Common Contaminants Found in Tap Water

Here at Pick Comfort, we spend a lot of time discussing filtration and how to soften your water while touching on topics like high-powered shower heads. Whether the water comes from your bathroom sink or an outside faucet, it’s important to know what’s in your H2O. Even if you don’t drink straight from the tap, your water filter may have trouble fighting back against some of the common containments found in tap water.

Water Safety Agencies 

Before we get to the top contaminants found in water supplies across the United States, you need to understand how that water gets to your home in the first place. The water in your home can actually come from many places, including water towers and reservoirs. It will vary depending on your location along with the size of your town or city. In a rural area, your water may come from a different type of facility than someone in the city.

Regardless of where your water comes from, it needs to be treated. That introduces a few chemicals into the mix that may need to be dialed down by the time it reaches your home. From the water treatment facility, the H20 will flow through a series of pipes before eventually finding its way to your home. Plenty of things can alter the water along the way as well. The pipes inside your home and the service connections outside usually have a lot to do with the end result.

Agencies like the EPA set guidelines for drinking water, but there are tiers for those contaminants. Critical contaminants have to meet strict guidelines before water is deemed safe to drink. There are other contaminants that are considered secondary, however, which can alter the taste or smell. At this time they have regulations set for over 90 contaminants and a large CCL or contaminate candidate list as well.

Common Contaminants Found in Tap Water

Common Contaminants Found in Tap Water

Whether your tap water is crystal clear or slightly cloudy, you’d be surprised by how many particles end up in your drinking water. That includes contaminants that occur naturally along with manmade issues and additives introduced into the water supply to clean things up.

Obviously, the treatment facility in your region takes care of most contaminants, and the National Primary Drinking Water Regulations plays a large part in that. They are treatment standards for public water systems in the United States, and legally enforceable. They classify things into six categories with Disinfectants, Disinfection Byproducts, Organic & Inorganic Chemicals, and Radionuclides.

With that in mind, most consumers simply want to deal with reducing excess disinfectants from their water or may have an issue with a few specific contaminants. We aren’t going to go through all of the contaminants the EPA covers or delve into their secondary list, but there are a dozen frequently found in many regions across the U.S. Others may only appear in your tap water if you live in certain areas or rely on a private well for water.

You will also need to understand a few terms when dealing with levels of contaminated water. MCL stands for Maximum Contaminant Level and represents the highest limit of a contaminant allowed in drinking water. MCLG is the Maximum Contaminant Level Goal, a number below this “goal” lets you know there is no expected risk to your health. MCL levels are enforceable while MCLG levels are not.

Tap Water Additives

Unless you live off the land and drink from a stream or have a well, the water from your tap is treated with additives. That includes disinfectants and byproducts that may not put you into the hospital but could potentially cause mild irritation to major discomfort in several different ways.

  • Chlorine - Chlorine is the most common additive used to treat water in municipal facilities, and while it works wonders against microbes, it’s not good in excess quantities. Too much chlorine in your water can irritate your eyes and nose, something most of us have experienced in swimming pools. Thankfully, it’s one of the easiest things to remove or reduce, and a simple water filter pitcher could do the trick!
  • Chloramine - Chloramine is another minor irritant that’s used in municipal water treatment. It might cause your water to taste or smell a little, but it’s another thing you can get rid of with a POE filter and some activated carbon. While similar to chlorine, chloramines are a major concern with dialysis water as hemolytic anemia could occur.
  • Fluoride – Fluoride is another additive and a chemical that’s been in the news numerous times over the years when it comes to water safety. Initially introduced as a way to combat tooth decay, mottled teeth or even skeletal fluorosis are ailments children may encounter from excess fluoride. EPA MCL levels are set at 4.0 mg/L, and while fluoride can be difficult to remove, it is easily reduced with a fluoride water filter.

Heavy Metals

Toxic heavy metals are natural and something you may encounter every day in very low concentrations. While usually not harmful, when experienced in high concentrations, exposure to heavy metals can result in sickness and eventually death. Heavy metal contamination is something to be aware of with private well water and rural areas. It can also be difficult to treat depending on the contaminant.


While what you’ll find in your water does vary from state to state, Lead is one of the most common contaminants across the globe. That’s because it was popular in plumbing lines used both indoors and out. In fact, lead is still found in older homes today along with lead paint, asbestos and other outdated building materials.

Children are especially sensitive to lead, and the action level is listed at 0.015 mg/L. Potential health concerns include slow development in children, including learning disabilities and kidney problems and high blood pressure for adults. Lead is nasty, but not difficult to reduce if you have one of the best water filters in your system.


You’re not as likely to encounter Chromium as other chemicals on our list, but there are two types with `
Chromium-3 and Chromium-6. Both are covered by the same standards from the EPA, although Chromium-6 is the more toxic of the two. Long term exposure could cause allergic dermatitis if you exceed the 0.1 mg/L limit.

Chromium is used in the manufacturing of steel and is a common ingredient in pigments as well. It can leech into the water supply from pulp or steel mills, but also comes from natural erosion like many contaminants. 


Cadmium is another inorganic chemical, and something that’s commonly listed among the contaminants reduced by household water filters. In this case, you’ll need to turn to reverse osmosis, distillation, or ion exchange more often than not, but it depends on the levels and style of filter.

The levels for Cadmium are set at 0.005 mg/L, and for a good reason, as it can cause severe issues like diarrhea, cramps, and nausea, among other maladies. With continued exposure to water with Cadmium over acceptable limits, you could experience kidney or liver damage. Cadmium occurs naturally through erosion, but can also come from corroded galvanized pipe, factories and runoff waste from paint or batteries.


Arsenic is one of the few chemical elements most homeowners we are familiar due to its deadly nature in film and TV over the years. If you live in the western half of the U.S., there’s a greater chance to find arsenic in your water, but it can find its way into your H2O through erosion, runoff and as a byproduct of industrial waste.

Issues caused by Arsenic include an increased risk of cancer, skin damage, or problems with your circulatory system. 100mg can lead to severe poisoning, but the allowable limit for water is 0.010 mg/L with a goal of 0 mg/L. Some multi-stage filter pitchers can bring Arsenic down to more manageable levels, but a reverse osmosis system is better suited to the task.


Mercury may be the planet closest to our sun, but it’s also an element you may find in tap water. You’ve seen metallic mercury used in thermometers, but methyl mercury is organic and can end up in the water table. Mercury also comes from erosion, factories, and through runoff from farmland.

Kidney damage is the most common side effect from prolonged exposure to Mercury through a water source. The limit is 0.002 mg/L for MCLG and MCL. RO, coagulation/filtration, and GAC are all approved methods to reduce Mercury according to the EPA.

Microscopic Menaces 

Under the microorganism category, you’ll find all kind of nasty contaminants including bacteria and viruses, and parasites. There are no “acceptable” levels for these organic and microbial contaminants as you simply do not want them in your water under any circumstances. It’s another problem you are more likely to encounter with well water, and some of these mighty microbes will require a UV filter or reverse osmosis.

  • Coliforms – Coliforms in water is something more people have become concerned about in recent years. It’s a bacteria used as an “indicator” which lets you know if a more serious problem could be present in your water. That would be fecal contamination or E.coli, a sub-group of coliform, and something that will definitely make you ill. If you use well water or want to learn more about coliforms, give this a read.
  • Legionella - While not as recognizable as E.coli from a media standpoint, Legionella is another form of bacteria, but one that can appear naturally in aquatic or damp environments. That includes premise plumbing, and it can grow in cooling towers and hot tubs as well. Legionellosis, Pontiac Fever and Legionnaires’ disease are just a few issues brought on by Legionella. 
  • Cryptosporidium & Giardia – These two containments are waterborne pathogens that cause things like cramping, diarrhea, and general gastrointestinal distress. Both are protozoan parasites and use protective cysts which keep them active, which can also make them difficult to kill. They mainly come from contaminated feces and overflowing waste but can be reduced through reverse osmosis and other water filtration methods.

Chemicals, Radionuclides and Other Contaminants (summarize and bold, no bullets)

As mentioned, if you live in the city or county, your water is generally pretty clean in the United States. There are always exceptions and disasters that can send toxic sludge into rivers, but water treatment plants to a good job. In some cases, too good of a job if your water is over-chlorinated.

Copper is common in the plumbing world, and you can end up with copper in your lines through corrosion although it’s not the only reason you’ll find it in your water. Too much copper in your water can bring on stomach cramps, vomiting, muscle pain, kidney failure, or liver poisoning. Copper can be harder to get rid of than other metals as well, so a reverse osmosis system is usually your best option unless you opt for a specialized filter.

While not quite as fearsome as Arsenic, long term exposure to Barium can lead to higher blood pressure. In the short term, you can still experience weakness or gastrointestinal distress from barium in your water and the MCL/MCLG levels for Barium are set to 2.0 mg/L, but can be reduced or removed through several methods including distillation, filtration and reverse osmosis.

Chemicals often leech into the water just like heavy metals. Fertilizers can be a major concern, and runoff could raise the Nitrate and Nitrite levels in your water. Natural mineral deposits and a leaky septic system can have the same effect. These contaminants are extremely hazardous to infants under six months of age. If you live in areas with farmland, chemicals may be a concern, and the same goes for the land around factories.

Benzene is used in everything from nylon to rubber but is also a common solvent that ends up in the water table. Natural contaminants like Manganese fall under the EPA’s secondary standards but can change the color or your water, stain your cups, and give water a metallic taste. Aluminum, Sulfate, Silver, and Zinc are other secondary contaminants that can directly alter the aesthetics of the water in your home.

Final Thoughts

It’s great to have limits to use as a guideline if you are concerned about the quality of water in your home, but it’s important to remember that Mother Nature or a mishap at a treatment plant can have in immediate impact on your water supply as well. If you are concerned about your water quality, get a report from the local regulatory body in your area before deciding which contaminants you may need to remove or reduce.