What hardness 3-4 actually means
The Swiss hardness scale runs from 1 (very soft) to 5+ (very hard). Pre-Alpine sources like Lake Thun or Lake Lucerne deliver hardness 1-2 — soft water, hardly any visible limescale. Aargau, Solothurn and parts of the Mittelland sit at hardness 3-4: medium-hard to hard.
Concretely: 22 to 32 French hardness degrees (°fH), 250 to 350 milligrams of calcium per litre. The water comes mostly from karst springs at the southern Jura foothills — limestone rocks through which rainwater is filtered for decades, picking up calcium and magnesium.
If you don't actively manage it, the first residue appears on fittings within 6 to 12 months. After 3 to 5 years, shower heads become sluggish, silicone joints turn grey, glass surfaces grow milky — all visible, but often dismissed as 'normal'.
Where the damage
really happens.
Chrome layers on fittings lose their shine not through wear, but through mineral build-up. This layer is microporous — it traps dirt, dampens reflection, feels rough. A modern fitting looks ten years old after just two.
Silicone joints in showers, under Aargau water, become microporous and absorb limescale within just a few years — irreversibly. Once the joint turns grey, no cleaner helps. What remains is replacement by a plumber.
Glass surfaces — shower walls, mirrors — are likewise attacked. With every evaporation layer, calcium-carbonate crystals settle and, over time, etch into the glass surface. What started as a water-mark blur becomes, after 5 years, a permanent matte sheen.
Editorial · No. 2Limescale doesn't attack from above. It crystallises from within — and that's the difference.
Muharem Berisha · Owner M&MM&M · Ausgabe No. 2 — 2026
What helps.
And what damages the substance.
What really helps: after every shower, briefly squeegee the glass surfaces, and periodic (every 6 to 12 months) professional descaling with material-appropriate cleaners. The mineral layer is removed without attacking the underlying chrome or silicone structure.
What damages the substance: acidic supermarket cleaners (attack chrome layers), home remedies with pure vinegar (eat into silicone joints), steel wool or scouring milk (scratch chrome irreversibly). Anyone fighting limescale with aggression only accelerates material decay.
Once you've experienced the right method, you understand: sanitary care isn't routine — it's substance protection.
We know Aargau water.
Periodic professional descaling measurably extends the life of your sanitary fittings. We bring the right method for your material — and tell you honestly where cleaning alone is no longer enough and a plumber is needed.
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