Hard water is one of the most common water-quality terms people encounter after moving to a new city, and also one of the most misunderstood. Most people don't think about their water until something changes: you move somewhere new, your hair starts feeling different, or white marks appear on the shower glass and never quite disappear. That's usually the moment a term you'd never paid much attention to suddenly matters – hard water.
Hard Water Is Not Dirty Water
One of the biggest misconceptions is that hard water means poor-quality water. It doesn't. Hard water simply contains higher levels of naturally occurring minerals – primarily calcium and magnesium – that the water picks up as it moves through rock and soil. In many parts of Europe this is completely normal, and some of the cleanest drinking-water systems in the world are also hard-water systems. Hard water isn't contamination. It's chemistry.
What Makes Water Hard?
As water moves through the ground, it dissolves minerals from rock and soil. The more calcium and magnesium it picks up, the harder the water becomes. Hardness is commonly measured as milligrams per litre of calcium carbonate equivalent (mg/L CaCO₃). A simplified guide:
| Classification | Hardness |
|---|---|
| Soft | below 75 mg/L |
| Moderately hard | 75–150 mg/L |
| Hard | 150–300 mg/L |
| Very hard | above 300 mg/L |
Commonly used hardness classifications based on calcium carbonate (CaCO₃) concentration. Reference: World Health Organization, Hardness in Drinking-water (2011).
Not All Water Is the Same
The difference between cities can be substantial.
| City | Approximate Hardness |
|---|---|
| Seoul | ~61 mg/L CaCO₃ |
| Paris | ~250 mg/L CaCO₃ |
| London | 250–300 mg/L CaCO₃ |
| Berlin | ~303 mg/L CaCO₃ (17 °dH) |
Sources: Seoul Arisu Waterworks; Eau de Paris / ARS Île-de-France; Thames Water; Berliner Wasserbetriebe.
For someone moving from Seoul to Berlin, the water contains around five times more hardness minerals. It isn't just something you measure – for many people, it's something they notice in their hair, skin and shower environment.
What Hard Water Can Affect
Hard water doesn't affect everyone the same way. Some people notice very little; others notice changes almost immediately. Common experiences include:
- Hair that feels rougher or harder to manage
- Increased mineral residue on skin and hair
- Soap that feels harder to rinse away
- Limescale around taps and shower heads
- Skin that feels less comfortable after showering
These experiences vary from person to person, and water hardness is one of several variables involved.
Hard Water Is Not the Enemy
At PICKI NIKI, we don't believe every mineral needs to be removed. Hard-water minerals aren't inherently bad: calcium and magnesium occur naturally throughout the environment and are safe to drink. The challenge isn't that the water is unsafe – it's how that water interacts with skin, hair and the shower environment over repeated exposure. That's an important distinction.
Why We Don't Try To Remove Every Mineral
PICKI NIKI is not a water softener. Hard water remains hard. Instead, we focus on the variables a shower filter can realistically influence: neutralising chlorine, capturing particles, and bringing alkaline water toward a more skin-friendly pH. The vitamin C stage also interacts with hard-water minerals through a mild chelating action – not strongly enough to soften the water, but it may help reduce the residue they leave behind on skin and hair. You can read more about how that works on the Why It Works page.
Our goal was never to remove every mineral. It was to create water that works better for skin and hair, with the water people already have.
