Lisa Scholl

Lisa Scholl


Sulfate in water – source, risks & prevention

Despite strict regulations by the Drinking Water Ordinance, tap water in Germany can be contaminated with pollutants. For example, drinking water may contain elevated levels of sulfate, which can affect physical health under certain circumstances. Sulfates are esters and salts of sulfuric acid. In nature, these sulfur compounds are mainly found in minerals such as calcium sulfate and magnesium. Sulfates are an important component for many metallic elements. Learn how sulfates get into drinking water in the first place, what effects sulfate has on the human body, and what dangers sulfate in water poses to plumbing in this article.

In the past, high sulfate contamination in water was caused by the so-called “acid rain” . This is generated by the combustion of fossil fuels as well as by industrial exhaust gases. This releases large amounts of sulfur into the atmosphere, where it reacts with water to form droplets containing sulfuric acid. The precipitation “acidified” the soils and thus the groundwater.

How does sulfate get into drinking water?

However, since this phenomenon hardly ever occurs in modern times, atmospheric sulfur depositions in Germany have fallen by around 90 percent. Nevertheless, the sulfate load in many regions and inland waters is very high, which is why many people have the pH value in the water determined.

Researchers at Denmark’s Aarhus University conducted a survey study and found that the sulfate in the water comes primarily from agriculture and open-pit lignite mining. In addition, the consequences of climate change are said to favor the high concentration of sulfate in the water.


Most sulfates are considered to be highly soluble in water, so they are found in various concentrations in groundwater. For example, decomposition of organic matter, weathering of minerals, and volcanism can naturally contribute to the formation of sulfate in inland waters. Nevertheless, researchers led by Dominik Zak have found that the high sulfate content is due in part to the influence of humans .

As a result of the agricultural use of sulfur-containing fertilizers, around 50 percent of the total sulfur discharged into the environment each year. According to the Danish research team, sulfate in the water is caused by fertilizer leaching from fields and fields as well as from agricultural and industrial wastewater.

The far-reaching effects of climate change, such as increased heavy rainfall, may further flush sulfate from sulfur-rich soils into waterways.

Opencast lignite mining

Coal mining areas have also been found to have unusually high levels of sulfate in the water. To mine and extract the lignite, the groundwater has to be lowered 100 meters in some cases, bringing it into contact with the sulfide minerals pyrite and marcasite in the rock. The oxidation of the pyrite in the air produces iron ochre and also sulfate. As the groundwater rises, the minerals are carried into the waterways.

For example, sulfate pollution in the Spree River has risen sharply as a result of open-pit lignite mining. In some parts, the sulfate limit for drinking water is said to be exceeded by 250 milligrams per liter.

Even the introduction of special filtering techniques or the phase-out of lignite mining does not prevent sulfate in water from being a long-term environmental problem. According to the researchers, the sulfate in the groundwater not only affects the quality of the drinking water, but also the natural material cycles of nitrogen, carbon and phosphorus.

Increased nutrient levels promote plant and algae growth in water bodies, which can cause a lack of oxygen in the water . This lack of oxygen in turn causes an increased release of phosphorus, which can also have negative effects.

Sulfates and physical health

In terms of physical health, sulfates are said to have different effects. In mineral water, great importance is sometimes even attached to a high sulfate content.

A deficiency of sulfate can lead to skin problems, brittle nails and digestive disorders. This is said to particularly affect people who suffer from chronic digestive problems anyway. For this reason, sulfates are an important part of the diet and play a major role for humans.

Important role for humans

Humans absorb primary sulfates mainly through food, but also through consumption of mineral water.

An intake in certain quantities is very important for the human body, as it cannot form sulfates itself. These are instrumental in building up the body and cartilage substance, the strength of skin, hair and nails, and the body’s own proteins. The digestion and fat metabolism of the liver and gall bladder are also said to be promoted by the intake of sulfate.

Basically, a distinction is made between the following sulfates:

  • Calcium sulfate
  • Magnesium sulfate
  • Sodium sulfate

These sulfates are said to maintain important processes and functions in the body. The vital minerals cannot be produced by the body itself, so intake through food and drinking water is necessary.

Magnesium, calcium and potassium are said to support each other in their functions and have a positive effect on health. The properties of sulfate can also be enhanced in interaction with these minerals, which should support various healing processes – especially in relation to digestion.

Sodium sulfate, for example, is often used in medicine as an aqueous solution for l axative purposes, which is said to be particularly good for cleansing the intestines or before diets and fasting cures. The solution is prepared by means of Glauber’s salts. However, in such cases, the correct concentration and dosage is crucial.

Consequences in case of overdose

Mineral water is said to contain sulfate if it contains at least 200 milligrams per liter (mg/l) of sulfate. In addition, there are so-called special “healing waters” that even have a sulfate content of at least 1,200 mg/l.

Due to the addition of important minerals, very few people in Germany suffer from a sulfate deficiency. Overdosing is also unlikely within a normal diet. However, sensitive people must definitely expect side effects if they consume a mineral water with a higher than average sulfate content.

Thus, an overdose of sodium sulfate is said to cause diarrhea and abdominal cramps. Additionally, excessive consumption of sulfate can cause nausea and bloating in some circumstances.

Water containing sulfates for babies

Babies are particularly susceptible to the symptoms of sulfate overdose. Water containing sulfates is therefore not suitable for the preparation of baby food.

As a general rule, infants should be aware of a low mineral content in the water. An infant’s kidney can only excrete small amounts of sodium, so a high intake of sulfate can cause diarrhea .

The limit value for sulfate in water that can be used for the preparation of infant food is below 240 mg/l according to § 15 of the specifications of the Mineral and Table Water Ordinance.

For this reason, not every mineral water is suitable for babies. When buying water, you should therefore always look for the words “suitable for the preparation of infant food” . In case of doubt, you should resort to special baby water.

Line pipe hazards

Sulfate in the water is also not entirely harmless for the line pipes. A high concentration of sulfate in drinking water can cause lasting damage to water pipes.

If the limit value for sulfate in the water is exceeded, this can lead to corrosion damage in the pipes. Under certain circumstances, this can cause unnoticed and insidious pipe bursts with far-reaching consequences. In addition, corrosion of the line pipes also affects the quality of the water.

Legal regulations

To avoid contamination of drinking water, the German Drinking Water Ordinance is responsible for setting the limits. The local waterworks must ensure that these values are not actually exceeded. These treat the drinking water in accordance with the legal requirements and ensure that the limit values are complied with.

However, if the limit values are exceeded, this must be reported immediately to the responsible health authority so that any necessary steps can be taken to protect consumers.

Limit values for drinking water

Since sulfate can cause digestive disorders and diarrhea in adults above 1,200 mg/l and in babies above 500 mg/l, compliance with the legal limits by the waterworks is crucial.

While other values apply to mineral water, sulfate in drinking water must not exceed a limit of 250 mg/l.

Already from a sulfate concentration of 300 mg/l, the water can take on an unpleasant taste, which clearly violates the principles of drinking water quality. The drinking water should taste pure and neutral.

In addition, the risk of corrosion of line pipes with regard to the sulfate limits also plays a major role. Corrosion of copper pipes would be particularly tragic, as this rust provides an optimal breeding ground for bacteria and other pathogens. In addition, toxic heavy metals such as cadmium, zinc, copper and lead can be released by the corrosion.

Water filter system for home

Although waterworks are required to comply with the limits set by the German Drinking Water Ordinance, they can usually filter out only a portion of the pollutants contained in drinking water.

To have better control over the sulfate in the water as well as other pollutants, special water filtration systems can be installed in the house. So-called osmosis plants are capable of filtering all harmful substances from drinking water and producing pure osmosis water.

Osmosis plant

An osmosis plant is used to produce pure and contaminant-free drinking water . This is achieved by the so-called reverse osmosis:

The raw tap water is first cleaned of coarse impurities by a filter. The water is then pressed against a semi-permeable membrane that is only permeable to water molecules. However, impurities, pollutants and any unwanted minerals remain on the other side of the membrane. These are flushed away and directed down the drain. In the next step, the osmosis water is filtered again through a post-filter and the result is drinking water free of pollutants.

For reverse osmosis, the osmosis plant uses a water line pressure from 3 bar. The higher the pressure capacity of the plant, the purer the drinking water.


The advantages of an osmosis plant are manifold. To obtain high quality drinking water, the plant filters any impurities and pollutants from the water. These include:

  • Bacteria
  • Germs
  • Viruses
  • Pesticides
  • Fungicides
  • Herbicides
  • Hormones
  • Drug residues
  • Microplastics
  • Asbestos
  • Uranium
  • Nitrate
  • Nitrite
  • Phosphorus
  • Ammonium
  • Chlorine
  • u. v. m.

Sulfates can also be filtered out of the water and subsequently added back in appropriate amounts through a water enhancement cartridge, if desired.

Although the drinking water ordinance is intended to ensure that drinking water from the pipes is not harmful to the health of the human body, there is still a risk that the waterworks do not filter out all the pollutants from the water.

In addition, not all substances are covered by the Drinking Water Ordinance, so that limit values to this effect cannot be checked by the health authorities. Thus, any chemicals with hormone-like effects can be a major burden on the body, especially if you consume tap water on a daily basis.

Accordingly, a water filtration system such as the osmosis plant ensures safety and provides the entire household with perfect and safe drinking water.

Another advantage is the versatility of osmosis water. Thus, the treated water can be used for the following things in everyday life:

  • for cooking/preparation of food
  • for ice cube making
  • for coffee, tea and other drinks
  • for lime-free use in kitchen appliances and coffee machines
  • for watering plants
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