Common tap water contaminants and what you can do about them?

Common tap water contaminants and what you can do about them?

What are the most common tap water contaminants and substances? Which ones are potentially bad for your health and which ones are good? What do I really need to filter from tap water?

Our team of chemical engineers and water experts created a list of tap water contaminants and substances to help answer these questions.

How do I know if my tap water is contaminated?

In addition to lab testing which is the most accurate assessment of tap water quality here are 4 other methods that you can apply:

1. Smell of the tap water

Chlorine. Exposing to air for 15 minutes can dispel the odor.

Egg: Indicates bacterial growth. If exposed to air and the odor dissipates, then the problem may arise from the plumbing that should be cleaned.

Compost: Idem egg.

2. Taste of the water

Metal taste: excess minerals (old pipes).

Salty: it can be due to chlorine or sulfate ions, product of some industrial waste.

3. Turbidity / visible particals in the tap water

Brown, orange, red particles: rust in pipes.

Black particles: can come from hoses through which the water is transported.

White particles: or cloudiness in general, may indicate excess calcium or magnesium carbonate.

4. Color of the tap water

First let the water run for a couple of minutes (eliminates standing water in pipes).

Fill a glass and hold it up to the light. If the water shows any suspicious color (brown, cloudy or colorful) it could be contaminated from upstream or by rusty pipes.

If unsure then first contact your local water supplier and secondly get the water tested. Note that one lab test showing that the water is safe doesn't mean that it's always safe to drink. Lead, biofilm (bacteria) and other corrosion can happen at random intervals. 


Common contaminants and other substances in tap water

What are the most common contaminants in tap water? Which substances should you worry about? 

Here's the list of tap water substances including where they come from, limits and potential risks.

Chlorine (Cl)

TAPP filters remove 95% of chlorine.

Chlorine is added to tap water to kill bacteria and viruses and keep it safe for drinking. The amount of chlorine added depends on the local quality of the water, climate (temperature), maximum distance to the tap and other variables. 

A side effect of chlorine is unfortunately that the tap water may taste and smell poorly. To ensure the tap water is safe to drink the recommended free chlorine is 0.5mg/L at each household tap. The maximum allowable chlorine levels (Maximum Allowable Level = MAL) in drinking water is 4 parts per million (4ppm) and pose no known or expected health risk. This includes an adequate margin of safety. However, bi-products from chlorine such as VOCs and THMs may cause health issues long term. TAPP Filters remove 95% of chlorine and close to 100% of chlorine by-products.

Note: Sometimes Chloramine is added instead of Chlorine. TAPP is equally efficient in removing chloramine.

Chloride (Cl-)

Chloride does not need to be filtered.

Chloride is a natural mineral that helps maintain proper blood volume, blood pressure, and pH of body fluids.

However, excessive Chloride in water may cause salty taste. The Maximum Acceptable Level (MAL) is 250 mg/L. Chloride is a natural component of tap water without any negative health aspects. Chloride is part of the chlorification process of drinking water from harmful bacteria and viruses.



Nitrate (NO32-)

TAPP filters reduce 70-90% of Nitrate.

Nitrate is one of the most important compounds for plants. It is a rich source of Nitrogen, which is essential for plant growth.

Nitrate has no known harm effect on the human body unless it's extremely high amounts. However, excessive Nitrate in water can cause Methemoglobinemia, or \"blue baby\" disease (Lack of oxygen). The Maximum Accepted Level (MAL) is estimated to be 10 mg/L. Nitrate originates primarily from fertilizers, septic systems, and manure storage or spreading operations.



Sulfate (SO42-

Sulfate does not need to be filtered.

Sulfate is the result of the water passage through mineral rocks. Sulfate might help in protein synthesis.

Excessive sulfate may also contribute to scale buildup in water pipes similar to other minerals and may be associated with a bitter taste in water that can have a laxative effect on humans. The MAL is estimated to be 500 mg/L. Sulfates exist naturally in groundwater that is rich in minerals.



Bicarbonate (HCO3-)

Bicarbonate does not need to be filtered.

Bicarbonate is the result of Carbon dioxide (CO2) dissolution in water. Bicarbonate is an acid buffer; it regulates the pH of your body.

However, high concentration of Bicarbonate may pull calcium from water. The Recommended range is 30 to 400 mg/L. Bicarbonate is the principal alkaline constituent in almost all water supplies. Mineral water in particulate often contains high concentration of Bicarbonate.

Phosphate (PO43-)

TAPP filters remove 70-90% of Phosphate.

Phosphate, like nitrate, is essential for plant growth. Phosphate is a strong corrosion inhibitor.

High concentration of Phosphate has not shown any health risks for human. The MAL is estimated to be 6.7 mg/L. Public water systems (PWSs) commonly add phosphates to the drinking water to prevent the leaching of lead and copper from pipes and fixtures.



Calcium (Ca2+) & Magnesium (Mg2+)

These essential minerals should not be filtered.

Calcium and magnesium exist naturally in water. They are essential minerals for all living beings.

Calcium not only helps in bones and teeth strengthening, but also decreases heart conditions. Magnesium on the other hand, is essential for membrane function, protein construction and muscle contraction. No evidence is available to document harm to human health from hard drinking water. Perhaps only, a high magnesium content (hundreds of mg/l) coupled with a high Sulphate content may cause diarrhea. The Recommended Daily Intakes (RDI) for Calcium and Magnesium are 1000 mg and 400 mg.


Sodium (Na+) & Potassium (K+)

These essential minerals should not be filtered.

Potassium and Sodium occur naturally in all water (groundwater, rainwater, etc). They are the main responsible elements for nerve stimulus fluid levels control and blood pressure regulation. They also prevent cardiovascular disease.

Sodium and potassium exist in the earth's crust and are not considered toxic. They are common elements in the natural environment and are often found in food and drinking water. High level of Sodium may increase blood pressure and salty taste. On the other hand, Potassium intoxication by ingestion is rare, because potassium is rapidly excreted in the absence of pre-existing kidney damage. The Recommended Daily Intakes (RDI) for Sodium and Potassium are 2400 mg and 3500 mg.



Lithium (Li+)

TAPP filters reduce 70-90% of this element.



Lithium occurs naturally in drinking water. Although it exists at very low rate, Lithium is actually an antidepressant component.

Lithium can be found in continental brine water, geothermal waters, and oil-gas field brines. It has shown no harmful effects on human body. The MAL is 0.7 mg/l.



Fluoride (F-)

TAPP filters reduce up to 80% of Fluoride.

Fluoride is the result of water passage through rocks. Fluoride comes from fluorine, which is a common, natural, and abundant element. Fluoride is naturally present at low concentration in most fresh and saltwater sources, as well as in rainwater, particularly in urban areas. 

At its normal rate of 0.7-1.2 ppm, Fluoride reduces teeth cavities. Excessive exposure to fluoride has been linked to a number of health issues such as bone disease and parathyroid gland damage. The MAL is 4 mg/L for Europe and the US.



Heavy Metals (Lead, Copper, Arsenic, etc)

EcoPro filters reduce 90% of Heavy Metals.

Heavy metals such as Lead, Copper and Arsenic exist naturally in nature. The benefits of these metals are not really accentuated.

Most of the point sources of heavy metal pollutants are industrial wastewater from mining, metal processing, tanneries, pharmaceuticals, pesticides, organic chemicals, rubber and plastics, lumber and wood products. Bioaccumulation of these metals can cause serious health problems related to central nervous function, the cardiovascular and gastrointestinal (GI) systems, lungs, kidneys, liver, endocrine glands, and bones. Therefore these are often listed among the most common tap water contaminants even though they are unusual in Europe.

The maximum values of Heavy Metals should be less than a couple of ug/L. TAPP 2 is specifically tested for removal of heavy metals including lead.


Volatile Organic Compounds (VOC)

TAPP filters removes 95% of these compounds.

VOCs such as pesticides and herbicides exist mostly in agricultural water. They are responsible for the smell and/or the color of water.

Once VOCs get into your water supply, they can be ingested if your water is not adequately filtered. Every chemical is going to be different, obviously, but there are many symptoms that can be caused by these hydrocarbons. While some VOCs cause no known health effects, others are known to be highly toxic. Their effects vary and are dependent upon several factors including, most notably, length of time and level of exposure. The VOCs concentration should be less than a couple of ug/L. Common symptoms associated with exposure to VOCs include eye, nose, and throat irritation, nausea/vomiting, allergic skin irritation, dizziness, and visual disorders.



TAPP filters 95% of pharmaceuticals.

The ubiquitous use of pharmaceuticals has resulted in a relatively continuous discharge of pharmaceuticals and their metabolites into wastewater.

Pharmaceuticals may be released into water sources in the effluents from poorly controlled manufacturing or production facilities, primarily those associated with generic medicines. Current observations suggest that it is very unlikely that exposure to very low levels of pharmaceuticals in drinking-water would result in appreciable adverse risks to human health, as concentrations of pharmaceuticals detected in drinking-water are several orders of magnitude lower than the minimum therapeutic dose.



TAPP filters removes 100% of microplastics

Microplastics are the result of plastic waste in different kind of sources

When plastic waste enters waterways, it does not degrade as natural materials do. Instead, exposure to the suns rays, reaction to oxygen, and degradation from physical elements such as waves and sand cause plastic debris to break down into tiny pieces. The smallest microplastics identified in public reports is 2.6 micron. The precise effect of microplastics on human health is difficult to determine for a variety of reasons. There are many different types of plastics, as well as different chemical additives that may or may not be present. WHO claims the health risk of microplastics is low but better to be safe than sorry. TAPP 2 removes all microplastics larger than than 2-microns.


Total Suspended Solids (TSS)

TAPP filters removes 100% of TSS.

Total suspended solids (TSS) exist in all water sources. They can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage.

Total suspended solids (TSS) are particles that are larger than 2 microns found in the water column. They are rarely found in drinking water. However, high concentrations of suspended solids can cause many problems for stream health and aquatic life.


Pesticides & Herbicids

TAPP filters remove 95% or more of common pesticides.

Pesticides are substances that are meant to control pests, including weeds. The most common of these are herbicides which account for approximately 80% of all pesticide use. Most pesticides are intended to serve as plant protection products (also known as crop protection products), which in general, protect plants from weeds, fungi, or insects. Along with these benefits, pesticides also have drawbacks, such as potential toxicity to humans and other species.

Adsorption process using activated carbon is among the most effective techniques for the removal of pesticides in the treatment of drinking water.

Bacteria & Viruses

TAPP filters reduces Bacteria and Viruses but does not remove all.

Natural water represents an adequate environment for bacteria and viruses to grow.

Bacteria and viruses exist naturally in water. Generally the chlorine in tap water will kill all bacteria and viruses which is why filtering of these substances is not necessary for public water in Europe and North America. Viruses are the smallest form of microorganisms capable of causing disease, particularly those of a fecal origin infectious to humans by waterborne transmission; bacteria are typically single-celled microorganisms that can also cause health problems in humans, animals or plants, despite many form is ability to aid in water pollution control.



TAPP filters are not intended to change the pH although it might make it slightly more alkaline.

The pH of pure water is 7. In general, water with a pH lower than 7 is considered acidic, and with a pH greater than 7 is considered basic or alkaline. The normal range for pH in drinking water should be 6.5 to 8.5.


What water filter should I buy to remove tap water contaminants?

Based on this comparison with other water filters, TAPP 2 is the best alternative for clean, affordable and sustainable tap water.

Read more about reasons to buy a water filter today, what activated carbon filters from tap water and more.


How do I know that TAPP filters really remove these substances as promised?

We are happy you are questioning this. Here's an overview of the common tap water contaminants that TAPP filters remove and independent lab tests to prove it.

Comments or Questions?

Please contact us on if you have questions about any of the common tap water contaminants on the list, other contaminants or how TAPP filters work.

To understand if your water is safe to drink you need to understand what the possible contaminents in tap water are.

As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include:

  • Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
  • Inorganic contaminants, such as salts and metals, can be naturally occurring or result from urban stormwater run-off, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
  • Pesticides and herbicides may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.
  • Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, and septic systems.
  • Radioactive contaminants can be naturally-occurring or be the result of oil and gas production and mining activities.

Here’s a more detailed overview for you if you want to think about a home water filter:

General water quality indicators

These indicators are parameters used to indicate the presence of harmful contaminants. Testing for indicators can eliminate costly tests for specific contaminants. Generally, if the indicator is present, the supply may contain the contaminant as well. A home water filter could be a good solution.

Indicator Acceptable Limit Indication Notes
pH value 6.5 to 8.5 An important overall measure of water quality, pH can alter the corrosivity and solubility of contaminants. Low pH will cause pitting of pipes and fixtures or a metallic taste. This may indicate that metals are being dissolved. At high pH, the water will have a slippery feel or a soda taste. Some health professionals suggest that pH below 7.4 is more difficult for the body to convert but there is no scientific research to back this up.
Turbidity <5 NTU The clarity of the sample can indicate contamination.
Total Dissolved Solids (TDS) < 1000 mg/l TDS is primarly a measure of minerals in the tap water but can also be iron or manganese. High TDS can indicate that the water is very hard (causing limescale) or or a salty, bitter taste.

Water hardness

Hard water is often pointed out as a negative thing but there is no scientific evidence that water hardness has health effects. However, it can cause scale buildup in hot water heaters and other home equipment and reduce their effective lifetime.

Hardness in mg/l Hardness Level
0-60 soft
61-120 moderately hard
121-180 hard
Above 181* very hard

* level at which most people find hardness objectionable

The World Health Organization says that “there does not appear to be any convincing evidence that water hardness causes adverse health effects in humans”.

Langelier saturation index (LSI) which tells you if hard water is likely to cause limescale.

Common nuisance contaminants and their effects.

While these have no or little adverse health effects, they may make water unpalatable (undesired to drink) or reduce the effectiveness of soaps and detergents. Some nuisance contaminants also cause staining. Nuisance contaminants may include iron bacteria, hydrogen sulfide, and hardness.

Contaminant Acceptable Limit Effects
Chlorides 250 mg/l salty or brackish taste; corrosive; blackens and pits stainless steel
Copper (Cu) 1.3 mg/l blue-green stains on plumbing fixtures; bitter metallic taste
Iron (Fe) 0.3 mg/l metallic taste; discolored beverages; yellowish stains, stains laundry
Manganese (Mn) 0.05 mg/l or 5 ppb black stains on fixtures and laundry; bitter taste
Sulfates (SO4) 250 mg/l greasy feel, laxative effect
Iron Bacteria present orangeish to brownish slime in water

Standards, symptoms, and potential health effects of regulated contaminants

These are some common contaminants that have known health effects and should be included in the water report.

Contaminant Acceptable Limit Sources/Uses Potential Health Effects at High Concentrations
Atrazine 3 ppb or .003 ppm used as a herbicide; surface or groundwater contamination from agricultural runoff or leaching heart and liver damage
Benzene 5 ppb or .005 ppm gasoline additive; usually from accidental oil spills, industrial uses, or landfills blood disorders like aplastic anemia; immune system depression; acute exposure affects the central nervous system causing dizziness and headaches; long-term exposure increases cancer risks
Lead at tap 0.015 ppm or 15 ppb used in batteries; lead gasoline and pipe solder; may be leached from brass faucets, lead caulking, lead pipes, and lead soldered joints nervous disorders and mental impairment, especially in fetuses and infants; kidney damage; blood disorders and hypertension; low birth weights
Nitrates (NO3) 10 mg/l (nitrate-N)
45 mg/l (nitrate)
soil by-product of agricultural fertilization; human and animal waste leaching into groundwater methemoglobinemia (blue baby disease) in infants (birth to 6 months); low health threat to children and adults
Total Coliform <1 coliform/100 ml possible bacterial or viral contamination from human sewage or animal manure diarrheal diseases, constant high-level exposure can lead to cholera and hepatitis
Radon 300 pCi/l* naturally occurring gas formed from uranium decay; can seep into well water from surrounding rocks and be released in the air as it leaves the faucet breathing gas increases chances of lung cancer; may increase risk of stomach, colon, and bladder cancers

Note about lead: If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. Lead is unlikely to appear in hard to very hard water.

* Recommended level in water at which remedial action should be taken. No mandatory standards have been set.

Other substances to look for

These substances are unlikely to be above the recommended limit and thus cause any harm but could be included in the report.

Substance Acceptable Limit Sources/Uses Potential Health Effects at High Concentrations
Fluoride 1.5 mg / l traces of fluorides are present in many waters; higher concentrations are often associated with underground sources. elevated fluoride intakes can have effects on skeletal tissues; skeletal fluorosis (with adverse changes in bone structure) may be observed when drinking water contains 3–6 mg of fluoride per litre.
Chloramine 3 mg / l Chloramines (Mocnchloramine, Dichloramines, and Trichloramine) are present both in chlorinated water and potentially as a vapor above the surface of the water. No short or long-term health effects have been associated with Chloramine. The only exception is dialysis patients that should avoid chloramine entirely.
Cyanogen chloride 0.3 mg / l Cyanogen chloride may be formed as a by-product of chlorination or chlorination of water. It is also formed by the
chlorination of cyanide ions present in raw water.
On inhalation, a concentration of 2.5 mg/m3 causes irritation. Cyanogen chloride was used as a war gas in the First World War. A concentration of 120 mg/m3 was lethal.
Trihalomethanes (THM) 0.08 mg / l or 80 ppb Trihalomethanes are formed as a by-product predominantly when chlorine is used to disinfect water for drinking. The most common is Chloroform. The trihalomethanes have demonstrated carcinogenic activity in laboratory animals. (Cancer Group B)
Haloacetic acids 60 ug/l Haloacetics acids are formed as a by-product predominantly when chlorine is used to disinfect water for drinking Excessive levels can cause nervous system and liver effects.
Chloroform 0.07 mg / l or 70 ppb Part of the trihalomethanes (see above) may be listed on its own. The trihalomethanes have demonstrated carcinogenic activity in laboratory animals. (Cancer Group B)
Chlorite 1 mg / l Part of the trihalomethanes (see above) may be listed on its own. Excessive levels can cause hemolytic anemia.
Bromate 10 ug / l Part of the trihalomethanes (see above) may be listed on its own. Excessive levels cause gastrointestinal, kidney, and hearing effects.


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