Contamination in your tap water

Do you need a water purifier for healthy drinking water?

In general tap water in Europe is highly regulated and therefore safe to drink. But there are a few things you should know about those regulations and the contamination we can find in our water.

Water contaminants and quality overview

To understand if your water is safe to drink you need to understand what are the possible contaminants and how to read them, a home water filter is a good idea if you find your water is not good enough. Below is an overview of the water attributes, contaminants and possible health impact. In other pages we have articles talking about how a home water filter can solve your issues.  This is based on what the WHO, US EPA and EU regulatory bodies and scientist publicly state today. However, this may change as new studies uncover new evidence.

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, which 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, which 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.
  • Hormones like estrogen, according to studies, more than 2.5 billion women are using contraceptive pills which are flush down at the toilets and into the water supply. There are studies that show the water to be positive in pharmaceuticals. These include ACE inhibitors, antidepressants, antibiotics, beta-blockers, carbamazepine, fibrates, painkillers, and tranquilizers.
  • Radioactive contaminants, which can be naturally-occurring or be the result of oil and gas production and mining activities.

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.

IndicatorAcceptable LimitIndicationNotes
pH value6.5 to 8.5An important overall measure of water quality, pH can alter corrosively 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 NTUClarity of sample can indicate contamination. 
Total Dissolved Solids (TDS)<500 mg/lDissolved minerals like iron or manganese. High TDS also can indicate hardness (scaly deposits) or cause staining, 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/lHardness Level
61-120moderately hard
Above 181*very hard

* level at which most people find hardness objectionable

The World Health Organisation 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 sulphide, and hardness.

ContaminantAcceptable LimitEffects
Chlorides250 mg/lsalty or brackish taste; corrosive; blackens and pits stainless steel
Copper (Cu)1.3 mg/lblue-green stains on plumbing fixtures; bitter metallic taste
Iron (Fe)0.3 mg/lmetallic taste; discolored beverages; yellowish stains, stains laundry
Manganese (Mn)0.05 mg/l or 5 ppbblack stains on fixtures and laundry; bitter taste
Sulphates (SO4)250 mg/lgreasy feel, laxative effect
Iron Bacteriapresentorangish to brownish slime in water

Standards, symptoms, and potential health effects of regulated contaminants

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


ContaminantAcceptable LimitSources/UsesPotential Health Effects at High Concentrations
Atrazine3 ppb or .003 ppmused as a herbicide; surface or ground water contamination from agricultural runoff or leachingheart and liver damage
Benzene5 ppb or .005 ppmgasoline additive; usually from accidental oil spills, industrial uses, or landfillsblood disorders like aplasticaremia; immune system depression; acute exposure affects central nervous system causing dizziness, headaches; long term exposure increases cancer risks
Lead at tap0.015 ppm or 15 ppbused in batteries; lead gasolines and pipe solder; may be leached from brass faucets, lead caulking, lead pipes, and lead soldered jointsnervous disorders and mental impairment, especially in foetuses 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 fertilisation; human and animal waste leaching to groundwatermethemoglobinemaia (blue baby disease) in infants (birth to 6 months); low health threat to children and adults
Total Coliform<1 coliform/100 mlpossible bacterial or viral contamination from human sewage or animal manurediarrhoea diseases, constant high level exposure can lead to cholera and hepatitis
Radon300 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 to cause any harm but could be included in the report.


SubstanceAcceptable LimitSources/UsesPotential Health Effects at High Concentrations
Fluoride1.5 mg / ltraces 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.
Chloramine3 mg / lChloramines (Mocnchloramine, Dichloramines and Trichloramine) are present both in chlorinated water and potentially as vapour 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 chloride0.3 mg / lCyanogen chloride may be formed as a by-product of chloramination or chlorination of water. It is also formed by the
chlorination of cyanide ion 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 ppbTrihalomethanes are formed as a by-product predominantly when chlorine is used to disinfect water for drinking. Th emost common is Chloroform.The trihalomethanes have demonstrated carcinogenic activity in laboratory animals. (Cancer Group B)
Haloacetic acids60 ug/lHaloacetics acid are formed as a by-product predominantly when chlorine is used to disinfect water for drinkingExcessive levels can cause nervous system and liver effects.
Chloroform0.07 mg / l or 70 ppbPart of the trihalomethanes (see above) but may be listed on it’s own.The trihalomethanes have demonstrated carcinogenic activity in laboratory animals. (Cancer Group B)
Chlorite1 mg / lPart of the trihalomethanes (see above) but may be listed on it’s own.Excessive levels can cause hemolytic anemia.
Bromate10 ug / lPart of the trihalomethanes (see above) but may be listed on it’s own.Excessive levels causes gastrointestinal, kidney, and hearing effects.

How to protect yourself from contamination and enjoy your tap water.

There are different water filter options available on the market but only reverse osmosis systems eliminate all contamination reliably. Read more about it in our blog post here

Because of the extremely high filter performance of reverse osmosis systems you might have heard that they even filter healthy minerals out of you tap water. Only a few systems on the market make sure that these electrolytes are getting re-added to the water you drink. One of them is the Osmo from Osmosys where the filtered water can be even adjusted for different taste with a unique mineral profile. If you want to learn more about it please have a look here

How do Water Filters work?