Hard water makes hair brittle and prone to breakage.

Comparative studies between soft and hard water found that hair exposed to hard water has lower tensile strength. The mineral deposits can lead to increased stiffness, making the hair more susceptible to mechanical breakage (Srinivasan et al., 2013).

Fokus Haar: Struktur, Farbe und Glanz

Hartes Wasser macht Haare spröde und brüchig

In Vergleichsstudien zwischen weichem und hartem Wasser wurde festgestellt, dass Haare, die hartem Wasser ausgesetzt waren, eine geringere Zugfestigkeit aufweisen. Die Mineralablagerungen können zu einer erhöhten Steifigkeit führen, was das Haar anfälliger für mechanischen Bruch macht (Srinivasan et al., 2013).

Chlor kann die Pigmentierung gefärbter Haare angreifen

Chlor, das oft zur Desinfektion eingesetzt wird, wirkt als Oxidationsmittel. Es kann die Pigmentierung von coloriertem Haar angreifen und zu unerwünschten Farbveränderungen (z. B. einem Grünstich bei hellem Haar durch Kupferionen) führen (Evans et al., 2021).

Gesunde Kopfhaut und Talgregulation

Die Ansammlung von Mineralien (Build-up) kann die Poren der Kopfhaut verstopfen und zu Juckreiz oder Schuppenbildung beitragen, da die natürliche Talgregulation gestört wird (Gomes et al., 2017).

Focus on skin: Barrier function and irritation potential

Interaction with surfactants (cleaning agents)

Hard water contains high concentrations of calcium and magnesium ions. These react with soaps and surfactants to form so-called "lime soaps." These residues are more difficult to rinse off and can irritate the skin's surface (Arkwright et al., 2020).

Influence on pH value

Studies show that washing with hard water can temporarily raise the pH level of the skin surface. A disrupted pH balance is associated with a weakened skin barrier and increased dryness (Danby et al., 2018).

Prevention in cases of atopic predisposition

There is evidence that early exposure to hard water may increase the risk of developing atopic eczema in infants. Therefore, reducing calcium levels is being discussed as a preventive approach (Perkin et al., 2016).

Filtration of chlorine and heavy metals

Chlorine byproducts

When showering, warm water produces chlorine vapors. Inhaling trihalomethanes can irritate the respiratory tract of sensitive individuals. Activated carbon filters are able to significantly reduce these volatile organic compounds (VOCs) (Xu and Weisel, 2003).

Heavy metals from pipelines

In older buildings, lead or copper can leach from the plumbing into the shower water. KDF filter media use electrochemical oxidation/reduction to bind these metals within the filter medium, thus reducing exposure to skin and hair (Kim et al., 2015).

Myths

"Filters heal skin diseases such as neurodermatitis."

Incorrect. Shower filters are not medical devices. However, they can reduce irritating factors (chlorine, limescale), which supports basic hygiene and can alleviate symptoms. A cure is neither legally nor medically guaranteed.

"Filters remove 100% of all bacteria."

Conditional. While some filter media inhibit bacterial growth (have a bacteriostatic effect), they do not replace sterile treatment. In Germany, however, tap water is already very safe from a microbiological perspective.

"The filter lasts forever"

Incorrect. Filter media are consumables. Once the binding capacity (e.g., of activated carbon) is exhausted, its effectiveness diminishes. Regular replacement (usually every 6 months) is essential for hygiene and effectiveness.

Detailed list of sources