Common Drinking Water Contaminants

Common drinking water contaminants

How often do you stop and think about what your drinking water contains? While municipal tap water is, of course, processed to meet drinking water standards, that’s not to say that it doesn’t contain a whole host of contaminants that affect water quality.

This guide serves as a point of information for learning everything you need to know about drinking water contaminants in the US, what they do to water, and how you can remove them.

Types of Drinking Water Contaminants

There are four types of tap water contaminants to be aware of: physical, chemical, biological and radiological.

Here’s what you should know about each of them:


Physical contaminants, as the name suggests, alter the physical appearance of water. These drinking water contaminants may cause water to take on a cloudy appearance, and you may even be able to see sediment floating on the surface of the water.

They are larger than other water contaminants, and may be present in the form of sand, dust, dirt or other organic material.


Chemical contaminants can be man-made or natural. The most common chemical contaminant found in water is chlorine or chloramines, which is added to water during treatment to disinfect it.

Chemicals like pesticides and herbicides can also make their way into water by surface run-off, and may not be adequately removed during treatment.


Any microorganism found in water is known as a biological tap water contaminant.

Bacteria, viruses, parasites and protozoan can all survive in water even after it has been treated, or may make their way into water while it travels through the pipes to your home.

Biological contaminants are particularly common in private well water sources.


While radiological contaminants are the least commonly found in water, they still do exist in small amounts. The likes of uranium, cesium and plutonium may be present in drinking water across the country. Long-term exposure to these contaminants is considered a risk.

What Contaminants Are In Tap Water?

According to the WQA, there are an estimated 80+ contaminants in US drinking water at any time, all of which may pose a risk to human health.

The most common contaminants that are found in tap water are as follows:

  • Aluminum
  • Ammonia
  • Arsenic
  • Chlorine
  • Chloramine
  • Copper
  • Fluoride
  • Bacteria & Viruses
  • Lead
  • Nitrates/Nitrites
  • Sediment
  • Iron/ Rust

Common drinking water contaminants overview


Aluminum, a naturally occurring metal found deep in the earth’s crust, may not be noticeable in water, though it can cause water to take on a blue-ish tinge when it’s present in high quantities.

It’s safe to drink water that contains a very small amount of aluminum – 0.2mg/L or below – and this level of the metal can also be found in bottled water. But studies have found that exposure to too much aluminium in water can be harmful to health, and may affect kidney and liver function.


Ammonia is a colorless gas that is often used in fertilizing, metal processing, and the manufacturing of plastics, rubber, paper, and explosives.

It’s also used as a cleaning agent during water processing, though it can also get into water from surface runoff or from excretion of fish that have consumed plastics containing ammonia.

The small amount of ammonia in drinking water is considered safe, but consumption of excessive amounts of ammonia can cause issues with the nervous system, lungs, and kidneys.


As a naturally occurring chemical element, arsenic dissolves in groundwater, and is found in well water (in larger quantities) and in treated drinking water (in smaller quantities).

Certain parts of the US, including Michigan, have higher levels of arsenic in groundwater. Long-term exposure to the arsenic found in groundwater can cause cancer, high blood pressure, heart disease, and neurological issues.


Chlorine is one of the most common – and most complained-about – contaminants found in drinking water.

As the chemical used to disinfect water and make it safe for drinking, chlorine can eliminate algae and slime, but gives water a distinctive taste and smell that many people don’t like.

Chlorine is safe to drink at up to approximately 4 mg per liter, but any more than this may result in harmful health effects or cause exacerbated allergy symptoms.


An alternative disinfectant chemical is chloramine, a combination of chlorine and ammonia, which is also used during water treatment to protect against pathogens that cause waterborne illnesses.

Again, chloramine can affect water taste and smell, though it doesn’t remain in water for as long. Like chlorine, it’s safe in levels up to 4 mg per liter.


We need copper to stay healthy, and the compound can actually be found in a wide range of foods, including nuts and seeds, leafy greens, dark chocolate, and some meats. But in large quantities, copper can cause a number of health issues ranging from vomiting and stomach cramps to liver and kidney problems.

Copper normally gets into drinking water that travels through old corroded pipes, so it’s more of a problem for areas that haven’t replaced their water supply pipes in a long time.


There’s been quite a bit of debate about whether fluoride in drinking water is safe, with some people citing its health benefits, and others insisting that it’s harmful to health.

Fluoride is added into drinking water during treatment, at a maximum level of 0.7 mg per liter. While it has some dental benefits (it can prevent tooth decay and cavities), a number of studies have linked fluoride to illness and disease, including cancer and skeletal fluorosis.

Read More: The Best Fluoride Water Filter Reviews of 2021

Bacteria & Viruses

Bacteria and viruses accumulate in sewers and septic systems, and can get into water from these sources.

When water is treated, it is thoroughly cleaned and disinfected to remove these pathogens – but the same can’t be said for natural well water.

If you take drinking water from your own well source, it’s essential that you filter out potential bacteria and viruses, including e-coli, legionella and coliforms, to make it safe for consumption.


Lead usually enters water through corroded plumbing pipes, especially if the water has a high acidity. Many old homes have lead faucets, pipes and fixtures that can contribute to higher levels of lead in drinking water.

The maximum level of lead that should be in water is 0, as it’s a toxic metal that can cause harm to health even in small quantities. Consumption of lead in water can lead to high blood pressure and kidney damage, amongst other issues.


Nitrates and nitrites are particularly common groundwater contaminants, especially in rural areas. When water is processed, its nitrates level is regulated, as consumption of too many nitrates can lead to a dangerous blood disorder called methemoglobinemia. You should find no more than 10 mg of nitrates per liter of drinking water.


The most common types of sediment in water are sand, dust, rust, rocks, minerals, and other organic particles from plants and natural matter.

Sediment can sometimes appear as cloudiness in the water, and is known in this case as suspended solids.

You are far more likely to find sediment in well water, though small amounts of sediment can also be found in municipal drinking water.

Iron/ Rust

It’s hard to know when you have iron in your water, because it doesn’t show up as a color. However, when iron is exposed to air, it can leave reddish deposits, or rust, on fixtures, which can be quite a challenge to remove. Iron is generally safe in drinking water, but it can give water an undesirable taste or odor.

How to Remove Contaminants From Water

There are a number of different methods that can be adopted for removing contaminants from drinking water. These include:

Reverse osmosis filters

Reverse osmosis water filters are considered the most effective at removing the broadest range of contaminants. When compared to other methods of filtration, reverse osmosis units provide a much more thoroughly-filtered result, removing up to 99.9% of TDS from water.

Whole house water filters

Whole house water filters are generally installed at the water’s point of entry in a home, and use multiple stages of water filtration (usually 3 or 4) to remove a range of contaminants from a home’s water supply. These filters may include a pre-sediment filter, one or several activated carbon filters, and a post filter.

Under sink water filters

Under sink water filters work very similarly to whole home water filters, but on a much smaller scale. They are compact enough to fit underneath your kitchen sink – hence the name – and usually combine several filters to reduce contaminants in water before it reaches the kitchen sink faucet.

Countertop water filters

Countertop water filters can be placed on a kitchen countertop near to a faucet, where they connect up to the faucet and filter water that passes into their units through a flexible pipe. They are simple to install and easy to maintain, but don’t tend to be as efficient as other options.

Faucet water filters

You can attach faucet water filters straight onto the end of your kitchen sink faucet, and choose between non-filtered water from your faucet, and filtered water from your filter. These usually contain a single carbon filter (some which have multiple filtration layers) and can reduce chlorine, lead and some sediment in water.

Water pitchers

Water pitcher filters contain a filter, and when you pour water into the pitcher, the filter gradually reduces the impurities. It takes water pitcher filters up to 15 minutes to fully filter water. While this isn’t an immediate filtration solution, pitchers tend to be much lower in price than other filter options.

Filtered water bottles

Filtered water bottles offer a convenient way to get access to a small supply of filtered water while you’re out and about. They work like water pitchers, gradually filtering water over several minutes. They can filter out bacteria, viruses and chemical compounds from water.

Showerhead water filters

If you just want your hair and skin to benefit from better water, you can install a showerhead water filter. These can remove chlorine from water, which may be harmful when inhaled. They can also reduce elements like heavy metals. Some showerhead water filters soften water, preventing limescale.

Water distillers

A water distiller is a kind of water purification system. It works by turning water into steam, then condensing it, removing contaminants in the process. Distillers can remove organic compounds, dissolved solids, heavy metals, fluoride, and other impurities found in water.

Water ionizers

Water ionizers alter water’s pH by increasing its alkalinity. They use titanium or platinum metal plates to carry out electrolysis – a process divides the ions in water, leaving water with a more alkaline pH.

How to Choose the Right Filter

When choosing a water filter, there are a few things you should first consider.

The contaminants in your water

If you don’t know which contaminants are most prominent in your water, it’s worth buying a water testing kit and using it to find out the main problem points with your local area’s water supply. Some kits only test for one or two tap water contaminants, like chlorine or lead, while others test for a combination of chlorine, copper, lead, iron, and more.

Testing your water will help you to learn which contaminants are affecting your water’s taste or odor, so you can buy a filter that effectively removes this contaminant.

It’s especially important to test your water if you get it from a private well water source, which may contain contaminants that are harmful to your health.

Your budget

While everyone might prefer to buy a reverse osmosis filter, which removes up to 99.9% of contaminants, that doesn’t mean that everyone can afford to spend hundreds of dollars on one – plus replacement filters in the future.

Work out how much you can comfortably spend upfront, and how much you can spend on maintenance on a month-by-month basis. This will narrow your search down to several filters in your price range.

Your style preferences

Some people would rather not have their water filter on show. For these people, faucet and countertop water filters probably wouldn’t be ideal, while under-sink and whole-home filters would be better suited to them.

Other people may want a filter they can use only when they need it, and store out of sight otherwise. In this case, a water filter pitcher or a water bottle filter might be best.

Personal use

It’s worth thinking about your own day-to-day routine to determine which water filter will benefit you best. For example, if you want to drink filtered water all day, but you work away from home for the majority of daylight hours, will you really benefit from a static water filter at your kitchen sink? Probably not. You may fare better with a portable option, like a water bottle filter.

Household size

The majority of water filter systems are sized to produce a certain amount of filtered water before they will need replacing. A whole-home unit with a larger filter will typically produce more gallons of filtered water, and tends to work better for larger households.

Consider how much water is used in your home.If you have a large family, and your filter is used regularly, it may be more cost-effective for you to buy a whole-home system with a longer lifespan.