Minerals in the Tapwater

Calcium

Calcium is a vital element for the human body and only occurs in nature as a chemically bound component of minerals, for example in limestone, marble, chalk or gypsum. As calcium compounds are water-soluble, they are washed out by the natural weathering of calcium-containing rock and thus end up in groundwater and drinking water. The Drinking Water Ordinance does not specify a limit value for calcium, as this mineral is an important building block for the formation of bones and teeth as well as for many metabolic functions. The German Nutrition Society recommends a daily calcium dose of 1000 mg for adults.

In combination with magnesium, calcium determines water hardness. Hard water forms heavy limescale deposits, which can cause serious problems in pipes. Limescale deposits narrow the passage of water pipes and scale up household appliances and boilers. Limescale also has a negative effect on the taste of the water. Soft water, on the other hand, is more suitable for cooking and for hot drinks such as tea or coffee.

Magnesium

As an alkaline earth metal, magnesium occurs in nature exclusively as a chemically bound component of numerous minerals such as carbonite, silicate and dolomite. In agriculture, magnesium is an important component of fertilizers and animal feed. Together with calcium, it is responsible for water hardness in water, although the proportion is only 15-30%.

It is essential for the human organism, especially for muscle and nerve cells, and is absorbed daily through food (e.g. in wholemeal and dairy products) and drinking water. Magnesium deficiency leads to impaired metabolic functions, which can result in nervousness, lack of concentration, tiredness, weakness and muscle cramps.

Magnesium enters groundwater and drinking water mainly through natural weathering and leaching of mineral-rich rock. One liter Tapwater contains approx. 10 mg of magnesium. There is no limit value for magnesium in the Drinking Water Ordinance. However, information on the concentration is mandatory for mineral waters.

Like calcium, magnesium causes limescale deposits and adversely affects the taste of drinking water. In the long term, it can lead to flow problems and failures due to calcification, particularly in domestic installations.

Potassium

Potassium is a common element that is contained in numerous minerals as a potassium compound. Around 95 % of the potassium used is used as potassium nitrate in fertilizer production, but also in industry. Potassium in its pure form is not soluble in water, but only as a potassium compound. The element can dissolve out of these through weathering processes and enter the groundwater.

Potassium is an essential element for the human body and is mainly found in the brain, red blood cells and muscle tissue. It controls processes such as blood pressure, the nervous system and muscle contractions. It is ingested with daily food (e.g. bananas) or through drinking water. With the help of its counterpart sodium, potassium regulates the osmotic balance in the cells and therefore also the body's fluid balance. As electrolytes, sodium and potassium are particularly important after strenuous exercise, as otherwise cramps or exhaustion can occur.

Potassium compounds are used as fertilizers in agriculture and thus also end up in groundwater and drinking water. No limit value for potassium was included in the 2017 Drinking Water Ordinance. Some potassium compounds, such as potassium chloride, potassium carbonate or potassium permanganate, are toxic, but potassium permanganate is used in water treatment to remove iron and manganese.

Sodium

Sodium is a frequently occurring, highly reactive light metal that is always found bound in nature. The best-known sodium compound is sodium chloride, our table salt. Sodium salts are almost all highly soluble in water and are found in the world's oceans, in rocks and in sedimentary layers known as brines. The average salt content of the oceans is 35 grams per liter, in the Dead Sea it is around 280 grams.

Sodium is a natural component of water and enters the groundwater from soils, rock layers and salt deposits. 100 milliliters of drinking water contain around 4 mg of sodium. Sodium is essential for the human body and, together with calcium and potassium, is one of the body's bulk elements.

Sodium influences the water balance, the acid-base balance, the electrical voltage in cells and the transmission of nerve impulses. According to the German Nutrition Society, adults should not consume more than 1.5 g per day. However, industrially processed foods and fast food mean that most people consume an unnecessary amount of salt. Excess sodium can lead to high blood pressure. Babies and small children should also drink water that is as low in sodium as possible. Mineral water is considered to be low in sodium if it has a sodium concentration of less than 200 mg/l. Tapwater is significantly lower at around 50 mg/l. Exposure to drinking water containing sodium is therefore rather unlikely.

Iron

Iron is a common metal and a main component of the earth's core. Iron tends to corrode and rust in humid environments. Biologically, it is essential for living organisms, as it is primarily responsible for the transportation of oxygen in red blood cells. The daily requirement for humans is around 10-15 mg per day. Iron deficiency has a detrimental effect on health.

Iron dissolves and thus enters groundwater and drinking water, albeit in concentrations far below critical health levels. Iron also gets into drinking water via old iron pipes or galvanized metal pipes and fittings. Homeowners of older buildings are responsible for complying with the limit values themselves. From an iron concentration of more than 0.5 mg/l, brown discoloration, deposits and a metallic taste appear in the water. However, there is only a health risk above an iron content of 200 mg/l.

Sulphate

Sulphates are salts of sulphuric acid that occur naturally as mineral compounds. Most sulphates are readily soluble in water and occur in groundwater in various concentrations. The limit value for sulphate is 250 milligrams per liter according to the Drinking Water Ordinance. An increased sulphate content in water causes damage to pipes and fittings.

Sulphate is vital for the human body, as it is involved in the formation of proteins that influence the growth and stability of cartilage, skin, hair and nails. Sulphate also aids digestion as it stimulates the flow of bile. Excessive concentrations in drinking water, on the other hand, have a laxative effect and can cause osmotic diarrhea, especially in infants. The taste of tap water becomes bitter if there is too much sulphate.