Most Common Drinking Water Contaminants: Ultimate 2023 Guide

We independently review everything we recommend. If you buy through our links, we may earn a commission. Learn More.
Common Drinking Water Contaminants

It’s more important than ever to know the most common drinking water contaminants that can affect your health. Contaminants in tap water can come from various sources and may pose significant health risks to both short-term and long-term well-being. By understanding this issue, you can take appropriate measures to protect yourself and your family from the potential dangers associated with water contamination.

In the following sections, you’ll learn more about specific contaminants and how to identify and address them to ensure safe drinking water.

Types Of Drinking Water Contaminants

Drinking water contamination is a serious public health issue that can result from various natural and human-made sources. Here are different types of drinking water contaminants that you should be aware of:

Biological Contaminants

Biological contaminants, also known as microbes or microbiological contaminants, are organisms present in the water. If consumed, these organisms can cause illnesses like diarrhea, stomach cramps, or more severe symptoms. To protect yourself, properly maintain your private well and filtration systems. The most common microbial contaminants include:

Bacteria In Water
  • Giardia: Single-celled parasite causing diarrheal illness transmitted through contaminated water or food.
  • Cryptosporidium: A parasite causing gastrointestinal illness transmitted through contaminated water or food.
  • E. coli: Bacteria causing foodborne illnesses are transmitted through contaminated food or water, even septic tanks on private wells. Symptoms include diarrhea, abdominal cramps, and vomiting.
  • Legionella: Bacteria causing severe respiratory illness known as Legionnaires’ disease, commonly found in water systems.
  • Coliform bacteria: A group of natural bacteria used as an indicator of water quality, its presence can indicate fecal contamination and the potential presence of harmful pathogens.

Heavy Metals Contamination

Natural sources of water can contain heavy metals. These metals can leach into water sources from plumbing, rocks, and soil and can cause serious health problems if ingested over time. If your tap water is discolored or has a metallic taste, you should test your water. Examples of chemical contaminants are the following:

Heavy Metal Contamination In Water
  • Lead: A toxic metal that can enter tap water through corroded pipes, plumbing fixtures, and solder. Contamination can come from your home’s plumbing or the water system lead service lines. Long-term exposure to lead can cause developmental delays in children and other health problems.
  • Copper: A metal that can enter drinking water through corroded pipes and plumbing fixtures. High levels of copper found in tap water can cause gastrointestinal problems and liver damage.
  • Aluminum: Aluminum is commonly used in the water treatment process to treat turbidity and harmful microorganisms. Exposure to high levels can lead to aluminum toxicity.
  • Arsenic: A naturally occurring element found in rocks and soil. When groundwater passes through these rocks and soil, it can pick up arsenic, leading to the contamination of drinking water sources.
  • Chromium: A metal that can enter drinking tap water through industrial pollution. Exposure to high levels of chromium can cause respiratory problems, skin irritation, and cancer.
  • Mercury: A toxic metal that can enter drinking water through industrial pollution or contaminated fish. Exposure to high levels of mercury can cause neurological problems and other health issues.
  • Iron: A naturally occurring element that can enter drinking water through natural deposits or corroded pipes. High levels of iron in tap water can cause staining of clothes and fixtures, as well as gastrointestinal problems. Elevated iron levels are especially common in well water.
  • Manganese: A naturally occurring element that can enter corroded pipes and contaminate drinking water. High levels of manganese in tap water can cause neurological problems and other health issues.
  • Fluoride: A chemical added to some municipal water sources to help prevent tooth decay. While it can be beneficial in small amounts, exposure to high levels of fluoride can cause dental fluorosis, skeletal fluorosis, and other health problems.
  • Nitrates & Nitrites: Nitrate is a naturally occurring compound found in soil and water. It can get into groundwater when fertilizer or manure is applied to crops or when wastewater from septic tanks leaches into the ground.

Disinfectants And Disinfection Byproducts

Besides heavy metals, disinfection chemicals are also part of chemical contaminants found in drinking water. Examples of these are:

Water Disinfectant
  • Chlorine: A chemical disinfectant used to kill microorganisms in water treatment, but high levels can produce an unpleasant taste and harmful byproducts.
  • Chloramine: A chemical disinfectant formed by combining chlorine and ammonia is used as an alternative to chlorine, or secondary disinfectant, in some water treatment systems. Exposure to high levels can cause skin irritation and other health problems.
  • Trihalomethanes (THMs): The most common group of disinfection byproducts, which is formed when disinfectants react with organic matter in water. Trihalomethanes can be harmful to human health with long-term exposure associated with increased risk of cancer and other health problems.
  • Haloacetic Acids: A relatively new disinfection byproduct, the most common haloacetic acid compound found in drinking water is HAA5.
  • Chloroform: The first detected DBP in water in 1974, chloroform is a known carcinogen that can also affect the central nervous and reproductive systems.

Physical Contaminants

Physical contaminants are materials or substances that are visible to the naked eye and can be present in water. Some examples of physical contaminants in water include:

  • Sediment: Soil, sand, or other particles that can enter the drinking water supplies through erosion or land runoff.
  • Debris: Leaves, sticks, or other organic matter that can enter the water supply through stormwater runoff or other sources.
  • Soil erosion: Eroded soil or sediment can enter waterways due to natural disasters, construction, or other activities, which can impact water quality and aquatic life.

Radiological Contaminants

Radiological contaminants are substances that emit ionizing radiation and can be present in water. These contaminants can come from natural sources such as rocks and soil, or from human-made sources such as nuclear power plants, mining, and radioactive waste disposal sites. Examples of radiological contaminants in water include:

  • Radionuclides: These are radioactive elements found in your tap water. This occurs naturally in rocks and soil. Long-term exposure to radionuclides may increase your risk of developing certain types of cancer. 
  • Radon: A naturally occurring radioactive gas that can dissolve in groundwater. When this water is used for drinking, it can lead to long-term exposure to radiation.
  • Uranium. A naturally occurring element that can be found in rocks and soil and can enter water sources through erosion or mining activities.
  • Strontium-90: A radioactive isotope that can be produced by nuclear power plants and can enter water sources through wastewater discharge or accidental releases.
  • Cesium-137: A radioactive isotope that can be produced by nuclear power plants and can enter water sources through accidental releases or wastewater discharge.

Volatile Organic Compounds

Volatile Organic Compounds, or VOCs, are a collection of organic chemicals that possess a high vapor pressure at standard room temperature and are prone to evaporating into the air. These compounds have a vast range of applications, including in industrial processes, consumer products, and construction materials. These include:

Chemical Contaminants
  • Benzene: Benzene is a known carcinogen that is commonly used in gasoline, plastics, and synthetic fibers production.
  • Toluene: Used in paints, coatings, and adhesives.
  • Xylene: Used in the production of plastics and synthetic fibers, as well as in the printing and leather industries.
  • Vinyl Chloride: Used in plastic products like PVC plumbing or packaging materials. Vinyl Chloride is highly flammable and poses a human health risk. The EPA limit is 0.002 mg/L of water.
  • Formaldehyde: Used in the manufacturing of building materials, such as particleboard and plywood, and in some consumer products, such as adhesives and cosmetics.
  • Trichloroethylene: Used as a solvent in many industrial processes, such as metal degreasing and dry cleaning.
  • Perchloroethylene: Used in dry cleaning and in the production of some plastics.
  • Methylene chloride: Used in the production of some plastics and as a solvent in paint strippers and other industrial processes.

Hard Water Minerals

Hard water is water that contains high levels of dissolved minerals, primarily calcium and magnesium ions. These minerals can accumulate in pipes and appliances, causing scaling and reducing their lifespan.

  • Calcium: High levels of calcium in water can contribute to the formation of scale and deposits in pipes and appliances. This can reduce the efficiency of water heaters, increase energy costs, and cause problems with plumbing fixtures.
  • Magnesium: An essential mineral for human health and is important for bone and teeth health, nerve and muscle function, and regulating heart rhythm. However, high levels of magnesium in water can cause a laxative effect.

Note that if your water has a greyish coloration or you have scale buildup on your appliances and fixtures, you may also have high levels of barium.

Emerging Contaminants

Emerging contaminants are pollutants that are newly discovered or have become a concern due to increased detection methods. Two types of emerging contaminants that have gained attention in recent years are Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) and Pharmaceuticals and Personal Care Products (PPCPs).

  • Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS): A group of synthetic chemicals that have been used in a wide range of industrial and commercial applications, including firefighting foams, non-stick cookware, and stain-resistant textiles. Polyfluoroalkyl substances are persistent and do not break down easily in the environment. They can accumulate in the human body and have been linked to adverse health effects, such as cancer, thyroid disease, and developmental issues.
  • Pharmaceuticals and personal care products (PPCPs): Chemicals found in everyday products such as prescription and over-the-counter medications, contraceptives, soaps, lotions, and cosmetics. These chemicals are designed to have an effect on the human body, and as a result, can be harmful to aquatic life and ecosystems when they enter water sources.

Primary Sources Of Drinking Water Contaminants

In this section, we will explore various sources that contribute to the contamination of drinking water or tap water. These sources can be broadly categorized into four main groups: natural sources, human activities, industrial processes, and agriculture.

Natural Causes

Your drinking water can be affected by natural sources, including elements, compounds, and organisms in the environment. 

  • Natural disasters: Natural disasters such as floods, hurricanes, and earthquakes can lead to the contamination of water sources. Floodwaters can carry pollutants from agricultural and industrial areas and raw sewage into water sources.
  • Geogenic contamination: Geogenic contamination is the contamination of water sources by naturally occurring minerals and chemicals in the soil and rocks. Examples include fluoride, which can cause dental fluorosis, and high levels of iron, which can affect the taste and appearance of water.
  • Volcanic activity: Volcanic activity can lead to the release of harmful gases and chemicals that can contaminate water sources. For example, volcanic eruptions can release sulfur dioxide, which can react with water to form sulfuric acid, leading to acid rain and acidification of water sources.

To reduce the risk of consuming harmful substances, always be cautious when drinking tap water from untreated sources.

Human Activities

Various human activities can also negatively affect the quality of your drinking water. These activities include improper disposal of household chemicals and liquid waste which may seep into underground aquifers or contaminate surface water. It is essential to dispose of household chemicals responsibly and ensure your waste management practices are environmentally friendly.

Industrial Processes

Contaminants in drinking water or tap water may also stem from industrial processes. These industrial sources of water contamination can have significant impacts on human health, aquatic life, and the environment and require careful monitoring and management to prevent contamination. Here are some examples of industrial sources of water contamination:

  • Chemical manufacturing: Chemical manufacturing plants can release pollutants such as heavy metals, solvents, and acids into water sources.
  • Petroleum and oil refineries: Petroleum and oil refineries can release crude oil, gasoline, and other hydrocarbons into water sources through accidental spills or leaks.
  • Mining and ore processing: Mining and ore processing can release heavy metals, acids, and other contaminants into water sources through acid mine drainage or tailings pond leaks.
  • Food processing: Food processing facilities can release organic matter and essential nutrients into water sources, leading to harmful algal blooms and low oxygen levels.
  • Textile manufacturing: Textile manufacturing can release dyes, detergents, and other chemicals into water sources, harming aquatic life and affecting water quality.
  • Power generation: Power plants can release heated water and pollutants such as mercury and sulfur dioxide into water sources through cooling water discharges and coal ash disposal.


Agricultural practices often involve using fertilizers and pesticides like glyphosate and atrazine, which can be carried into lakes, streams, and aquifers through rainfall runoff, snowmelt, or percolation. Moreover, concentrated animal feeding operations can introduce contaminants like nitrates, which can harm human health. Keep track of agricultural activities around your water sources to better understand potential issues.

Health Effects of Water Contaminants

Drinking water contaminants can have various health effects on you, ranging from mild to severe, depending on the type and concentration of contaminants. 

  • Gastrointestinal illnesses: Diarrhea, vomiting, stomach cramps, and other gastrointestinal symptoms can be caused by exposure to bacteria, viruses, and parasites in contaminated water.
  • Dehydration: Severe diarrhea and vomiting can lead to dehydration, which can be life-threatening if not treated promptly.
  • Neurological and developmental problems: Exposure to lead, mercury, and other chemicals in contaminated water can cause neurological and developmental issues, including cognitive impairment and learning disabilities.
  • Kidney damage: Exposure to certain chemicals and toxins in contaminated water can cause kidney damage and increase the risk of kidney disease.
  • Cancer: Exposure to certain chemicals and radionuclides in contaminated water can increase cancer risk, including bladder cancer, kidney cancer, and leukemia.
  • Dental fluorosis: High fluoride levels in tap water can cause dental fluorosis, which affects the development of tooth enamel and can lead to discoloration and mottling of the teeth.
  • Methemoglobinemia: High levels of nitrates in drinking water can cause methemoglobinemia, also known as “blue baby syndrome,” which can be fatal for infants.
  • Respiratory problems: Exposure to algal toxins in contaminated water can cause respiratory problems, including coughing, wheezing, and shortness of breath.

These health conditions can be serious and may require medical attention. It is essential to take steps to prevent exposure to water contaminants and seek medical attention if you suspect you have been exposed.

Acute Effects Of Drinking Water Contaminants

Acute effects typically occur when you are exposed to high doses of contaminants over a short period. Examples of acute impacts include:

  • Skin discoloration caused by exposure to some chemicals
  • Nausea and other gastrointestinal issues from ingesting harmful microorganisms
  • Organ damage and nervous system issues due to exposure to high levels of contaminants like arsenic

Chronic Effects Of Drinking Water Contaminants

Chronic effects typically result from exposure to lower doses of contaminants over a long time. Some chronic effects include:

  • Cancer from exposure to carcinogens like arsenic
  • Reproductive and developmental issues from exposure to contaminants like lead
  • Increased risk of organ damage and other long-term health problems due to continuous exposure to low levels of chemicals

Who Is Vulnerable To Drinking Water Contaminants?

Some populations are more susceptible to the health effects of drinking water contaminants. These vulnerable populations include:

  • Infants and young children
  • Pregnant women
  • Older adults
  • People with weakened immune systems, such as those living with HIV, undergoing chemotherapy, or taking transplant medications

Understanding the health effects of contaminants and the populations most at risk can help you make informed decisions to protect your health and the health of those around you from potentially harmful contaminants in your tap water.

Water Treatment and Filtration Methods

Effective water treatment and filtration methods are crucial when protecting yourself and your family from drinking water contaminants. In this section, you will learn the various approaches to removing harmful substances from your water supply.

Municipal Water Treatments

Municipal water supply systems employ several treatment steps to ensure the water is safe for consumption. The process often involves coagulation, flocculation, sedimentation, filtration, and disinfection. These methods work together to eliminate contaminants, such as suspended particles, bacteria, viruses, and chemical pollutants.

For example, coagulation and flocculation cause small particles to clump together and form larger particles, making it easier to remove them during sedimentation. Filtration then strains out these particles, while disinfection kills any remaining pathogens. 

It’s essential to recognize that these treatments are highly effective but not foolproof, so additional protection methods may sometimes be required.

Point-of-Use Filters

In addition to municipal water treatments, you can safeguard your drinking water with point-of-use filters. These filters, often installed at the tap or under the sink, remove contaminants as water passes through them. Some common types of filters include:

  • Activated carbon filters: Effective at removing sediments, chlorine, and volatile organic compounds.
  • Reverse osmosis systems: Efficient at eliminating dissolved salts, metals, and other pollutants. These systems can help reduce contaminants like sodium, chloride, copper, chromium, lead, arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.
  • UV filters: Efficient in destroying bacteria and viruses but does not remove chemical contaminants.

When choosing a point-of-use filter, always consider the contaminants in your local water supply and select a filter to target those specific pollutants. Regularly maintain and replace filters per the manufacturer’s instructions to ensure optimal performance.

Emerging Technologies

As water contamination concerns grow, new technologies are being developed to help combat the issue. Some emerging treatments include:

  • Anion exchange: Effective at removing negatively charged contaminants, such as arsenic, chromium-6, cyanide, nitrate, perchlorate, sulfate, and uranium. The US EPA states that the treatment capacity varies depending on the resin used and the influent water’s characteristics.
  • Nanofiltration and ultrafiltration: These advanced membrane filtration technologies can provide additional treatment barriers for water sources containing specific contaminants or when enhanced filtration is needed.

So stay informed about the advancements in tap water treatment technologies and consider adopting those relevant to your needs to ensure your water supply remains safe and clean.

Get Your Water Tested

The only way to know for sure if you have any of these contaminants in your water is to test for them. Yes, you can check your water utility’s Consumer Confidence Report, but that doesn’t analyze your home’s water. There is a lot that can change between the treatment facility and your home’s tap, in addition to seasonal changes in water additives.

Of course, if you have a private well, you are your own utility. Testing your well water once per year is highly recommended.

Certified Laboratory Test

Using a certified laboratory to test your water will provide the most robust and accurate results.

I recommend using the Freshnss Labs test kit for either city or well water. Simply collect a water sample in the provided vial, and send it back to the lab. Within 3 business days, you will receive a detailed report with all detected contaminants, any health alerts, and the best treatment options based on your testing data.

DIY Test Kits

Home test kits are a quick and cost-effective option. The downside is they are not very accurate. They are best used to spot-check for certain contaminants like chlorine or bacteria in between professional lab tests. Then if the DIY kit tests positive, you can proceed to a lab test to get the exact concentrations.

Which Filtration Method Is Most Effective At Removing Water Contaminants?

There are several types of water filtering systems available on the market that can effectively remove contaminants from water. Here are some of the most effective ones:

  • Reverse Osmosis (RO) System
    • Reverse osmosis is one of the most effective methods for removing contaminants from water
    • Uses a semipermeable membrane to remove contaminants
    • Removes dissolved solids, heavy metals, and bacteria
    • Typically includes pre-filters and carbon filters to remove sediment and chemicals
  • Activated Carbon Filter
    • Uses activated carbon to trap contaminants as water passes through the filter
    • Effective at removing chlorine, VOCs, and other chemicals from water
    • Often used in conjunction with other filtration methods
  • Ultraviolet (UV) Water Purification System
    • Uses UV light to kill bacteria, viruses, and other microorganisms in water
    • UV light disrupts the DNA of microorganisms, rendering them harmless
    • Often used in conjunction with other filtration methods
  • Distillation System
    • The distillation process boils water and captures the steam to remove up to 99.9% of impurities
    • Effective at removing dissolved solids, heavy metals, and other contaminants
    • Requires electricity and can be slow and energy-intensive
  • Ceramic Filter
    • Uses a porous ceramic material to trap contaminants as water passes through the filter
    • Effective at removing bacteria, sediment, and other particulates
    • It may not be as effective at removing chemicals and contaminants as other methods.
  • Ion Exchange Resin Filter
    • Uses ion exchange resin beads to remove dissolved minerals and heavy metals from water
    • It can be effective at removing lead, copper, and other metals
    • It may not be as effective at eliminating different types of contaminants.
  • Multi-stage Filtration System
    • Uses multiple stages of filtration, including pre-filters, carbon filters, and other methods
    • It can be effective at removing a wide range of contaminants
    • Requires more space and maintenance than other systems

Regulations and Guidelines

In this section, we will discuss some critical regulations and guidelines that have been put in place to ensure the safe provision and consumption of drinking water. These include the Safe Drinking Water Act, rules set by the Environmental Protection Agency (EPA), and World Health Organization (WHO) guidelines.

Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) was established in 1974 to protect public health by regulating the nation’s public drinking water supplies. This federal law, enforced by the EPA, sets standards for the quality of your drinking water and oversees the states, localities, and water suppliers who implement those standards. 

It sets legal limits on over 90 contaminants in drinking water, reflecting levels that protect human health and can be achieved by water systems using the best available technology. Your water supplier must comply with these standards, ensuring your water quality is within the limits set by the EPA.

Environmental Protection Agency

The United States Environmental Protection Agency (EPA) is responsible for setting and enforcing standards related to drinking water contaminants. These standards are divided into two categories:

  • National Primary Drinking Water Regulations. These are enforceable standards that set maximum contaminant levels to protect human health.
  • National Secondary Drinking Water Regulations. These are non-enforceable guidelines regulating contaminants that may cause cosmetic or aesthetic effects in drinking water, such as taste, odor, or color. According to the EPA, these secondary standards are not mandatory but serve as recommendations for water systems.

World Health Organization

The World Health Organization (WHO) provides guidance on drinking water quality by establishing international guidelines for specific contaminants. They are designed to protect public health and provide a basis for countries to set national standards. 

The WHO Guidelines for Drinking-water Quality serve as a reference for countries to develop and implement their own water quality regulations, considering their specific circumstances, such as climate, infrastructure, and culture.

By understanding and adhering to these regulations and guidelines, you can be confident in the safety of the drinking water from your public drinking water system.

Frequently Asked Questions

Can boiling water remove contaminants?

Boiling water can be an effective way to kill bacteria and viruses that may be present in your water supply. However, boiling will not remove other contaminants such as pesticides and heavy metals. In fact, boiling water can increase the concentration of contamination in some cases.

Can I test my water for contaminants?

You can test your water for contaminants either through a professional water testing service or at-home test kits. Professional water testing and health research can be more comprehensive and provide more accurate results, but at-home test kits can be convenient and affordable.

What can I do if my water supply has high levels of contaminants?

If your water supply has high levels of contaminants, it’s crucial to take action to protect your health. You may need to install a water treatment system, switch to bottled water, or take other measures to reduce exposure to harmful contaminants. It’s best to consult with a water treatment professional or your local health department for guidance on the best course of action.

      Enable registration in settings - general