Unlike mineral water, tap water is not a natural product. In Germany it consists of approximately 2/3 ground water and 1/3 surface water (rivers, lakes, large water dams). To comply with hygiene specifications and general quality requirements, this water must first be treated and purified before it may be labeled drinking water. Various procedures and chemical additives are permitted to this purpose.
Since tap water is used for many different purposes it must be as neutral as possible – and also because that is the only way it can be distributed through a huge network of pipes. Due to this a liter tap water contains only about 200 to 300 mg of minerals. The “neutral“ composition is maintained by adding raw treated water if necessary.
Contrary to natural mineral water, central characteristics of the treated water may be altered during drinking water treatment. The following things are permitted:
- filtration to remove solid particles and solubilized substances (organic compounds, pesticides, etc.) and to achieve microbiological stabilization (adsorption filtration)
- disinfection (chlorine, chlorine dioxide, ozone)
- deacidification (pH-value regulation)
- softening (until a certain residual hardness is achieved)
- de-ironing, demanganization, desulfurization
- coagualation nitrate reduction
- ion exchange
- addition of corrosion inhibitors (phosphates, silicates)
- treatment with additives
Here you can find further information on the following subjects: