Are There Carcinogenic Contaminants in Your Tap Water?

According to a recent study, carcinogenic contaminants may be present in your tap water. But rest assured, there are ways to filter your water, keeping your family both safe and hydrated.

carcinogenic contaminants

What are carcinogenic contaminants?

We classify carcinogens as any substance that could cause cancer. And there are several carcinogenic contaminants that may be in your tap water.
In a recent study, the Environmental Working Group (EWG) discovered 22 carcinogens in U.S. tap water. These carcinogenic contaminants include:
  • Arsenic,
  • Chromium-6
  • Disinfection by-products
  • Radioactive elements
  • Volatile organic compounds(VOCs)
Based on a cumulative risk assessment, EWG found that per 10,000 people, four will have cancer over the span of their lifetime due to carcinogenic contaminants in water.
In this blog post, we'll learn more about carcinogenic contaminants. And how you can protect your home's drinking water.
Let's dive in.

Which carcinogenic contaminants could be in your tap water?


Arsenic naturally occurs in rock. And it is sometimes found as a byproduct from industry and agriculture. Scientists have discovered the presence of arsenic in the groundwater of every state. Which means everyone should be aware of the risk factors.
The Environmental Protection Agency (EPA) restricts the amount of arsenic that can exist in drinking water to 10 ppb. However, it doesn't outright ban it. On the other hand, scientists warn that even trace levels of arsenic increases the risk of cancer and other disorders.
Arsenic can cause a number of cancers. The list includes cancer of the bladder, lungs, skin, kidney, nasal passages, liver and prostate.

Hexavalent chromium

The next carcinogenic contaminant on our list is hexavalent chromium. Hexavalent chromium, or chromium-6, is a tasteless, odorless metallic element. And rocks, plants, soil, volcanic dust, ash and animals all contain this contaminant.
Chromium-6 spreads as a result of erosion.
However, chromium-6 also enters the environment in other ways. Poor storage, leakage or inefficient practices of industrial waste can all contribute to the spreading of chromium-6.
Some additional industrial uses of chromium-6 include:
  • Manufacturing steel
  • Chrome plating
  • Manufacturing pigments and dyes
  • Preserving wood and leather
  • Lowering the temperature of water in electrical power plants
Because of its dangerous health effects, the EPA sets the drinking water standard of 0.1 milligrams per liter (mg/l), or 100 parts per billion, for total chromium.
Even in small amounts, chromium-6 likely causes skin burns, pneumonia, complications during childbirth and stomach cancer.

Disinfection by-products

Let's move on and talk about the third group on our list, disinfection by-products.
In order to make drinking water safe for consumption, water utilities protect public health by ridding drinking water of harmful bacteria, viruses and other microorganisms. They do so through a treatment process called disinfection.

What is disinfection?

Essentially, disinfection kills microorganisms present in water. During the first stage, utilities use chlorine-based disinfectants as well as techniques such as ozonation or ultraviolet (UV) purification.
However, these forms of disinfection do not offer protection as the water travels from the distribution system into consumers' homes.
A secondary treatment step prevents organisms from re-growing as the water travels from the treatment plant, through the distribution system, to people's homes.

What is chlorine?

Chlorine is an oxidizing, bleaching and disinfecting agent. We use this agent to disinfect water and prevent large outbreaks of waterborne diseases. Such as Typhoid and Cholera.

How does chlorine create potentially harmful disinfection by-products?

While chlorine protects the public from dangerous water-borne illnesses, chlorine-based disinfectants create disinfection by-products.
Some of these cancer-causing chlorine disinfection by-products include: 
  • Chloroform and Trihalomethanes (THM) remain the most common type of disinfection by-products. THMs are a group of compounds that form when chlorine and chloramine react with organic matter. Such as decaying plant material present in source water. Consequently, surface waters may be especially high in organic matter, because of plants and animals living in or near the water. The EPA regulates THM at a maximum annual average of 80 parts per billion.
  • Haloacetic acids (HAA) form when disinfectants, such as chlorine or chloramine, are used to treat water and react with naturally occurring organic and inorganic matter present in source waters. The EPA regulates HAA at a maximum annual average of 60 parts per billion.
  • Bromate forms when ozone used for disinfection reacts with bromide naturally occurring in source waters. The EPA regulates bromate at a maximum annual average of 10 parts per billion.
  • Chlorite is a potential by-product of chlorine dioxide disinfection. The EPA regulates chlorite at one part per million.

Radioactive Elements

Fourth on our list are radioactive elements. Radioactive elements enter groundwater from natural deposits in the earth's crust. And human activities result in higher concentrations. Such as uranium processing and disposal, mining, gas and oil drilling or fracking.
According to the EWG, drinking water contaminated with radioactive substances can increase the risk of cancer. And may also harm fetal development.
So what radioactive elements could be in your drinking water?
  • Radium (Radium-226 and Radium- 228) is a radioactive element that occurs naturally in groundwater, as well as oil and gas extraction activities. And if ingested in high enough amounts, likely causes bone and several other cancers. The EPA has deemed the Maximum Contaminant Level (MCL) for Radium in water at 5 pCi/L.
  • Uranium is another known human carcinogen. It's a radioactive substance found in rocks, soil, air and water. Uranium enters water by leaching from soil, rocks or processing plants. The EPA set an MCL for Uranium in water at 0.030 mg/L (or ppm).
  • Strontium-90 is produced commercially through nuclear fission for use in medicine and other industries. It is also found in the environment from nuclear testing that occurred in the 1950s and 1960s. Because strontium is a metal that accumulates in the bones, radioactive strontium-90 likely causes bone cancer and leukemia. At this time, there isn't a federal drinking water standards for strontium-90.
  • Tritium is radioactive element emitted from nuclear reactors and weapons production plants. The main health risk for tritium in drinking water is cancer. However, at this time, there isn't a national drinking water standard for this contaminant.

Volatile Organic Compounds

Lastly, let's discuss Volatile Organic Compounds (VOCs). VOCs are a mixture of elements which turn into vapors or gases. These mixtures release from burning fuels. Such as wood, gasoline, natural gas or coal. And they live in consumer products such as cigarettes, paints, preservatives, disinfects and air fresheners.
VOCs are most often referred to in the context of chemicals that have the potential to affect the environment or human health. And while VOCs can be in the air, they can also enter our drinking water in a variety of ways.
Here are VOCs that could be in your tap water. Let's start by breaking them down into two different categories.


  • Carbon tetrachloride is a volatile carcinogenic solvent used in industrial chemical production and as a dry cleaning ingredient.
  • 1,4-Dioxane is a solvent classified by the EPA as a likely human carcinogen. It contaminates groundwater in many states due to industrial wastewater discharges, plastic manufacturing runoff and landfill runoff.
  • Trichloroethylene is also an industrial and commercial solvent. And as a common groundwater pollutant, it damages the immune system, harms the developing fetus and likely causes cancer.
  • Carbon tetrachloride, a volatile carcinogenic solvent, has been used in industrial chemical production and as a dry cleaning ingredient.
  • Tetrachloroethylene (perchloroethylene) is used in dry cleaning and textile processing, as a chemical intermediate and for vapor degreasing in metal-cleaning operations. Exposure to tetrachloroethylene can lead to several types of cancer. Including bladder cancer, non-Hodgkin lymphoma and multiple myeloma.


  • 1,2,3-Trichloropropane (TCP) is exclusively a man-made chemical, typically found at industrial or hazardous waste sites. It is a potent carcinogen that contaminates drinking water in agricultural regions.
  • 1,2-Dibromo-3-chloropropane (DBCP) is a pesticide fumigant that was banned during the 1970s after scientists discovered it caused sterility in men who worked with it. The chemical causes cancer in laboratory animals and may cause cancer in people.
Additionally, there are two additional VOCs that don't necessarily fit into either of these categories. They are vinyl chloride and benzene.
Vinyl chloride is a known human carcinogen used for production of polyvinyl chloride (PVC) plastics. Discharges from plastics manufacturing contaminates drinking water with vinyl chloride.
As another human carcinogen, benzene also contaminates water. Benzene releases through emissions from petroleum processing, hazardous waste landfills and underground storage tanks. When consumed in high quantities, benzene can damage blood cells and the nervous system.
The EPA has drinking water standards for 23 VOC compounds. And it requires water utilities to monitor for these compounds.
These seven VOCs include trichloropropane, 1,3-butadiene, chloromethane (methyl chloride), dichloroethane, bromomethane (methyl bromide), chlorodifluoromethane (HCFC-22) and bromochloromethane (halon 1011).
The EPA is examining both potential health risks and occurrence data when determining if these VOCs should be regulated.

How do you remove carcinogenic contaminants?

So now that we know about the harmful contaminants that could be in our tap water, how do we remove them?
Certain carbon filters reduce some of these cancer-causing contaminants. But in order to significantly reduce them, the best option is reverse osmosis.

Reverse Osmosis

So what does a Culligan® reverse osmosis system with a Total Defense Filter do? And how does it reduce harmful contaminants?
When thinking about the RO filtration process, it's helpful to break it down into four specific steps.
For the most part, all reverse osmosis systems have pre-filtration, reverse osmosis, drainage and storage stages.
First, pressurized water moves through a particle filter. This removes impurities like salt, sand and sediment.
Next, the water passes through an activated carbon filter. Which traps and removes minerals and contaminants such as chlorine, mercury, copper and pesticides. This is the pre-filtration stage.
After that, pressurized water forces its way through the semipermeable membrane. So that the smallest impurities become trapped and only water passes through. This is the reverse osmosis stage.
Finally, the discharge stage. In this stage, removed contaminants get flushed away. While the treated water moves to a storage tank.
And before the treated water reaches a faucet, it undergoes a final activated-carbon filtration. Therefore ensuring safer, better water for household use.

What contaminants does a Culligan Reverse Osmosis System with Total Defense reduce?

Most noteworthy, reverse osmosis significantly reduces the presence of lead in water. But a reverse osmosis system also reduces mercury, chromium-6, turbidity, chlorine, cysts and volatile organic compounds (VOCs).
A Culligan reverse osmosis system with Total Defense Filter reduces over 90 other contaminants.
In addition, Culligan's reverse osmosis drinking water system is certified to reduce every EPA-regulated contaminant. Which is more than 100 in total. Compared to other household water filters, its filtration power is unmatched.
And out of the 27 most common water problems and contaminants, a Culligan reverse osmosis system with Total Defense Filter removes 26. Which includes most of the cancer-causing contaminants we covered in this blog.
Such as chlorine, chloramines, bad taste/odor, barium, cadmium, calcium, copper, cryptosporidium, fluoride, giardia, hexavalent chromium, iron, lead, magnesium, mercury, MTBE (gas), nitrate, nitrite, arsenic, radium 226/228, sediment, sodium, TDS (Total Dissolved Solids), TTHM (trihalomethanes), trivalent chromium, turbidity and VOCs (Volatile Organic Compounds).


To summarize, there could be carcinogenic contaminants in your water. However, your local Culligan water expert can test your water to find the best solution for your unique needs.