It may come as a surprise, but your water may not be as safe as you think. Many harmful contaminants lurk in tap and well water — sometimes at levels that far exceed what researchers consider safe. 

While the Environmental Protection Agency (EPA) sets legal limits, they don’t always align with health-based recommendations. The EPA’s Maximum Contaminant Levels are often much higher than the stricter Health Guidelines set by experts at the Environmental Working Group (EWG). Remember: legal doesn’t always mean safe.

With that in mind, let’s take a closer look at the most prominent contaminants that are currently in your tap water.

Arsenic is a naturally occurring mineral found across all 50 states that makes its way into our drinking water through natural processes, industrial waste, and agricultural runoff. 

Both the EPA and World Health Organization (WHO) classify arsenic as a “known human carcinogen” due to evidence linking exposure to an increased risk of bladder, lung, and skin cancer. The American Heart Association and other health agencies have found substantial evidence connecting arsenic exposure to cardiovascular problems. 

Studies suggest children are especially vulnerable to the dangerous effects of arsenic exposure. A 2013 study found that prenatal exposure can impair intelligence, cause behavioral problems, and weaken their developing immune system. 

Currently, the EPA’s limit for arsenic in drinking water is 10 parts per billion (ppb), but that concentration still puts many at risk. Many scientists and experts, including those at the EWG, have recommended a strict Health Guideline of 0.004 ppb to minimize cancer risk. 

Limiting arsenic in water is imperative – over 109 million Americans are drinking water with arsenic levels that exceed the EWG’s recommended limit, and that number doesn’t include those who get their water from private wells.

Manganese is a naturally occurring mineral that supports a range of important bodily functions at low doses – but in excess, it poses harm to infants and children.

Recent studies have linked manganese exposure to hyperactivity, reduced IQ scores, and memory and attention problems in children. High levels of manganese exposure may result in:

• Undesirable effects on brain development and changes in behavior 

• Decreases in the ability to learn and remember

• Severe symptoms of manganism disease including difficulty with speech and walking 

Long term exposure can result in a neurological condition called manganism. According to the Centers for Disease Control and Prevention and National Institutes of Health (CDC), manganism symptoms are similar to those of Parkinson's disease and include:

• Trembling and stiffness

• Slow movement and depression

• Mania

• Insomnia, delusion, and memory loss 

• Hearing loss

Despite these risks, the EPA has no enforceable limit for manganese in drinking water. Instead, they’ve suggested a non-enforceable guideline of 100 ppb to prevent unpleasant taste and staining. Without legal limits, manganese can be present in any amount, though experts from the EWG suggest keeping it below 100 ppb to protect the brain and nervous system.

Plastic is a nearly indestructible material that breaks up into smaller and smaller particles over time, eventually producing what we call microplastics. Their small size allows them to easily travel through waterways and other natural systems in the environment.

A recent study published in the New England Journal of Medicine links microplastic exposure to increased risk of heart attack, cardiovascular problems, and strokes. Other concerns include:

• Chemical Additives: You may already avoid BPA and other harmful chemicals in plastics, but microplastics in the water supply are harder to control. 

• Biofilms: Microplastics act as breeding grounds for harmful bacteria, viruses, and other contaminants that get carried through the water system right to your home's tap.

• Bioaccumulation: The particles can accumulate in the body and wreak havoc on our systems. Studies suggest this accumulation can lead to uptake into our circulatory systems, causing various health issues.

Microplastics are everywhere – found in human lungs, breast milk, and even placental tissue. Alarmingly, they can break down small enough to cross barriers like the blood-brain barrier, potentially exposing the brain to toxins once thought unreachable.

While some states are implementing their own testing and water quality regulations, wastewater treatment plants aren’t designed to filter out all particles and there are currently no federal regulations or limits on the levels of microplastics allowed in our drinking water.

Total trihalomethanes (TTHMs) are a group of cancer-causing contaminants formed as a disinfection byproduct (DBPs) during water treatment processes. TTHMs include four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform.

The U.S. Department of Health and Human Services found that TTHMs are reasonably anticipated to be a human carcinogen. Long-term exposure has been linked to:

• Increased risk of bladder and colon cancer

• Damage to the central nervous systems

• Reproductive issues and birth defects

Currently, the EPA allows up to 80 ppb of TTHMs in drinking water, while the EWG recommends a limit guideline of 0.15 ppb. This gap leaves millions of Americans vulnerable to the serious risks of TTHM exposure.

Similar to TTHMs, haloacetic acids (HAA5) are a group of DBPs widely considered to be the most prevalent and harmful in tap water. An EWG analysis of drinking water samples from 2017-2019 found that more than80% of Americans could be drinking water contaminated with HAA5.

Exposure has been linked to multiple forms of cancer and can harm fetal growth and development. Additional health risks linked to HAA5 include headaches, nausea, sore throat, wheezing, shortness of breath, and damage to the liver and kidneys. Long-term exposure may cause vomiting, diarrhea, and sore throat because HAA5 has the potential to burn the tissues of the human body. 

Despite these health risks, HAA5s are legally allowed in our drinking water sources up to concentrations of 60 ppb. Experts at the EWG, however, recommend reducing this limit to just 0.1 ppb due to the significant health risks associated with these contaminants.

Trichloroethylene (TCE) is a carcinogenic volatile organic compound (VOC) that was historically used in a wide range of industrial and commercial applications. It is recognized as a human carcinogen through all routes of exposure by EPA, the International Agency for Research on Cancer, and the Department of Health and Human Services. 

TCE exposure is particularly harmful during pregnancy and childhood, with links to heart defects in developing fetuses. Other health risks include:

• Kidney and liver cancer, non-Hodgkin lymphoma

• Harm to the developing fetus

• Harm to the reproductive, brain, nervous, and immune systems

• Hormone disruption

Despite the severe health implications of TCE exposure, the EPA legally allows up to 5 ppb of TCE in drinking water, though the EWG suggests that 0.4 ppb would be a better measure to protect the immune system.  

In December 2024, the EPA officially prohibited all uses of TCE to protect from the dangerous effects of TCE exposure.

Chromium 6, also referred to as chromium (hexavalent), is a naturally occurring heavy metal that is often produced as a by-product of industrial manufacturing. A recent EWG study took samples from 60,000 sources nationwide and found that 75% of those sources had high levels of this contaminant. 

Chromium 6 is extremely toxic at low levels. The WHO has categorized Chromium 6 as a Group 1 carcinogen and exposure has been linked to cancer, damage to the liver and reproductive systems, reduced body weight, and delayed skeletal development.

As it stands, the EPA’s MCL for total chromium is 100 ppb, which includes chromium 6. However, both the EWG and California Office of Environmental Health Hazard Assessment recommend a far stricter limit of 0.02 ppb to protect public health.

PFAS are a family of more than 9,000 toxic synthetic chemicals that can’t be seen, smelled, or tasted known as “forever chemicals” due to their pervasive nature, ability to accumulate in the environment, and long lasting impact tops the list of leading contaminants in your water.

PFAS exposure has long been linked to many alarming health risks including:

• kidney, testicular and breast cancer 

• thyroid disease

• high cholesterol and high blood pressure

• cardiovascular issues

• ulcerative colitis (IBD)

• liver damage

• weakened immune system 

• irritable bowel syndrome (IBS)

• hormone imbalance

PFAS exposure is especially dangerous to pregnant women, infants, and children. Here are additional health effects linked to PFAS for pregnant women and children: 

• skeletal variations (congenital disabilities)

• low birth weight

• decreased response to vaccines

• increased likelihood of miscarriage 

• preeclampsia during pregnancy

Just this year (April 2024), the EPA imposed the first national and legally enforceable standard on concentrations of PFAS in your water. The new federal limit – 4 parts per trillion (ppt) – follows a 2022 EPA advisory warning that PFAS are more toxic than previously thought and indicates that these chemicals are dangerous at virtually any level in tap water. 

While the 4 ppt limit was established with the goal of eventually eliminating PFAS from drinking water sources entirely, the EWG suggests a health guideline of 1 ppt to protect the public from the dangers of PFAS exposure.

Lead is a metal that typically enters our waterways through lead service lines. It is a potent neurotoxin that can lead to long-term, severe health issues and behavioral problems. Both the Department of Health and Human Services and the EPA recognize lead as a human carcinogenic, while the International Agency for Research on Cancer clarified that inorganic lead is likely carcinogenic.

Children are especially vulnerable to the risks of lead exposure; their still-developing nervous system and their bodies are able to absorb metals at a higher rate, leading to harmful and permanent damage. 

At low levels of exposure, lead can impair mental development, physical growth, and exacerbate behavioral problems. High levels of lead exposure can result in anemia, muscle weakness, and brain damage.    

Other health risks of lead exposure include: 

• Severe brain and kidney damage

• Increase blood pressure and hypertension

• Harm to the reproductive system

In an effort to minimize and control lead contamination in water, the EPA established the Lead and Copper Rule (LCR) under the authority of the Safe Drinking Water Act. The LCR replaced the existing MCL with treatment techniques that are implemented if lead concentrations were to exceed 15 ppb. 

Given the toxic nature of lead, the California Office of Health Hazard established a public health goal for lead at 0.2 ppb to protect against harm to children’s brains and nervous systems. This health guideline was based on studies of children showing that an increase of 1 microgram per deciliter of lead in blood correlated with a decrease of one IQ point.

In October of 2024, the Biden administration announced a new rule requiring water utilities to replace all lead pipes. The EPA estimates that the new standard will prevent health complications due to lead exposure in up to 900,000 infants and up to 1,500 premature deaths from heart disease annually.

Fluoride is a mineral that gets added into our water systems through a process called water fluoridation to improve the public’s dental health. You may be familiar with fluoride as the key ingredient in toothpaste, but did you know it is also one of the reasons why toothpaste labels warn against swallowing it. 

In small doses, fluoride helps prevent cavities and tooth decay, but long-term fluoride exposure can lead result in tooth decay and other adverse health effects. 

Health risks linked to fluoride exposure include: 

• Dental or skeletal fluorosis

• Thyroid dysfunction

• Bone health issues

• Cardiovascular problems

• Reproductive issues

Previously, the EPA established the MCL at 4 parts per million (ppm), while the Department of Health and Human Services recommends the optimal level of fluoride in water is no higher than 0.7 ppm.

However, as of September 2024, a new federal ruling has made it clear: even the 0.7 ppm level is no longer safe. This level of fluoride exposure is still a risk of reduced IQ in children, which is sufficient to require a regulatory response by the EPA under the Toxic Substances Control Act.

The contaminants on this list are likely present in your water at varying concentrations. The best way to ensure safe, clean drinking water is with a high-quality filtration system. 

Here’s the good news: Clearly Filtered’s Affinity® Filtration Technology removes up to 99.99% of 365+ contaminants, including all the ones above, so you can trust in every drop.

Don’t wait for the EPA to take action. View our lab test results and upgrade to Clearly Filtered for cleaner, safer water for you and your loved ones.