Contaminants in Water: Drinking Water Contaminants and Filtration

Contaminants in water are a growing public health crisis, affecting tap water for hundreds of millions of people in the U.S. and worldwide. From PFAS and hexavalent chromium to lead and fecal bacteria, dangerous pollutants in drinking water often remain invisible, under‑regulated, and unevenly distributed. According to the World Health Organization (WHO), over 1.7 billion people globally still use drinking water contaminated with feces, which remains a leading cause of diarrheal diseases. Many of them have no taste, smell, or color. Yet they can sit in your glass every day.

You may assume your tap is safe because your water bill arrives on time and the water is “legal.” But legal does not always mean healthy. Many drinking water contaminants fall below federal limits and still exceed levels that independent scientists link to cancer, brain damage, or other long‑term health effects.

In this guide, you will learn:

What the major contaminants of water are today and how they affect health.
How to tell what contaminants are in your drinking water at home.
What makes tap water unsafe, even when it meets basic standards.
The best water treatment methods and habits to reduce your exposure.
Why some communities, especially Hispanic, Black, and low-income neighborhoods, face higher risks.

Key Facts About Contaminants in Water (At‑a‑Glance)

If you only have a minute, these numbers show the scale of tap water contamination.

Quick stats

Issue	Key data (U.S. and global)
U.S. water systems with at least one contaminant above health guidelines	Almost all public water systems (EWG analysis)
People with hexavalent chromium (chromium‑6) in tap water	~250 million Americans
People with PFAS detected in tap water	At least 143 million Americans
Lead service lines	Millions still in use across the U.S.
Pennsylvania violations	~1.8 million health‑based and ~900,000 acute violations in recent years
Massachusetts lead infrastructure	132,000+ lead pipes; 439 contaminated systems
Residents in AZ & MD with multiple toxic substances (nitrates, arsenic, chromium‑6, PFAS)	>6 million
Globally using fecally contaminated water	>1.7 billion people

The key point: “Legal” ≠ “safe.”

Regulatory limits (set under the Safe Drinking Water Act) often lag behind new science. Health‑based guidelines from public‑health researchers are usually lower than federal limits. That means your water can be legal but still carry higher‑than‑ideal risks over a lifetime.

What Are Contaminants in Water?

To put it simply, a contaminant in water is anything that is not supposed to be there at that level and can harm human health or the environment. Some are man‑made chemicals. Some are natural minerals from rock and soil. Others are living things, like bacteria or parasites.

Regulators often group drinking water contaminants into four main types:

Chemical contaminants – things like lead, arsenic, nitrates, PFAS, pesticides, industrial solvents, and disinfection byproducts.
Biological (microbial) contaminants – bacteria, viruses, and protozoa (parasites) that can cause infection and diarrhea.
Radiological contaminants – radioactive elements such as uranium and radium that come from bedrock.
Physical contaminants – sediment or particles, often a sign of other pollution.

When people ask, “What is a chemical pollution in the water?” they are usually talking about those chemical contaminants: industrial chemicals, heavy metals like lead and mercury, fertilizers and nitrates from farms, and compounds formed when chlorine reacts with natural matter. Chemically polluted water often looks normal but carries invisible substances that can build up in the body.

Where do these contaminants come from?

Common sources include:

Industrial pollution – discharges, leaks, and improper disposal of solvents, PFAS, metals, and other toxic substances.
Agricultural areas – runoff from fertilizer, manure, and pesticides adding nitrates and other chemicals to rivers and groundwater.
Aging plumbing systems – corroded pipes and solder releasing lead, copper, and other metals into drinking water.
Septic systems and sewage – leaks and failures sending coliform bacteria, E. coli, parasites, and viruses into wells and lakes.
Naturally occurring minerals in bedrock – arsenic, uranium, and manganese that dissolve from the earth’s crust into groundwater.
Water treatment byproducts – chlorine is used to make water safe by killing microbes, but it can react with organic matter to form disinfection byproducts like trihalomethanes (THMs) and haloacetic acids (HAAs).

When we talk about the 7 major types of water pollutants, we can group them this way:

Pathogens (bacteria, viruses, parasites).
Nutrients (nitrates and other nitrogen compounds).
Heavy metals (lead, arsenic, mercury, manganese).
Organic chemicals (VOCs, pesticides, PFAS).
Sediment and suspended solids.
Radioactive substances (uranium, radium).
Emerging contaminants (pharmaceuticals, hormones, microplastics, microfibers).

These categories help explain not only what the pollutants are, but also what makes water unsafe to use for drinking, cooking, and infant formula.

Major Contaminants in Water and Their Health Risks

Understanding the major contaminants in water is crucial for protecting your health. Different types of water contamination affect the body in varied ways. This section explores the most common pollutants in drinking water, their sources, and the specific health risks they pose over time.

Lead

Lead is one of the most well‑known drinking water contaminants. It is a heavy metal once used widely in pipes, solder, and fixtures. It rarely comes from the water source itself. Instead, it leaches from corroded pipes and plumbing systems, especially in homes and schools built before 1986.

Many older cities still rely on lead service lines to connect homes to public water systems. When water is acidic or has certain minerals, it can pull lead off the inside of these pipes. Disturbing old pipes during construction can also spike levels.

Lead in water has shown up across the country, including:

Massachusetts, with more than 132,000 known lead pipes.
Louisiana, where one survey found 88% of homes tested had lead in water.
New Jersey, where 56% of schools tested had lead above recommended levels.

Health effects of lead

There is no safe level of lead for children. Even very low exposure can:

Lower IQ and slow brain development.
Cause behavior and attention problems.
Increase risk of learning difficulties.

In adults, lead can:

Raise blood pressure.
Harm kidneys.
Increase risk of anemia and heart disease.
Create serious risks during pregnancy, including miscarriage and pre‑term birth.

The EPA’s Lead and Copper Rule sets an “action level” of 15 parts per billion (ppb), but this is not a true “safe” level. It is a trigger for utilities to take steps like corrosion control.

How to cut lead exposure at home

If you live in an older home or a city with known lead issues, you can:

Run the tap for several minutes in the morning or after it has been sitting, especially before using it for drinking or cooking.
Use only cold water for drinking and for making baby formula, since hot water dissolves more metals.
Install a certified filter (NSF/ANSI 53 or 58 for lead) at the tap or under the sink.
Ask your water utility if you have a lead service line and how to replace it.
Consider a blood lead test for children if you suspect past exposure.

PFAS (“Forever Chemicals”)

PFAS (per‑ and polyfluoroalkyl substances) are a large family of man‑made chemicals used to make products nonstick, waterproof, or stain‑resistant. They are also used in some firefighting foams and many industrial processes.

They are called “forever chemicals” because they do not break down easily in the environment or in the body. Once PFAS enter lakes, rivers, or groundwater, they can stay there for decades.

PFAS contamination often affects:

Communities near military bases and airports (due to firefighting foam).
Areas close to factories that use PFAS in products “used to make” coatings, plastics, or textiles.
Regions with PFAS‑laden sludge spread on farm fields.

At least 143 million Americans have PFAS detected in their tap water. Studies also show that Hispanic, Black, and low‑income communities are more likely to live near PFAS sources and other industrial pollution.

Health effects of PFAS

Different PFAS have different risks, but common effects include:

Higher risk of kidney and testicular cancers.
Changes in cholesterol and liver function.
Immune system problems, including weaker vaccine response.
Thyroid disease.
Lower birth weight and developmental problems in babies.

2024 EPA PFAS standards

In April 2024, the EPA set the first nationwide enforceable limits for several PFAS in public water systems. For example:

PFOA: 4 parts per trillion (ppt).
PFOS: 4 ppt.
A combined “hazard index” for PFNA, PFHxS, and GenX chemicals, with a level equal to 10 ppt for each when assessed together.

Utilities have several years to test and then install treatment where needed. That means PFAS will remain in many systems for some time.

Reducing PFAS in drinking water

Not every filter removes PFAS. The methods that work best include:

Reverse osmosis (RO) systems (often called “RO systems” or “RO filters”), which push water through a special membrane.
Some activated carbon filters with proven PFAS reduction.

When shopping, look for filters certified for PFAS removal. You can also reduce exposure by avoiding some stain‑resistant and nonstick products, but drinking water is a major route, so filtration is key.

Hexavalent Chromium (Chromium‑6)

Chromium is a metal that comes in several forms. Hexavalent chromium, also called chromium‑6, is the more toxic form and is a known carcinogen when swallowed over a long period.

It often reaches water supplies from:

Metal plating and other industrial waste.
Leather tanning and pigment production.
Improper disposal of industrial sludge or wastewater.

The famous Hinkley, California case (the story behind the film about a legal battle in a small desert town) involved chromium‑6 in groundwater that caused serious health problems for residents.

Today, about 250 million Americans have chromium‑6 detected in their tap water. Yet the federal drinking water standard still covers only “total chromium”, not chromium‑6 on its own.

Some states, like California, have set much lower public‑health goals for chromium‑6, far below the federal standard. This is a clear example of how legal limits can lag behind newer science.

Health concerns

Hexavalent chromium in water is linked to:

Higher risk of stomach and intestinal cancers.
Liver and kidney damage.
Skin rashes and allergic reactions.

Nitrates and Agricultural Pollutants

If you live in a rural area or near intensive farming, nitrates are one of the most important contaminants to know about.

Nitrate and nitrite are forms of nitrogen used in fertilizer for crops. They also come from:

Animal manure and large feedlots (CAFOs).
Septic systems and sewage.
Storm runoff from fields into rivers and groundwater.

Private wells in farm regions often show some of the highest nitrate levels, because they are closer to the source and not always treated. Millions of people drink water with nitrates higher than health‑based guidelines, even if still below the EPA legal limit of 10 milligrams per liter (as nitrogen).

Health effects of nitrates

In infants, high nitrates can cause “blue baby syndrome” (methemoglobinemia), where the blood cannot carry enough oxygen.
Long‑term exposure is linked to higher risk of colorectal cancer, thyroid disease, and possibly birth defects.

Nitrates often travel with other agricultural pollutants like pesticides and herbicides. Many of these are organic compounds that may affect hormones, the nervous system, or cancer risk, even at low, repeated doses.

If your home uses a private well near farms or septic systems, regular water tests for nitrates, coliform bacteria, and other common water contaminants are essential.

Disinfection Byproducts (TTHMs, HAA5, Chloroform)

Chlorine is used to kill pathogens in drinking water, which saves millions of lives. But when chlorine or other disinfectants react with natural organic matter (like decaying leaves) in water, they can form disinfection byproducts (DBPs).

The most widely measured DBPs are:

Total trihalomethanes (TTHMs) – including chloroform.
Haloacetic acids (HAA5).

Thousands of water systems have TTHMs and HAA5 at levels above health‑based guidelines. Some states, such as Pennsylvania, have high violation counts related to these DBPs.

Health risks from DBPs

Long‑term exposure to higher levels of DBPs is associated with:

Increased risk of bladder and other cancers.
Reproductive problems and possible birth defects.
Higher miscarriage risk in some studies.

This creates a balancing act: we need chlorine to kill microbes like Giardia and Cryptosporidium, but utilities must also protect source water and improve treatment to reduce DBP formation. Better filtration at the plant and at home can lower DBP levels while keeping water microbiologically safe.

Volatile Organic Compounds (VOCs) – e.g., TCE

Volatile organic compounds are chemicals that easily turn into vapors or gases. Many VOCs are used as:

Solvents and degreasers in factories.
Dry‑cleaning fluids.
Ingredients in paints and cleaning products.

A common VOC in contaminated groundwater is trichloroethylene (TCE). Industrial spills and leaking underground storage tanks can create plumes of TCE in groundwater that last for years and spread under homes.

Health effects of VOCs

Some VOCs, including TCE, are carcinogens.
Others can harm the liver, kidneys, or nervous system.
Short‑term exposure may cause headaches, dizziness, or irritation; long‑term exposure carries cancer and organ damage risks.

People on private wells near industrial areas or old gas stations should test for VOCs, because these wells are not covered by public water testing under the Safe Drinking Water Act.

Microbial Contaminants and Fecal Pollution

Chemical contamination often gets the headlines, but around the world, microbial contamination is still the biggest killer.

Globally, the World Health Organization estimates that over 1.7 billion people use water contaminated with feces. That means their main water source contains E. coli or other fecal coliform bacteria, which signal human or animal waste.

Common pathogens in unsafe water include:

Bacteria like E. coli and Salmonella.
Viruses such as norovirus and hepatitis A.
Parasites (protozoa) like Giardia and Cryptosporidium.

These microorganisms cause:

Diarrhea and dehydration.
Cholera and dysentery.
Serious illness and death, especially in young children and people with weak immune systems.

Even in the U.S., outbreaks happen after floods, sewage overflows, or treatment failures. Rural wells can be contaminated by septic systems, manure, or wildlife. Regular tests for total coliform bacteria and E. coli are critical for private wells.

Emerging Contaminants: Pharmaceuticals, Hormones, Microplastics, Microfibers

Modern life adds new emerging contaminants to our water resources. Many do not yet have enforceable standards.

Pharmaceuticals and hormones reach water when:

People flush unused drugs.
Medicines and hormones pass through our bodies and into sewage.
Animal antibiotics and hormones wash off farms into rivers.

These chemical contaminants can influence hormones in fish and may contribute to antibiotic resistance. Tests have found traces of painkillers, antidepressants, and birth control hormones in rivers and some drinking water sources.

Microplastics and microfibers are tiny pieces of plastic that come from:

The breakdown of larger plastic waste.
Synthetic clothing fibers released during washing.
Tire and road wear washed into streams.

Scientists are still studying what happens when people drink or inhale microplastics. Early research suggests they may cause inflammation or carry other chemicals into the body, but many questions remain.

Right now, most of these emerging pollutants are unregulated, though they are widely detected. That is one reason many experts say we should treat “legal” water as a starting point, not a guarantee of safety.

Health Effects of Drinking Water Contaminants

Different contaminants affect different parts of the body. Many health problems appear only after years of exposure, which makes them easy to ignore.

Neurological effects – Lead and manganese can damage the brain and nervous system, especially in children. Solvents like TCE may cause headaches, memory problems, or nerve damage.
Endocrine and metabolic effects – PFAS, some pesticides, and hormones can disturb the body’s hormone system, leading to thyroid disease, weight changes, and altered cholesterol. Nitrates may also affect how the thyroid works.
Cancer risk – Hexavalent chromium, arsenic, some DBPs (TTHMs and HAA5), VOCs like TCE, and PFAS are all linked to higher cancer risk over a lifetime. One study estimated more than 100,000 lifetime cancer cases in the U.S. could be tied to carcinogens in tap water.
Reproductive and developmental effects – Lead, nitrates, PFAS, and DBPs are linked to miscarriage, low birth weight, birth defects, or learning and behavior problems later in life.
Infectious disease – Microbial contaminants such as Giardia, Cryptosporidium, E. coli, and viruses cause acute illness, sometimes in just days or hours. In many low‑income countries, fecally contaminated water is a leading cause of child death.

You may wonder, “If this is so serious, why don’t I feel sick?”

Many water contaminants cause chronic, low‑level harm. You will not get a rash or a fever. Instead, they quietly raise the odds of certain diseases over many years. That is why reading your water test results, not just relying on taste or smell, is so important.

Who Is Most at Risk? Disparities and Hotspots

Water contamination does not hit every group the same way. Studies show that Hispanic and Black communities in the U.S. are more likely to:

Live near industrial plants and landfills that pollute water.
Rely on underfunded public water systems with aging pipes.
Face higher levels of contaminants like nitrates, arsenic, or PFAS.

Some state‑level examples:

Pennsylvania recorded more than 1.8 million health‑based drinking water violations and over 900,000 acute violations in recent years.
Massachusetts has hundreds of contaminated systems and over 132,000 lead pipes.
Louisiana and New Jersey both report widespread lead in schools and homes.
Arizona and Maryland have more than 6 million residents exposed to multiple toxic substances—nitrates, arsenic, chromium‑6, PFAS—often above health guidelines.

Private wells vs. public systems

Public water systems must meet federal standards and send annual Consumer Confidence Reports (CCRs). But private wells (common in rural areas) are mostly unregulated. Well owners are responsible for testing and treatment.

This means families on wells near farms, septic systems, or mining sites may have high exposure without knowing it, unless they order regular water tests.

How to Find Out What’s in Your Water

When people ask, “What contaminants are in my drinking water?” the honest answer is: you need data. Here is a simple path, starting with the easiest steps.

Read your annual Consumer Confidence Report (CCR).
1. If you use a public water system, your utility must mail or post a yearly report.
2. It lists detected contaminants, the highest levels found, and how they compare with EPA limits.
Use national tools to check trends.
1. The EPA’s Water Quality Indicators map shows violation history and basic contamination patterns in your area.
2. The Water Quality Portal lets you search test results for local rivers and groundwater.
3. Nonprofit databases can compare your tap water levels to stricter health‑based guidelines.
Check state and local health department data.
1. Many state departments of health publish school water testing results, lead maps, and nitrate hotspot maps.
2. Some cities list which neighborhoods still have lead service lines.
For private wells, schedule regular testing.
1. Test every year for nitrates and coliform bacteria.
2. Every 3–5 years (or after flooding or nearby construction), test a broader panel: lead, arsenic, manganese, fluoride, VOCs, and, where relevant, uranium or radium.
3. Use a certified lab and keep all results in a home water file.

In future versions of this guide, imagine using an interactive map or entering your ZIP code to see key risks like PFAS, lead, or DBPs in your area. Until then, combining your CCR, state data, and lab tests gives the clearest picture.

Regulations vs. Real Health Risks

While legal limits set by agencies like the EPA define what is “safe” for public water systems, they often lag behind the latest scientific research. Understanding the gap between regulations and real health risks helps you see why water can meet legal standards yet still contain contaminants at levels that pose long-term health concerns.

How drinking water rules work

Under the Safe Drinking Water Act, the EPA sets:

Maximum Contaminant Levels (MCLs) – legal limits for contaminants in public water.
Maximum Contaminant Level Goals (MCLGs) – ideal health goals, often lower and sometimes zero.
Action levels or treatment techniques – rules for certain contaminants like lead and microbes.

Independent groups and some states also publish health‑based guidelines, which are often stricter than federal MCLs.

“Legal” vs. “health‑based” – key examples

Values below are simplified and rounded; they are for illustration, not for medical decisions.

Contaminant	EPA legal limit (MCL or action level)	Example health‑based guideline (approx.)	Notes on health effects
Lead	15 ppb (action level)	0 ppb (goal); many experts warn above 1 ppb	Brain damage in children, hypertension, kidney harm
Nitrate (as N)	10 mg/L	~1 mg/L in some research	Blue baby syndrome, cancer, thyroid disease
Arsenic	10 ppb	0.004 ppb (CA public health goal)	Skin, bladder, lung cancers; heart disease
Hexavalent chromium	Covered in 100 ppb total chromium	0.02 ppb (CA goal for Cr‑6)	Stomach cancer, organ damage
TTHMs (DBPs)	80 ppb	~0.15 ppb (health‑based guideline)	Bladder cancer, reproductive issues
HAA5 (DBPs)	60 ppb	~0.1 ppb	Cancer and possible developmental effects
PFAS (PFOA, PFOS)	4 ppt each (new 2024 MCLs)	Near 0 ppt (health goal)	Cancer, immune and hormone effects

There are also nearly 100 unregulated contaminants found in U.S. water systems. About 27% of systems, serving around 97 million people, have at least one unregulated chemical at detectable levels. These include many PFAS variants, emerging DBPs, and other organic compounds.

So when you ask, “What makes tap water unsafe?”, the answer is not only “when it breaks a law.” Tap water can be legally compliant and still carry contaminants at levels that raise long‑term health concerns, especially for children, pregnant people, and people with chronic illness.

Reducing Your Exposure to Drinking Water Contaminants

You cannot control every pollutant in rivers and aquifers. But you can lower what comes out of your tap.

Choosing the Right Water Treatment for Your Home

Here is a simple comparison of common water treatment methods and what they are good for.

Method	Main targets	Typical use	Notes
Activated carbon filter (pitcher, faucet, under‑sink)	Many organic compounds, some DBPs, some PFAS (if certified), chlorine taste and odor	Point‑of‑use (one tap)	Good first step; look for NSF/ANSI 42 & 53 certifications
Reverse osmosis (RO system)	PFAS, nitrates, many metals (including arsenic), many VOCs, fluoride	Under‑sink point‑of‑use	Very effective; wastes some water and removes minerals
Ion exchange	Hardness (calcium, magnesium), some metals and nitrates	Whole‑house softeners or specialty units	May add sodium; sometimes combined with RO
Distillation	Most contaminants, including microbes and many chemicals	Countertop unit	Slow and energy‑intensive; leaves water very low in minerals
UV (ultraviolet)	Bacteria, viruses, parasites	Whole‑house or at tap	Kills microbes but does not remove chemicals or metals
Whole‑house carbon filter	Chlorine, some organic compounds, taste/odor	Treats all household water	Often paired with other methods for lead, PFAS, or nitrates

When you choose a home water filtration system, focus on the specific risks you face:

High lead – look for filters certified for lead reduction.
PFAS – reverse osmosis or certified activated carbon.
Nitrates – reverse osmosis or certain ion‑exchange systems.
Microbial risk (well water with coliform bacteria) – UV treatment plus filtration, or chlorination with proper control.

Check for NSF/ANSI certifications for the contaminants you care about, and follow filter replacement schedules so the system keeps working well.

Low‑Cost Habits to Reduce Risk

You do not always need a full RO system to improve safety. Simple steps can help, especially for lead and microbes:

Let the faucet run for 30–60 seconds in the morning to clear stagnant water from pipes.
Use only cold water for drinking and cooking; heat it after it leaves the tap.
Do not boil water that is high in nitrates; boiling makes nitrates more concentrated.
For infant formula, use water that is low in nitrates, metals, and DBPs—often filtered tap water is a better choice than random bottled water.
Clean faucet aerators and showerheads, where sediment and bacteria can build up.
If a boil‑water notice is issued for microbes, follow it closely, but remember that boiling does not remove chemicals.

If you want to cut both waste and exposure, consider filling a reusable bottle from a filtered tap instead of relying on bottled water. Bottled water is not always safer; it is often just treated municipal water in plastic.

Special Guidance for Vulnerable Groups

Some groups need extra care:

Pregnant women and infants – Pay special attention to nitrates, lead, arsenic, and PFAS. Ask your doctor about testing if there is known contamination.
Young children – Their brains and bodies are still developing, so they are more sensitive to metals and some chemicals. Using filtered water for drinking and cooking can sharply cut exposure.
People with weak immune systems (from illness, treatment, or age) – They are more at risk from microbial contaminants like Cryptosporidium and Giardia. A combination of good filtration and disinfection is important.
Rural well users near farms, mining, or industry – Regular water tests and targeted filtration are essential because wells are not checked by public agencies.

Industrial Pollution, Agriculture, and Accountability

Many contaminants in drinking water begin as industrial pollution or agricultural runoff:

Factories may discharge PFAS, VOCs, metals, or other chemicals into rivers or underground.
Mining and drilling can release arsenic, uranium, and other minerals.
Large farms can leak nitrates, pesticides, and manure into streams and groundwater.
Landfills and waste sites may leach a mix of organic compounds into nearby wells.

Research groups maintain lists of top industrial water polluters, ranking facilities by the health hazards they release. These tools help communities see which companies near them are most likely to affect local water supplies.

If you suspect industrial contamination, you can:

Check state environmental agency maps for permitted discharges and cleanup sites.
Attend local water board or city council meetings when treatment or infrastructure is discussed.
Report strange smells, colors, or sudden changes in water taste to your utility and health department.

Online forums and videos show many examples where grassroots groups pushed for new treatment plants, PFAS cleanup, or lead service line replacement after gathering data and speaking out. Individual action at the tap is important, but so is community pressure for cleaner water resources.

Global Perspective on Water Contamination

While much of this article focuses on U.S. tap water contamination, the global picture is even more urgent.

In many countries, the main threat is microbial contamination due to lack of safe toilets and sewage treatment. Over 1.7 billion people still use drinking water that is contaminated with feces. This drives huge burdens of diarrhea, cholera, and other infections.

At the same time, rapidly industrializing regions face growing chemical pollution from factories, mining, and uncontrolled disposal. Rivers near big cities may carry a mix of metals, organic compounds, and human waste at the same time.

Climate change adds extra stress:

Floods spread sewage, farm waste, and industrial materials into wells and reservoirs.
Droughts reduce water supplies, making contamination more concentrated and encouraging use of unsafe sources.
Wildfires can change soil and ash chemistry, leading to new contaminants in runoff.

Yet there is progress. Low‑cost point‑of‑use filters, solar disinfection, and improved chlorination are helping reduce waterborne diseases. International projects aim to bring safer water and sanitation to more people each year.

Conclusion: Key Takeaways on Contaminants in Water

Even when it is “legal,” contaminants in water often exceed levels that experts consider truly safe, and the burden falls hardest on marginalized communities and people using unregulated wells.

If you remember only a few steps, make them these:

Check your local water quality using your CCR, state data, and, if needed, lab tests.
Pay extra attention if you are pregnant, have children, or rely on a private well.
Choose filtration that matches your main risks, such as RO for PFAS and nitrates or certified carbon filters for DBPs and some metals.
Practice simple habits like flushing taps, using cold water for drinking, and avoiding boiling high‑nitrate water.
Support community efforts for lead pipe replacement, PFAS cleanup, and stronger water protections.

Safe drinking water depends on both individual choices at home and strong public systems and rules. By understanding contaminants in drinking water and acting on that knowledge, you protect not only your own household but also help push your community toward cleaner, safer water for everyone.

FAQs

1. What are the major contaminants of water?

When we talk about contaminants in water, we’re really looking at a wide variety of substances that can affect health in different ways. The major culprits include heavy metals like lead and arsenic, which often come from old pipes or natural sources; PFAS, also called “forever chemicals,” found in nonstick cookware, firefighting foams, and industrial runoff; and nitrates, mostly from fertilizers and animal waste. Disinfection byproducts like TTHMs and HAA5 form when chlorine reacts with organic matter in water. Industrial chemicals, such as trichloroethylene (TCE), can leak into groundwater from factories or old storage tanks. And of course, microbial contaminants like E. coli, Giardia, and Cryptosporidium can sneak in through sewage, failing septic systems, or stormwater runoff. The tricky part is that many water supplies contain a mix of these contaminants, so it’s not just one thing you need to watch out for—it’s the combination that can make water risky if left untreated.

2. What contaminants are in my drinking water?

If you’re wondering what’s actually in your tap, the truth is you can’t tell just by looking or tasting. The best starting point is your local Consumer Confidence Report, which utilities are required to provide annually. This report lists detected contaminants, how much was found, and how it compares to federal limits. For those on private wells, the responsibility is on you to have the water tested regularly. Labs can measure a wide range of contaminants—from heavy metals and nitrates to PFAS and microbial pathogens. Online tools and databases can give a rough idea of what’s common in your area, but nothing beats actual testing from your own water source. Remember, even water that looks clear and smells fine can still carry invisible contaminants, so relying on sensory checks alone isn’t safe. Regular testing is the only way to know for sure.

3. What are the 7 major types of water pollutants?

Water pollution isn’t just one thing—it comes in several forms that affect our health differently. There are seven main categories. First, pathogens, which include bacteria, viruses, and parasites, can cause infections or diarrhea. Next, nutrients like nitrates from fertilizer or animal waste can impact infants and long-term health. Heavy metals, such as lead, arsenic, and mercury, are toxic even at low levels. Organic chemicals, including pesticides, PFAS, and industrial solvents, can interfere with hormones or increase cancer risk. Sediment or suspended solids may seem harmless, but they often carry other pollutants. Radioactive substances like uranium or radium can occur naturally in groundwater. Finally, emerging contaminants such as pharmaceuticals, hormones, and microplastics are being detected more often, and their long-term health effects are still under study. Together, these seven types show how complex water contamination really is.

4. What is a chemical pollution in the water?

Chemical pollution in water happens when substances like industrial solvents, PFAS, pesticides, metals, nitrates, or disinfection byproducts (DBPs) show up at levels that can harm people or the environment. Unlike microbial contaminants, these chemicals often don’t make you sick immediately, so you might never notice them in your glass. But over months and years, even low-level exposure can increase the risk of chronic diseases, including cancer, liver or kidney damage, and hormonal disruptions. Many chemicals also accumulate in the body or in ecosystems, creating longer-term consequences. Sources can include old pipes, factory runoff, agricultural fertilizers, and water treatment byproducts. Because chemical pollution is largely invisible, relying on taste or smell isn’t enough—using proper filtration, testing your water, and staying informed about local contamination issues are the best ways to reduce your risk.

5. What makes tap water unsafe?

Tap water becomes unsafe not just when it tastes bad or looks cloudy—it’s about the invisible risks lurking inside. Short-term hazards like severe microbial contamination or very high nitrate levels can make water immediately dangerous, especially for babies or immunocompromised people. Long-term risks come from contaminants like lead, arsenic, PFAS, and disinfection byproducts, which may not cause obvious symptoms but can quietly raise the odds of cancer, neurological damage, or reproductive issues over years of exposure. Even water that meets federal legal limits isn’t necessarily “safe” from a health perspective, because many regulations lag behind the latest science. The key is knowing your water, testing when necessary, and using targeted filtration or treatment methods to reduce exposure. Safety isn’t just about legality—it’s about real health protection.

References

https://www.who.int/news-room/fact-sheets/detail/drinking-water

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