Sodium content in our water

The human body is largely composed of water and contains a variety of electrolytes, including sodium. A complex system keeps the fluids in balance and thus ensures the proper functioning of all cells. If this mechanism is disturbed, life-threatening complaints can arise. But if you recognise the alarm signs correctly, you can take action against them. Find out more about the sodium content in our water below.

Sodium, together with other minerals, regulates blood pressure, water balance and acid-base balance. Its tasks also include the transmission of muscle stimuli and the transmission of nerve impulses. According to the German Nutrition Society, adults need an average of 1500 mg of sodium per day. Since our body cannot produce sodium itself, we have to supply it with food and drinks, ideally water.

For many billions of years, sodium has been transported in the form of sodium chloride (salt) through rock leaching into the sea and groundwater. The content varies depending on geological conditions. Near the coast, incoming seawater plays a role in the sodium content of groundwater and surface water. Strong winds carry sodium particles many kilometres inland. The Baltic Sea, for example, contains 0.2 to 2 percent salt, the Dead Sea as much as 28 percent. Sodium also dissolves from soils and thus enters rivers and lakes. The sodium content in our drinking water therefore depends on where it is taken from.

According to the Drinking Water Ordinance, Germany has a sodium limit of 200 mg per litre. On average, however, tap water has lower values. For more information, contact your local waterworks. If you want to determine the sodium content of your tap water yourself, you can do so with a water analysis. A water sample is taken and analysed in a laboratory. The analysis also provides information on whether the drinking water is contaminated with other pollutants such as heavy metals or pesticides. There are various filter systems that you can use at home to filter unwanted substances out of tap water. These include table water filters or reverse osmosis systems, which are installed under the sink.

Water softened with a softening system (also: decalcification system) has an increased sodium content. The system removes calcium and magnesium from the water and exchanges it for sodium ions. Especially people who are dependent on a low-sodium diet due to pre-existing conditions must take this factor into account. For every degree dH (German hardness) that is removed from the water during water softening, 8 mg of sodium per litre are added. For example, if the water hardness is to be reduced from 20° dH to 4° dH, this results in a plus of about 128 mg sodium per litre.

Natural mineral water can have both a low and a high sodium content. The bottle label provides information on this. Water labelled as "containing sodium" contains more than 200mg/l sodium. The addition "Suitable for the preparation of baby food" or "Suitable for a low-sodium diet" indicates a sodium content of less than 20mg/l. High sodium concentrations in water also change the taste. High-sodium water tastes saltier, whereas low-sodium water tastes milder.

Salt (sodium chloride) is added to many processed foods, which means that the daily intake of sodium tends to be too high. Nevertheless, a sodium deficit can occur after excessive water loss through heavy sweating, vomiting or watery diarrhoea. If there is no adequate water intake and the body is insufficiently supplied with sodium, deficiency symptoms such as weakness, fatigue, drowsiness and dry mucous membranes occur. A chronic sodium deficiency can cause symptoms such as confusion, memory problems and dizziness. This increases the risk of falls. If hyponatremia is suspected, the doctor will order a blood sample or a measurement in the urine. The normal value for sodium in the blood is 135 to 145 mmol/l, in 24-hour urine 120 to 220 mmol/l is optimal.

Our body has various mechanisms for regulating sodium levels. It excretes excess sodium through the kidneys in urine or sweat. If this is not enough, it withdraws water from the cells and creates thirst so that the person concerned drinks. This dilutes the sodium concentration in the blood and the sodium levels normalise. However, severe fluid loss, for example in the case of severe gastrointestinal diseases, can drive up sodium levels. This is because the lack of fluid causes the blood volume to decrease and the sodium content to increase in proportion. Older people in particular with an impaired perception of thirst run the risk of developing excess sodium (hypernatremia). This leads to muscle cramps and functional disorders of the brain. Those affected can even fall into a coma.

Only with a balanced sodium concentration can all bodily functions run smoothly. For healthy people, it is irrelevant whether they consume low-sodium or high-sodium water. The required amount is mainly absorbed through food. However, certain circumstances can cause a shift in sodium levels. After high water losses, we can help the body regulate by drinking sodium-rich mineral water. Those who want to reduce sodium for health reasons are better off using low-sodium water or simply drinking tap water.