Heavy Metals in Water & The Risk of Bioaccumulation

Metals. It seems almost impossible to avoid them. They occur naturally in the environment and our bodies and can be present in many food sources, dietary supplements, and even the water flowing from our taps.

Luckily, many of these metals aren’t harmful – at least in tiny doses and with minimal exposure. But the dangerous ones, specifically those that are heavy, dense, and found in the Earth’s crust, have been associated with various health problems in children and adults, often due to bioaccumulation.

But doesn’t the EPA require utilities to monitor and control levels of heavy metals in tap water to ensure they don’t exceed dangerous limits? Yes, but some inevitably fall through the cracks and contaminate drinking water supplies. (Take the lead contamination crisis in Flint, Michigan, for example.)

Fortunately, several highly effective treatment methods can filter toxic heavy metals out of your home’s water supply. But what are heavy metals exactly, and what does it mean for them to bioaccumulate? Further, why is bioaccumulation of heavy metals in our bodies a threat to our health, and how can you reduce your exposure to heavy metals in your drinking water?

What are Heavy Metals?

Heavy metals are a group of naturally occurring metallic elements in the Earth’s crust with relatively high densities, at least five times greater than water. While many of these natural elements are essential to life, some can be toxic or poisonous at low concentrations. Therefore, we should do our best to minimize exposure as much as possible.

Lead has been one of the most talked-about heavy metals in drinking water following the Flint water crisis. However, lead isn’t the only player in the toxic and dangerous game of heavy metal contamination of drinking water. Other widely known participants include arsenic, mercury, cadmium, and chromium. Less commonly, metals including iron, copper, zinc, aluminum, beryllium, cobalt, manganese, and arsenic may be considered heavy metals.

How Heavy Metals Get into Drinking Water

Millions of Americans are exposed to heavy metals daily through their drinking water. EWG data shows that arsenic was detected in water utilities serving 108 million Americans between 2017 and 2019. During that same period, cadmium and inorganic mercury were found in utilities serving 7 million and 6.3 million people, respectively. Many other discoveries have been made (far too many to list here), but this leaves us with one crucial question: How did these elements get into drinking water in the first place?

Even if water starts free of heavy metals at the source, it can be contaminated on its way to the tap. According to the EPA, household plumbing and service lines, mining operations, petroleum refineries, electronics manufacturers, municipal waste disposal, cement plants, and natural mineral deposits can leach heavy metals into the water as it journeys to your home. Heavy metals can contaminate private wells through groundwater movement and surface water seepage and run-off.

What is Bioaccumulation?

Heavy metals are significant health hazards because of their characteristic of bioaccumulating in our bodies. Bioaccumulation is the gradual buildup of chemicals – or metals, in this case – over time in living organisms. Essentially, the organism takes in the chemical substance faster than the organism can expel it, or the organism cannot fully metabolize (break down) the substances it ingests.

Heavy metals are distributed around the body through the blood when they enter the body. Depending on the metals’ properties, they may accumulate in specific body parts, such as tissues (for example, nervous and fatty tissue), bones, teeth, organs (such as the kidneys, liver, and brain), or substances produced in the body such as breast milk.

Once the metals are absorbed, the body cannot catabolize or excrete them quickly enough. Fatty mammary tissue often contains the highest concentrations of toxic metals, which can then pass to infants when nursing.

Bioaccumulation of Heavy Metals in Humans

We are all subject to bioaccumulation from consuming contaminated aquatic organisms or exposure to heavy metals in our food, air, or water. In addition to bioaccumulating, heavy metals do not biodegrade, which means they can last for a very long time in our bodies without breaking down.

The Flint, Michigan lead contamination in 2014 is a classic example of a health scare resulting from the bioaccumulation of heavy metals. The crisis occurred after the city switched its primary water source to the Flint River. Unfortunately, its water treatment systems were ill-equipped to treat a highly corrosive water supply. The Flint River water was so corrosive that it caused lead to leach from the city’s outdated lead pipes into the water supply after the water had already passed through the treatment facilities.

Lead contaminated the local drinking water supplies, exposing tens of thousands of Flint residents to dangerous concentrations. Over time, people began ingesting the metal through drinking water and other routes, causing it to build up in the body. The bioaccumulation caused an array of adverse health problems, including lead poisoning in children, reproductive issues in women, etc.

Bioaccumulation of Heavy Metals in Marine Organisms

Aquatic organisms, like fish, are especially susceptible to bioaccumulation because they absorb contaminants from the water around them faster than their bodies can excrete them. For example, when mercury enters waterways and lakes through industrial processes, fish and shellfish absorb it directly from the environment. Although they may only absorb small amounts at a time, the mercury can remain in the fish’s body for months and even longer. This leads to mercury building up or bioaccumulating in the fish’s body, posing a danger to any organism (including humans) that eats the fish.

An example of an environmental disaster involving heavy metals – specifically mercury – occurred in 1932 in Japan. Sewage containing mercury was released into Minamata Bay. The mercury accumulated in the marine life, eventually leading to mercury poisoning in the population. The mercury poisoning was so severe that it caused people to develop a neurological syndrome called Minamata disease.

Health Effects of Heavy Metal Exposure

Heavy metals can have dire consequences for the health of humans when ingested. The effects are especially harmful to babies, young children, people with weakened immune systems, and the elderly. Many heavy metals play a role in cancer development or cause internal damage, even at low concentrations.

We’ve outlined several heavy metals commonly detected in drinking water and summarized their known health effects.


Although arsenic is considered a metalloid, it can produce the same level of toxicity as heavy metals. Arsenic exposure can cause a broad range of adverse health complications, including lung and skin cancer, decreased IQ, nervous system issues, breathing problems, and even death in high doses.

Learn more: The 12 Most Dangerous Contaminants Found in America’s Water Supply


Lead is one of the most dangerous heavy metals detected in drinking water, even at low doses. When ingested over time, it can accumulate in the body and have several toxic effects on your bones, brain, kidneys, and liver. It can also cause anemia, reproductive issues, and renal impairment. Children are especially vulnerable to the harmful effects of lead poisoning. Early childhood lead exposure can lower a child’s IQ, negatively impact their behavior, and result in lifelong disabilities.

Learn more: How Lead in Water Affects Children and Adults


Mercury and its compounds affect the central nervous system, kidneys, and liver. They can also disturb immune processes, cause tremors, impaired vision and hearing, paralysis, insomnia, and emotional instability. More often, mercury poisoning builds up over time. However, a sudden onset of these symptoms could indicate acute toxicity.


Originally found in rechargeable batteries, cameras, mobile phones, and other everyday electronics, cadmium can remain in the human body for decades once ingested. Long-term exposure to this metal is linked to renal dysfunction, bone defects, and lung disease, which may eventually become lung cancer.


While manganese is an essential nutrient in the body, exposure to high concentrations over many years is associated with forgetfulness, hallucinations, and damage to the nervous system. Manganese can also cause Parkinson’s, lung embolism, and bronchitis. When men are exposed to manganese for longer, they may become impotent.


Like manganese, small amounts of copper are essential to our health. However, too much of it can cause stomach cramps, vomiting, and diarrhea, especially in young children. Copper has also been linked to liver and kidney disease.


Chromium is a dangerous carcinogen, meaning it can cause cancer. People exposed to high levels of chromium are more likely to suffer lung, nasal sinus, and other cancers. Chromium is also linked to male infertility, stunted development in children, skin and eye irritation, asthma, nasal ulcers, convulsions, acute gastroenteritis, and damage to the liver and kidneys.

Learn more: 7 Potential Cancer-Causing Contaminants in Tap Water


The most common symptom of nickel exposure is skin irritation. Roughly 10-20% of Americans are sensitive to nickel and may experience a rash or other dermal irritation after showering or bathing with nickel-tainted water. However, in high doses, nickel can increase the risk of cancer in humans. Lower doses can lead to decreased lung function and allergic reactions.


Although current research and literature remain inconclusive, aluminum has been tied to various neurological disorders, including Parkinson’s disease, Lou Gehrig’s disease (ALS), and Alzheimer’s disease. On the less severe side, exposure to aluminum may have milder, shorter-lived symptoms, including nausea, vomiting, diarrhea, mouth ulcers, skin ulcers, skin rashes, and arthritic pain.

Testing Your Drinking Water for Heavy Metals

Though these health effects might seem frightening, there are a few simple ways to determine if any heavy metals or other contaminants are lurking in your drinking water.

As we mentioned earlier, lead isn’t the only heavy metal that could be in your tap water. It can also contain other heavy metals, such as mercury, arsenic, and copper, and environmental pollutants, like pharmaceuticals, herbicides, and pesticides. It may also be tainted with toxic chemicals, such as PFAS, chlorine, and chloramine.

You can find out what specific contaminants are in your water by searching online for a Water Quality Report for your area or contacting your local government. You can also purchase a water test kit and get your water evaluated for contamination by a certified laboratory. You’ll then need to find a water filter system that removes the heavy metals and other contaminants that can negatively affect your health or the taste of the water.

How to Filter Heavy Metals from Drinking Water

Reverse osmosis (RO) filtration is one of the most effective treatment technologies for removing heavy metals from water. RO water filters can treat many heavy metals in water, such as chromium, copper, lead, and arsenic.

RO technology uses added pressure to push water through a semipermeable membrane, blocking pollutants larger than 0.0001 micrometers from passing through. Removal rates depend on several factors, including the post- and pre-treatment steps, but RO removal efficiencies are high for metals, with upwards of 99.4% removal for metals like cadmium and copper.

Our under-counter point-of-use RO water filter systems are the perfect solutions for filtering heavy metals such as lead, fluoride, and arsenic from water. They fit perfectly under almost any size kitchen sink, delivering clean, healthy water every time you turn on the tap and up to 75 gallons per day.

Learn more: The Best Water Filtration Systems for Your Home

Final Thoughts

Metals are all around us. They are present in air, soil, food, water, and even our bodies. While many of these metals are vital to our health in small doses, repeated exposure can cause them to build up in our bodies through bioaccumulation.

The bioaccumulation of heavy metals in humans can lead to various adverse health problems, including cancer, diabetes, neurological issues, and damage to the nervous system, to name a few. Luckily, it’s easy to determine if tap water contains these contaminants. You can either check your water quality report for recent contamination or send a water sample from your tap to a certified laboratory for testing.

If your water contains heavy metals, we recommend installing a reverse osmosis filter to eliminate them, thereby protecting yourself and your family from any danger they may pose.

To learn more about how reverse osmosis filters can remove heavy metals and other pollutants from water and reduce the risk of bioaccumulation, our team of water experts is always here to assist.