Sodium content when softened by ion exchange

During operation, the softening system exchanges the hardness-forming calcium and magnesium for sodium. This means that for each level of hardness softened, 8 mg of sodium is exchanged and added to the water. The limit value of the Drinking Water Ordinance must be observed here. This is 200 mg/l sodium. For water hardnesses up to 30 ° dH, this limit is usually not exceeded.

Calculation example 20 °dH: The water hardness is 20° dH and should be reduced to 4° dH. So 16 °dH is removed and 16 x 8 mg = 128 mg of sodium is added. This value is well below the limit.

Very high water hardness from around 30° dH

Calculation example 30 °dH: The water hardness is 30° dH and should be softened to 4° dH. So 26 °dH is removed and 26 x 8 mg = 208 mg of sodium is added. In addition, there is the sodium value already contained in the water, which can be taken from the supplier's water analysis. For example, if this is 20 mg/l, the total value in this calculation example would be 228 mg/l sodium. The limit value of the Drinking Water Ordinance would be exceeded.

As a remedy, the residual hardness is not regulated to 4° dH but to 10° dH. Then only 20° dH is softened and the sodium load is reduced to 160 mg/l. Adding the assumed 20 mg/l results in a total sodium content of 180 mg/l. The limit value of the Drinking Water Ordinance is adhered to.

If you have us assemble and commission the softening system, our technician will take this calculation into account and adjust the system accordingly.

Dosing systems as a supplement

To ensure that no limescale problems arise due to the residual hardness, a dosing system with appropriate hardness stabilizers can also be used. These largely prevent the formation of limescale in the water. The dosage is proportional to the quantity and is approved for drinking water. The values given here in the calculation examples must be replaced by the actual values.

If you have any questions, please contact us. We will be happy to advise you individually.