a substance in the air, an ingredient in a personal care product, or a chemical in food, drinks, and even water.

But just because you come in contact with a carcinogen doesn’t mean you’ll get cancer. Your chance of getting the disease depends on many factors, including your genetic background, exposure to specific environmental factors, and the amount and duration of exposure.

The latter is one reason carcinogens in water are so dangerous. We use water every day for cooking, drinking, and preparing beverages. But since many cancer-causing chemicals have no smell, color, or taste, they are nearly impossible to identify without a test.

Unfortunately, this means you could spend your lifetime ingesting multiple carcinogens in your drinking water without realizing it. The more cancer-linked chemicals you consume through water – and the longer you drink them – the greater the chance of getting sick from them.

The Link Between Drinking Water and Cancer

By itself, tap water doesn’t pose a threat to human health. The danger lies in what’s inside the water. Now and then, cancer-causing contaminants can invade public and private drinking water systems and contaminate them.

Most U.S. public water systems rely on surface water to keep taps flowing. For those systems, contamination risks increase during drought since there’s less water to dilute contaminants, which leads chemicals to concentrate in surface water. In addition, manufacturing and industrial plants release enormous amounts of carcinogens into surface water. These chemicals may eventually end up in home water supplies if the water treatment facility does not remove them.

Private groundwater systems have the highest risk of contamination because they’re often located in areas lacking the funding and infrastructure to eliminate pollutants. There’s also the threat of industrial waste entering groundwater. But here’s the real kicker: the Environmental Protection Agency (EPA) doesn’t regulate private wells, so there’s no telling what’s entering home water supplies connected to underground wells.

So, while the water flowing from your tap might seem perfectly safe to drink, cook with, wash fruits and veggies, and prepare beverages, there’s a good chance it is tainted with chemicals linked to various cancers.

Carcinogens Found in U.S. Drinking Water

Among the scores of cancer-linked contaminants in U.S. tap water discovered by EWG scientists, a few are far more prevalent and dangerous. Below we highlight these cancer-causing chemicals, their origin, and their potential dangers.

Hexavalent Chromium (Chromium-6)

Famously known as the “Brockovich” carcinogen, hexavalent chromium, aka chromium-6, is one of the most widespread and hazardous carcinogens found in U.S. drinking water.

A new report from the EWG revealed that this carcinogen contaminates tap water serving 251 million Americans across all 50 states, Puerto Rico, the Northern Mariana Islands, and Guam, from 2013 to 2019. The report also says that concentrations of the chemical exceeded levels scientists consider safe.

The updated EWG map includes 918 new detections of chromium-6 in California since the map’s last release in 2016. In January 2022, researchers at the University of California, Berkeley, and the Los Angeles University of California, discovered that 371,000 Californians are drinking water that may contain high levels of chromium-6.

The presence of chromium-6 in drinking water can be due to natural occurrences in mineral deposits and groundwater or industrial pollution. Because the chemical is produced in massive quantities at industrial and manufacturing plants, contamination often originates from the improper disposal of industrial wastes into surface waters, especially those created during the manufacturing of wood and textiles products, stainless steel, and chrome metal plating.

Inhaling chromium-6 particles increases the risk of lung cancer and cancers of the paranasal sinuses and nasal cavity. However, ingesting it through tap water can cause stomach cancer, reproductive problems, liver damage, and problems with children’s brain development.

While the EPA classifies chromium-6 as a known carcinogen, there are no federal rules to limit the chemical in drinking water. California was the first state to set a legal limit for chromium-6 at 10 parts per billion (ppb). However, 10 ppb is 500 times the state’s public health goal of 0.02 ppb. As a result, California’s legal limit was still insufficient to protect residents against the toxic effects of the chemical.


Like chromium-6, arsenic is a potent carcinogen and a notorious poison in U.S. drinking water. Data from the EWG Tap Water Database shows that between 2017 and 2019, 108 million Americans received arsenic-tainted water that exceeded the California public health goal. These estimates don’t include people who get their drinking water from private wells that might have unsafe levels of arsenic. It’s a sad situation.

Arsenic in drinking water originates from natural, industrial, and agricultural sources. Usually, it leaches from rocks into groundwater used for drinking or irrigation. However, some industries release thousands of pounds of arsenic into the environment yearly due to waste from metal production, coal power plants, mining, and burning fossil fuels. Elevated levels of arsenic in water may come from certain fertilizers used on the soil in the past.

According to the National Cancer Institute, “prolonged ingestion of arsenic-containing drinking water is associated with an increased risk of bladder cancer and skin cancer, and medical exposure to arsenic has been associated with skin cancer in epidemiological studies. In addition, cancers of the lung, digestive tract, liver, kidney, and lymphatic and hematopoietic systems have been linked to arsenic exposure.” Other studies have found that ingesting arsenic may cause changes to the heart and blood vessels and heighten the risk of diabetes, heart disease, and stroke.

The legal limit for arsenic in drinking water is 10 ppb. However, scientists warn that this limit does not fully protect against the risk of cancer due to arsenic exposure.

Disinfection Byproducts (DBPs)

If your drinking water comes from a municipality, it’s most likely treated with chlorine before the water reaches your home. Chlorine remarkably prevents microbial contamination in water and protects people from potentially deadly waterborne diseases and illnesses such as cholera and dysentery. However, when chlorine and other chemical disinfectants react with plant and animal waste in drinking water supplies, they can create hundreds of potentially dangerous compounds collectively known as disinfection byproducts (DBPs).

Various DBPs have been detected in public water supplies serving 250 million Americans. These byproducts include:

Trihalomethanes (THMs)

THMs are a byproduct of chlorine reacting with naturally occurring dissolved organic matter in water. THMs are among the most dangerous DBPs created by chlorine in drinking water.

Research shows that drinking water with THMs or inhaling them can lead to serious health complications, such as an increased risk of kidney and liver cancer, issues with the central nervous system, heart, kidneys, and liver, stillbirths, and congenital disabilities.

Inhaling THMs and chlorine can be more dangerous than consuming them because both chemicals convert into vapor at very low temperatures. Therefore, showering or bathing with chlorinated water can increase exposure to these toxic byproducts.

The EPA has set national legal limits of 80 ppb for total trihalomethanes. However, these standards were negotiated based on the technical feasibility and cost of water treatment and did not consider the long-term toxicity of these contaminants.

DBPs formed due to wildfires

Beyond fatalities, air pollution, and destruction to vegetation and property, wildfires pose another grave threat: ashy topsoil sludge polluting rivers, streams, lakes, and reservoirs that supply public drinking water utilities.

Wildfires often burn topsoil and leave behind ash, sediment, and debris amid the ruins. The fierce blaze can also disrupt the soil’s binding ability and burn away vegetation that holds the soil in place, thus destabilizing the soil and increasing the risk of runoff during a heavy rainstorm.

Due to the soil’s instability, rainstorms can flush vast quantities of ash, sediment, nutrients, and contaminants into nearby surface water. Since most municipalities extract water from these sources, they’d need to filter out the bad taste and dirt in the water. But it can be challenging to filter out the charred micro-organic compounds in the pre-treated water because they are so small.

Unless removed, the organic compounds from the ash can combine with the chlorine used to purify the water. Not only do the compounds give the water a funny taste and smell, but they can form byproducts that can function as carcinogens with long-term exposure. It’s a recurring nationwide issue that scientists and water managers are concerned about. Still, they are studying it closely to determine effective prevention methods.

Per- and Polyfluoroalkyl Substances (PFAS)

Per- and Polyfluoroalkyl Substances, more commonly known as PFAS or forever chemicals, have been getting a lot of media coverage lately – and not for the reasons we’d prefer. PFAS chemicals have been cropping up in drinking water in cities across the U.S., posing a more significant threat to human health than previously thought.

PFAS is a family of almost 5,000 synthetic chemical compounds. Because of the strong bond between the carbon and fluorine atoms in these chemicals, they don’t break down quickly. For this reason, they can stick around in the environment and accumulate in our bodies for decades, hence the name “forever chemicals.”

Scientists at the EWG believe that some PFAS chemicals are likely present in almost all water supplies in the U.S., especially in areas where facilities handle PFAS, like manufacturing plants and wastewater treatment facilities, are located. And that’s precisely the case, according to several studies.

The EWG estimates that water supplies serving over 200 million Americans contain PFAS. In addition, 43 million Americans in more than 2,000 communities are exposed to PFOA and PFOS in their drinking water at levels above new EPA health advisories.

PFAS are toxic at low levels and have been linked to severe health problems, including increased risk of cancer and harm to the reproductive and immune systems. The most infamous PFAS chemicals, PFOA and PFOS, were phased out in the U.S. under pressure from the EPA after revelations of their hidden hazards, namely:

  • Testicular, kidney, liver, and pancreatic cancer
  • Endocrine disruption
  • Increased cholesterol
  • Low birth weight
  • Weakened childhood immunity
  • Reproductive problems
  • Weight gain in children and dieting adults

The EPA’s updated interim lifetime health advisories (LHAs) for PFOA and PFOS are 0.004 and 0.02 parts per trillion (ppt), respectively. The agency also provided final LHAs for two other common PFASs, GenX and perfluorobutane sulfonic acid (PFBS), at 10 ppt and 2000 ppt, respectively.

Volatile Organic Compounds (VOCs)

You might be aware of Volatile Organic Compounds (VOCs) if you have discussed selecting paint for your home. However, you probably didn’t know they can contaminate your drinking water and potentially increase your cancer risk.

VOCs are a group of organic chemicals with high vapor pressure and low water solubility. They are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry-cleaning agents. However, a recent U.S. Geological Survey (USGS) study found that VOCs are present in one-fifth of the nation’s water supplies.

If your drinking water has a high VOCs concentration, it’s most likely one of three contaminants: trihalomethane, perchloroethylene (PCE), or methyl tert-butyl ether (MTBE). Due to human activity, most of these and other VOCs enter drinking water supplies. For example, improper disposal of VOCs can cause the chemicals to leach into the ground and contaminate groundwater. Once they’ve infiltrated the groundwater, they can also migrate from aquifers to lakes and reservoirs, contaminating them.

VOCs can also enter drinking water from fires burning plastic water pipelines in homes connected to municipal water distribution systems, releasing hazardous volatile organic carbon into the water distribution network. A comparable situation occurred following the Tubbs Fire in an urban area of California, where up to 40 milligrams per liter of benzene, a known carcinogen, was reported in water distribution lines.

According to the EPA, VOCs are linked to various health problems, including loss of coordination, irritation of the eyes, nose, and throat, nausea, and headaches. Prolonged exposure can cause damage to the liver, kidneys, and central nervous system. Scientists are still unsure whether VOCs are carcinogenic as some organics have manifested as cancerous in animals, and some are suspected of causing cancer in humans.

The EPA has drinking water standards for 23 VOCs and requires water utilities to monitor for these compounds. However, seven VOCs are not currently regulated.


Nitrate in drinking water can be dangerous, especially for pregnant women and infants. It occurs naturally in the environment but is also found in many fertilizers used on yards, golf courses, and crop fields. Due to its widescale use in farming, the chemical is ravaging drinking water quality in many parts of America, mainly in agricultural areas.

Nitrate mainly enters the water supply through agricultural and urban runoff and discharges from wastewater treatment plants and septic systems. Approximately half of all applied nitrogen drained from farms contaminates surface water and groundwater. Hence, nitrate concentrations in drinking water are likely to increase significantly.

According to an environmental advocacy group, millions of tons of nitrates are released into America’s drinking water yearly from industrial farming, causing thousands of cancer cases and other health complications. Nitrate is also common in private wells. But since the federal government does not monitor private well water, it falls on the individual homeowner to test their well water.

High nitrate levels in drinking water have been linked to colon, kidney, ovarian, and bladder cancers. Researchers from the EWG say the chemical is responsible for 12,600 cancer cases a year. Of course, the risk varies from region to region, but many small farming communities have the highest nitrate levels in the water, thus the highest risk.

The EPA suggests a nitrate limit in drinking water at 10 mg/L. The EWG has defined a lower health guidance level for the chemical at 5 mg/L, based on studies by scientists at the National Cancer Institute and other independent researchers. These health guidelines are believed to protect against cancer and other health hazards. However, in 2015, 7 million Americans received tap water with levels higher than 5 mg/L.


1,4-Dioxane is an industrial solvent the EPA classifies as “a likely human carcinogen.” This chemical contaminates groundwater in many states due to hazardous industrial wastewater discharges, plastic manufacturing runoff, landfill runoff, industrial spills, and releases from municipal wastewater plants.

According to studies, 1,4-dioxane contaminates drinking water supplies for 90 million Americans. In 2013, the EPA classified 1,4-dioxane as a carcinogenic pollutant. Low-level lifetime exposure to the solvent can increase the risk of cancer. Higher exposure to the chemical over a shorter time is associated with irritation of the lungs, liver, gall bladder, and respiratory system.

Although no national drinking water standard exists for 1,4-dioxane, the EWG defined a health guideline of 0.35 ppb. Several states have also set their own criteria.

Radioactive Elements

When you think of “radioactive elements” or “radionuclides,” cancer is likely the first thing that crosses your mind. Radioactive elements produce a form of radiation called “ionizing.” Ionization radiation interacts directly with the molecule atoms in the DNA, preventing the cell from reproducing and damaging the cell so severely that the cell dies. It’s no wonder why the EPA has classified all ionizing radiation as “known to cause cancer in humans.”

While federal law requires water companies to monitor radioactivity levels in drinking water systems that serve more than 25 customers, EWG’s Tap Water Database reports that more than a dozen different radioactive elements are detected in American tap water serving 165 million people.

Radium, uranium, beryllium, strontium, and tritium are the most detected in U.S. drinking water. Some or all these radioactive elements enter groundwater from natural deposits in the earth’s crust. They can also be found in higher concentrations when human activities such as gas and oil drilling, uranium processing and disposal, mining, or fracking unearth these elements from the rock and soil.

Diverse types of radioactive elements may have varying health effects, but they are all associated with a higher risk of cancer. Radium, for example, is most strongly associated with bone cancer but may also cause cancer in other body parts. Uranium is known to cause kidney damage and bone and liver cancer. Strontium-90 is stored in the bones and is linked to bone cancer and leukemia. Recent research also finds that radioactive substances may damage the nervous, immune, and endocrine systems.

The EPA has established maximum contaminant limits for radioactive elements in drinking water. These limits are as follows:

  • Radium: 5 pCi/L (picocuries per liter, a unit of measure for levels of radiation)
  • Uranium: 30 µg/L or 0.030 mg/L (or ppm)

Are You Exposed to Carcinogens in Your Drinking Water?

Whether your drinking water comes from a municipality or a private well, it likely contains carcinogens. Unfortunately, you can’t always tell if there are cancer-causing chemicals in your water by looking at it, smelling it, or tasting it.

The best way to determine if your drinking water is tainted with toxic carcinogens is to:

  • Get your water tested by a certified laboratory. You can send a water sample from your tap to a local laboratory for rigorous testing for more accurate results. Depending on the laboratory, this method can be costly and time-consuming. Still, it’s a great way to know if your water is tainted with cancer-causing chemicals and perhaps what specific chemicals are present. When you purchase a water test kit from Springwell, it has clear instructions for collecting the water sample from your tap and sending it to the corresponding laboratory. The test results should be ready within a few days.
  • Check your water quality report. You can contact your local water provider and request a copy of their latest water quality report. After receiving the document, read it to see if there have been any recent carcinogen contamination reports in your area’s water supply.
  • Check EWG’s Tap Water Database. The EWG’s Tap Water Database provides valuable water quality information about a particular city or state based on the ZIP code you enter. It displays the water utility’s details, such as its location, the estimated number of people served, the period for which the data is available, and the source (groundwater or surface water). The tool will also tell you the total number of contaminants detected in the water supply and how many of them exceed EWG health guidelines. So, punch in your city or ZIP code and see if any carcinogenic contaminants are reported in your water supply.

How Can I Reduce My Exposure to Carcinogens in Drinking Water?

So far, you’ve learned about the various carcinogens in drinking water and the devastating effects they can have on human health. You’ve then had your water tested for traces of the chemicals. Great! Now, if the test results indicate that your water contains cancer-causing chemicals, how do you limit exposure to them?

You might be thinking, “Why not just stack up on bottled water and avoid drinking tap water altogether?” That’s not a good idea because bottled water is not always of better quality. Aside from introducing microplastics into the environment and water sources, bottled water costs more, consumes more energy, and endangers the environment. As a result, Springwell recommends filtering water at home as the better choice for getting clean, carcinogen-free water.

A carbon filter can help reduce the levels of some cancer-causing chemicals in tap water. For example, the Springwell CF1 Whole-House Water Filter System uses carbon filtration and an array of state-of-the-art features and technologies to remove 99.9% of contaminants from drinking water, including PFAS, pesticides, herbicides, chlorine, chloramine, haloacetic acids, THMs, etc.

However, reverse osmosis systems like our SWRO Under-Counter Reverse Osmosis Filters can remove additional cancer-linked contaminants. Although the SWROs treat water at a single faucet, they use a robust 4-stage filtration process to eliminate toxic pollutants from your water. These contaminants include arsenic, mercury, lead, chlorine, chloramine, chlorine byproducts, pesticides, herbicides, iron, aluminum, etc.

For help choosing the right water filter system to remove carcinogens in drinking water, please call us at 800-589-5592 or drop us a message today!

Final Thoughts

No American should have to settle for low-quality drinking water that endangers their health. We’re already dealing with the risk of cancer and other health problems from the foods and beverages we consume and exposure to everyday products, so our drinking water – the thing we rely on the most to keep us healthy and hydrated – should be free of contaminants that could raise our risk of cancer.

Carcinogens in water – PFAS, chromium-6, radioactive elements, nitrates, etc. – are extremely dangerous and should be nowhere near your drinking water. But thankfully, Springwell Water Systems have the best solutions to help limit your exposure to toxic chemicals and contaminants in drinking water while meeting your individual needs.